Over the past decade, protein quality has come under intense scrutiny. Due to growing consumer focus on health and rising interest in proactive—versus reactive—nutrition, proteins have moved well beyond specialised nutrition and are now thriving in the general wellness space. In the last five years (2017-2021), the number of food and beverage global product launches with a ‘high/source of protein’ claim grew by 9%, according to Innova Market Insights. Alongside the focus on health and wellness, consumers are more focused on sustainability, driving the growth of plant-based protein food and beverage. In the past five years, the number of launches of plant protein food and beverages has grown by 17%.

With the pool of protein sources diversifying, parameters such as protein source and protein quality are becoming more important for consumers in their daily product choices. Therefore, there is an opportunity for food and beverage manufacturers to meet consumers’ needs by investing in protein quality while formulating protein food and beverage.

Protein quality differs depending on food source

Protein quality is a growing driver for consumers when purchasing protein products. With the increased popularity of plant-based food alternatives in the market, it is important to recognise that not all proteins are created equal. Certain protein sources are better suited to meet our nutritional and physiological requirements than others. There are several parameters to rank the nutritional quality of these different protein sources and consumers are becoming more familiar with them.

Protein amino acid composition

Amino acids (AAs) are the building blocks of proteins. Proteins are composed of 20 common AAs, 9 of which (Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Leucine and Lysine) are categorised as essential amino acids (EAAs) or indispensable amino acids (IAAs). Arginine and Histidine are classified as conditionally essential as they are required in populations with specific physiological needs (growth, pregnancy, disease recovery, etc.).

EAAs cannot be synthesised by the body; therefore, these must be consumed in adequate amounts in the diet to prevent nutritional deficiencies (Lopez and Mohiuddin, 2022). Some proteins naturally contain adequate levels of EAAs, this is very often the case with animal-derived sources such as egg or milk. However, many plant proteins are deficient in one or more EAAs. For example, rice is deficient in Lysine and pea in Tryptophan.

The AA profile of a protein source varies based on a number of factors, including crop variety, seasonality, protein extraction method and further processing (e.g., protein hydrolysis, heat treatment, etc.). For this reason, EAA composition can differ significantly depending on the starting ingredient, i.e., bean/grain, flour, protein concentrate or protein isolate.

Protein digestibility

Another factor that affects protein quality is digestibility. During digestion protein is broken down by the gastrointestinal enzymes into peptides and AAs. AAs are responsible for important physiological functions such as hormone or neurotransmitter production, muscle protein synthesis as well as various cellular processes (Lopez and Mohiuddin, 2022; Boye et al., 2012). The body is not capable of absorbing intact proteins (i.e. how proteins exist natively in food) and must break them down to absorb them. Therefore, protein digestibility is an important factor to take into consideration since it can directly affect the nutritional value of proteins.

In general, animal proteins are easier to digest than plant proteins. The reason for lower digestibility of plant proteins is linked to the presence of anti-nutritional factors in plants (e.g., protease inhibitors, phytic acid, tannins, lectins, etc.). These anti-nutritional factors can hinder protein digestibility and consequently reduce their bioavailability. Antinutritional factor levels may be reduced during protein extraction from plants following fractionation and heat inactivation. It has been reported that plant protein isolates, the ingredient with the highest protein purity, contain low levels of antinutritional factors (Nosworthy, 2017). For this reason, isolation of plant protein is a means to improving protein digestibility. Other processing methods can be used to improve plant protein digestibility, such as soaking, boiling, microwaving, fermentation, or hydrolysis (Boye et al., 2012).

Consumers raising awareness on protein quality

The COVID-19 pandemic has accelerated consumer’s interest in their overall health and wellness. They are actively seeking information and tools to increase their understanding of health, its link with food and beverage, as well as functional attributes and nutritional benefits that their food can provide them with. Proteins are perceived not only as a critical macronutrient, but also as a supporter of overall health, muscle health and exercise, weight management, energy and even immune health.

Kerry recently undertook a global consumer research ‘The Protein Mindset’ where it surveyed more than 6,300 consumers across 12 countries within North America, Europe, Latin America and the Asia-Pacific region to examine wellness consumer attitudes, perceptions and preferences about dairy and plant protein-fortified food and beverage.

What the research highlighted is that while taste is still the primary driver of purchase for protein-fortified food and beverage, the quality of protein is the second most important driver.

This gives a very good indicator that consumers are putting more importance on protein quality than ever before. However, protein quality is a wide subject that comprises many parameters, it is important to go further and understand what ‘protein quality’ means to consumers.

While protein quality is at the top of the list of important purchase criteria, we also notice that other protein quality specificities such as ‘source of protein used’, ‘protein type used in product’ are also highly ranked.

However, other more technical protein quality specificities such as the Protein digestibility corrected amino acid score (PDCAAS), and EAA profile are taking a comparatively lower ranking. We can clearly identify a gap as PDCAAS and EAA are not automatically linked to ‘protein quality’. We believe this represents an opportunity for brands to deliver higher quality protein along with educating consumers on the different dimensions of protein quality.

We are already noticing that technical terms such as PDCAAS or EAA are being increasingly explained and commonly used in nutrition focused social media platforms which is highlighting that protein quality is a hot topic and consumers are getting increasingly familiar with it. The research also highlighted that Asian consumers and younger generations (millennials and gen Z) are the most familiar with protein quality specificities.

On the market there have been more product launches that are communicating on protein quality by putting on back claims such as ‘complete essential amino-acid profile’, ‘high protein quality’ and ‘complete protein’ or mention of PDCAAS. This is an excellent strategy to stand out in a product offering that is getting more and more busy as protein mainstreaming keeps increasing.

Measuring protein quality

PDCAAS (Protein digestibility corrected amino acid score)

Multiple methods have been developed by the scientific community to assess the nutritional quality of proteins (for review, see Boye et al., 2012). A common nutritional score used in the food industry is the Protein Digestibility-Corrected Amino Acid Score (PDCAAS). PDCAAS has been recommended by the FAO/WHO 1991 Expert Consultation. This score takes into consideration the level of limiting EAAs in the protein as well as protein digestibility (Equation 1).

Casein is used as the reference protein. The EAA requirements for a target population of children aged 2-5 years are recommended in the FAO/WHO 1991 report.

PDCAAS varies between 0 and 1, it can also be expressed as a %, ranging between 0-100 %. In instances where a protein yields a score > 1, it is recommended that the PDCAAS should be reported as 1. Proteins having a PDCAAS of 1 are classified as nutritionally complete since they are not lacking EAAs.

Initially, PDCAAS determination involved in vivo animal studies (rat). However, in recent years, an in vitro kit based on a patented method (Plank, 2017) using Medallion’s Animal-Safe Accurate Protein (ASAP) procedure was introduced by Megazyme to determine the protein digestibility.

PDCAAS is used to calculate the % Daily value (DV) in the USA and the Protein Efficiency Ratio (PER) in Canada (Marinangeli et al., 2018). Nutritional protein claims can be made based on DV or PER of foods as follows:

‘Good source of Protein’ for DV of protein for Reference Amount Customarily Consumed (RACC) ≥ 10% or PER ≥ 20;

‘Excellent source of Protein’ for DV of protein for RACC ≥ 20% or PER ≥ 40.

DIAAS (Digestible indispensable amino acid score)

In 2013, the FAO made the new recommendation of substituting PDCAAS with the Digestible Indispensable Amino Acid Score (DIAAS). DIAAS, which was developed by the team of Prof. Moughan in the Riddet Institute (NZ), has been positioned as a superior method to quantify the nutritive value of proteins more accurately. The DIAA ratio is calculated for each IAA relative to the reference IAA and its true ileal digestibility (Equation 2). The reference AA scoring pattern (AA requirements/protein requirements for maintenance and growth) used is for children aged between 6 months to 3 years. The DIAAS corresponds to the lowest DIAA ratio.

With DIAAy ratio, the Digestible Indispensable Amino Acid ratio for AA residue y; SID, the true ileal digestibility of Indispensable AA residue y.

DIAAS assesses the ileal digestibility of proteins using animal (pig) testing. Pigs have a digestion that is similar to humans, which makes them a good model for digestibility determination. DIAAS determines the amount of EAAs actually absorbed by the body, through the small intestine instead of theoretical calculation based on residual EAAs in feces as per the PDCAAS method. In addition, DIAAS values for single foods are not truncated to 1. Therefore, DIAAS is positioned as more adequate to rank the nutritional quality of proteins. The DIAAS value can be used to categorise protein quality (FAO, 2013):

• ‘High in protein’ for DIAAS value ≥1.00;
• ‘Source of protein’ for DIAAS between 0.75-0.99;
• No protein nutritional quality claim for DIAAS <0.75

Opportunity – protein nutritional optimisation strategies

As outlined earlier, not all protein sources are able to deliver all the EAAs in sufficient amounts and differences in digestibility exist. Consumers are also getting more familiar with protein quality. Several strategies are used by the food industry to manufacture protein ingredients and foods with a complete nutritional profile. These strategies rely on knowledge of protein composition, a good understanding of how to complement different protein sources and/or enhance protein digestibility.

Plant protein combination

The most common way to optimise EAA profile in protein formulations is by combining different plant protein sources in a complimentary fashion. The plant protein combination is informed by the limiting EAA in each protein source.

In early studies, Methionine, Lysine, Tryptophan and Threonine have been identified as the most common EAAs lacking in dietary proteins (Pieniaźek et al., 1975; Chardigny et al., 2016). Most plant proteins are reported as uncomplete in terms of their ability to provide EAAs. However, there are a few exceptions, such as soy, potato and canola, which have a balanced EAA profile.

With numerous plant protein ingredients displaying uncomplete EAA profile, it is common practice to combine complementary plant proteins to improve the EAA profile in the view of increasing their DIAAS or PDCAAS value (Gorissen et al., 2018; Herreman et al., 2020). An enhanced DIAAS/PDCAAS value can be achieved by combining pulses (which are generally limited in sulfur-containing AA (Methionine/Cysteine) or Tryptophan) with cereal/grains (generally limited in Lysine). 

Food formulation with hybrid proteins

A few examples of products formulated with hybrid proteins have been available on the market for several years. However, these were not positioned as hybrid products as the main objective of combining protein sources was to achieve a cost saving. These products, which are fortified with a blend of dairy and plant protein, include mostly protein bars and nutritional beverages. There is an opportunity for food companies to better communicate on the hybrid positioning of these products and the benefits of hybrid formulations.

The rise in vegan food product launches is driven by the increasing number of consumers embracing a flexitarian diet. These consumers are eating animal-derived products, therefore, formulations combining plant and animal proteins are still consistent with the dietary choices of flexitarians. The nutritional objective of hybrid food is to allow consumers to increase their intake in plant proteins while reducing animal proteins in their diet (Alves & Tavares, 2019). Combining both animal and plant protein is an excellent strategy to improve the nutritional quality of a protein product as animal proteins are often complete and deliver all EAAs. However, there are to date only limited numbers of hybrid food launches on the marketplace.

Recent products were launched, mostly in the dairy alternative area by companies such as Premier Nutrition (Creamy Shake with oat and dairy), Live Real Farms (dairy and almond beverage), Bel (Margot brand combining milk and pulses) and Triballat (Paquerette brand blending dairy and various plant beverages).

Nutritional fortification of food products with free amino acids

AA supplementation of foods is not a novel practice. It has been employed mostly for bioactive properties of selected free AAs or AA blends (e.g., L-carnitine, Branched Chain Amino Acids – BCAAs). More recently, we are witnessing a shift whereby AA fortification of foods is used as a means to enhance their nutritional profile.

Products formulated with free AA are found in nutritional beverage applications. MyProtein has recently launched RTM beverages with complete AA profile fortified with plant proteins and Tryptophan. The company Joybraeu has launched alcohol-free beers fortified with BCAAs (with levels as high as 40-50% of the overall protein content).

Combination of intact and hydrolysed proteins

Protein hydrolysis can be leveraged to further improve protein digestibility, which may result in a better PDCAAS value. Protein hydrolysates have been used for many years in the formulation of specialised nutrition products (e.g., enteral nutrition, infant formulae, hypoallergenic products, foods for medicinal purposes, etc.). The food industry has since investigated their broader incorporation into products for the general population as they can be used as fast digestible proteins (Potier and Tomé, 2018).

Beyond dairy and plant – mycoproteins, algae, yeast, edible insects

Novel alternative proteins are emerging on the protein ingredient market. These sources originate from mycoproteins, algae, yeast and edible insects. They generally have an interesting sustainability positioning. In addition, diversification of protein sources could help alleviate the pressure on supply for conventional proteins linked to the popularity of vegan products.

Nowadays, these alternative protein options are niche since they are not manufactured at a very large scale. In addition, research on these ingredients is still in its infancy and significant work is required to better understand their nutritional profile and potential health concerns such as allergenicity and toxicity which are very much unknown.

Conclusion

With consumers integrating more plant-based protein options in their diet, protein quality is becoming an important subject matter for consumers and might become in the future a important tool of product differentiation in a crowded market. However, more education is required regarding the different parameters linked to protein quality such as EAA profile, PDCAAS and DIAAS.

This is an opportunity for protein food and beverage manufacturers to develop formulas with improved nutritional and digestibility quality while educating consumers about protein quality and how this is linked to optimal nutrition and health.

Many strategies are available to deliver better protein quality and with the increasing number of new protein sources introduced on the market the protein quality will be a key tool for consumers to choose between these different sources. Using protein quality parameters will support consumers making an informed choice for foods with good nutritional quality.

References

Alves, A. C., & Tavares, G. M. 2019. Mixing animal and plant proteins: Is this a way to improve protein techno-functionalities?. Food Hydrocolloids, 97: 105171.

Boye, J., Wijesinha-Bettoni, R., & Burlingame, B. 2012. Protein quality evaluation twenty years after the introduction of the protein digestibility corrected amino acid score method. The British journal of nutrition, 108 Suppl 2, S183–S211.

Chardigny, J.M. and Walrand, S., 2016. Plant protein for food: opportunities and bottlenecks. OCL Oilseeds and fats crops and lipids, 23(4): 1-6

FAO/WHO. 1991. Protein Quality Evaluation: Report of the Joint FAO/WHO Expert Consultation. FAO Food and Nutrition. Bethesda, Md., USA 4-8 December 1989. Paper 51. Rome: FAO.

FAO. 2013. Dietary protein quality evaluation in human nutrition. Report of an FAQ Expert Consultation. FAO food and nutrition paper, 92, 1-66.

Gorissen, S. H., Crombag, J. J., Senden, J. M., Waterval, W. A., Bierau, J., Verdijk, L. B., & van Loon, L. J. 2018. Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids, 50(12): 1685-1695.

Herreman, L., Nommensen, P., Pennings, B., & Laus, M. C. 2020. Comprehensive overview of the quality of plant‐And animal‐sourced proteins based on the digestible indispensable amino acid score. Food science & nutrition 8 (10): 5379-5391.

Lopez M.J., Mohiuddin S.S. 2022. Biochemistry, Essential Amino Acids. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557845/.

Marinangeli C.P., Mansilla W.D., Shoveller A.K. 2018. Navigating protein claim regulations in North America for foods containing plant-based proteins. Cereal Foods World, 63(5):207-16.

Nosworthy, M. G., Tulbek, M. C., & House, J. D. 2017. Does the concentration, isolation, or deflavoring of pea, lentil, and faba bean protein alter protein quality?. Cereal Foods World, 62(4): 139-142.

Pieniaźek, D., Rakowska, M., Szkiłładziowa, W., & Grabarek, Z. 1975. Estimation of available methionine and cysteine in proteins of food products by in vivo and in vitro methods. British Journal of Nutrition 34 (2): 175-190.

Plank D. W. 2017. In vitro method for estimating in vivo protein digestibility. U.S. Patent No. 9,738,920. Assignee: General Mills, Minneapolis, MN.

Potier, M. and Tomé, D., 2008. Comparison of digestibility and quality of intact proteins with their respective hydrolysates. Journal of AOAC International, 91(4), pp.1002-1006.

1. Protein Quantity – Why is more protein important for athletes?

The daily recommended allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day, which translates to 56 g for a 70 kg/178 pound man. The vast majority of people consuming a typical western style diet easily achieve this level. However, scientists have begun emphasizing that these RDAs are minimum levels set to prevent deficiency rather than levels that will optimise health based on evidence from studies.

Protein has countless functions in the human body and it is especially important for the maintenance and recovery of muscle. Muscle health is a critical determinant of athletic performance, so, for athletes, achieving optimal rather than merely adequate protein intake is key. Intense exercise causes the proteins that make up muscle to be broken down. This damage is responsible for muscle soreness and can ultimately reduce strength and function if the proteins are not replenished. Consuming protein in the diet can offset this effect. Eating a high protein meal decreases muscle breakdown and increases muscle repair and synthesis (Moore D et al., 2015). As a result, the American College of Sports Medicine advocates protein intakes higher than the RDA. Individuals who take part in endurance sports (runners, cyclists, swimmers) are advised to consume between 1.2 – 1.4 g per kg body weight per day (84-98 g per day for a 70 kg/178 pound man) while for power disciplines (strength or speed) intakes of up to 1.7g per kg body weight per day (119 g/d) are recommended.

A position paper from the International Society of Sports Nutrition came to a similar conclusion, suggesting ranges up to 2.0 grams per kg body weight for most exercising individuals depending on the type of exercise.

2. Protein Quality Matters

It’s not just the amount of protein, but also the type of protein in the diet that athletes need to take note of. Scientific research shows that simply consuming enough protein will not optimise muscle repair and synthesis because not all types of protein are equally beneficial. In order to utilise the protein we eat, the body breaks it down into basic building blocks, called amino acids. The source of the protein influences our ability to digest it properly and, therefore, the availability of these crucial building blocks. Protein from plants such as vegetables, nuts, seeds, grains, and legumes are not as well digested as protein from animal sources or soy protein.

In addition, not all proteins contain all of the amino acids the human body needs. Some amino acids, called essential amino acids, cannot be produced by the human body and must be consumed in the diet. Most plant proteins lack one or more of these essential amino acids, meaning plant sources must be combined in the diet to provide for the body’s needs. Egg, milk and soy proteins are highly digestible and contain all of the essential amino acids, meaning they are considered the highest quality proteins for humans.

Recent scientific research has allowed us to refine this list even further for athletes because when it comes to building muscle, one specific amino acid, leucine, plays a critical role (Layman D et al., 2015). Leucine acts like a molecular switch that turns on the body’s machinery for manufacturing muscle. Whey protein contains more leucine than any other source of protein and clinical studies have shown that whey stimulates muscle synthesis more effectively than other high quality proteins, especially when consumed after exercise.

This leucine trigger hypothesis has been found to be especially important for older adults, where the ability to digest and utilise protein is diminished.

3. Protein timing is of the essence

Focusing on post-exercise whey supplementation is only part of a bigger picture. Optimal muscle repair and synthesis will not be achieved simply by drinking a protein shake after a workout. Frequent training is required to improve performance. As a result, muscle breakdown, repair and synthesis becomes an ongoing process and regular intake of high quality protein is needed. We now know that consuming around 20-30g of protein can “switch on” muscle protein synthesis, but this effect plateaus when more protein is consumed (Moore D et al., 2015). This means that consuming larger amounts of protein at that same meal offers no additional benefit. For this reason, spreading protein intake throughout the day, such that 20-30g of high quality protein is consumed at breakfast, lunch and dinner, is more beneficial. This type of meal pattern will lead to more muscle synthesis and less muscle breakdown throughout the day.

A recent study carried out by researchers at Maastricht University in the Netherlands suggests that one additional snack before sleeping may further optimise muscle synthesis (Snijders T et al., 2015). Sleep is crucial, not only for athletic performance but also for general health and wellness. The hours we spend sleeping, however, constitute a period of fasting and this leaves the body vulnerable to muscle breakdown. The researchers found that consuming 20-30g of high quality protein before bed minimised muscle break down and promoted muscle synthesis during sleep, meaning that a protein packed bedtime snack could be beneficial.

Regulations for sports foods can differ between countries. Find out more details on our Regulations for Sports Foods page.

What does all of this mean in terms of diet?

Thanks to our improved understanding of the relationship between protein and exercise, we can now define not just the quantity of protein, but also the quality and timing of intake needed to optimise muscle recovery and function, and ultimately, performance.

1.Quantity: RDAs for protein are minimum rather than optimum levels. To maximize muscle health target 1.2-1.7g per kg of body weight per day

2.Quality: Protein from animal sources is easier to digest and better quality than most plant proteins. Choose high quality sources such as eggs, lean meats, milk, cheese, yogurt and soy products. If you are a vegetarian, combine plant sources of protein to ensure your body gets all of the essential amino acids.

3.Timing: It is important to consume protein regularly throughout the day. Aim to include 20-30g of high quality protein at breakfast, lunch, dinner and as a bedtime snack

Learn more – Busting Sports Nutrition Myths with Dr. Stuart Phillips and Leslie Beck, RD (podcast)

In this Eat, Move, Think podcast, protein and exercise expert Dr. Stuart Phillips from McMaster University discusses common sports nutrition questions with Leslie Beck, RD, Dietitians of Canada Chair. They answer questions like:

• Do plant-based eaters need more protein than meat eaters?
• Is chocolate milk the perfect post-workout drink?
• Which supplements actually help muscles grow?
• Do you need to consume protein within 30 to 60 minutes of strength training?

The growth of plant-based meat alternatives can be linked to health. Over the years, meat consumption’s repeated link to disease like cancer in studies and media headlines has caused many people to eat less meat.

Pea protein continues to be a popular choice of plant protein in meat alternatives. The main reason for this is their high protein content, as well as the low saturated fat and high fiber content. As the plant protein trend continues, both consumers and manufacturers look towards new and innovative sources for their food and beverage products. Among the plant-based proteins, lentil, chickpea, rice, fava, hemp and potato are rapidly growing in interest.

What affects the off-tastes of a plant protein?

• • Amount of protein in the product
  • Type of protein used
  • Extraction process: pH, temperature, processing time
  • Precipitation process: centrifugation conditions, fermentation microorganisms used, etc.
  • Drying temperature
  • Consumer storage and preparation conditions

Understanding the source of off-tastes is the first step in properly masking them. Typical plant-based protein off-tastes include: beany, bitter, cardboardy and chalky. There might also be unpleasant perceptions around aroma, mouthfeel, and astringency.

The off-tastes can be associated with varying amino acid profiles which are derived from plant-based proteins. They all have unique, inherent off-tastes along with green aftertaste depending on the plant source.

The amount of plant-based proteins used, the types of protein used, and  the protein extraction/processing/drying methods all play critical roles in generating the types of off-tastes perceived in the finished application.

Off-tastes in plant proteins differ depending on how much of the protein is in a serving of food or beverage.

Starting at the raw material, the type of protein and its serving size both dramatically contribute to off-tastes. It’s then important to take into account how the plant protein has been extracted, precipitated, and dried from the manufacturer. During extraction, the pH, temperature, processing time, and the types of treatment chemicals used can all contribute to off-notes. During precipitation, the sedimentation method, centrifuge condition (rpm, flow rate, operation time) and, if fermentation is involved, the type of microorganisms used, can all contribute to off-notes as well.

During drying, the temperature (inlet and outlet) of the spray dryer and the drying methods (freeze drying, drum drying and etc.) can contribute to off-notes.

In summary, the proprietary process that a manufacturer is using to produce the plant-based proteins will contribute its own unique off-taste. To further complicate the matter, there are a number of challenges for the developer when formulating with plant-based proteins such as different product formats, consumer’s cooking methods, storage conditions of the finished products, working with multiple suppliers with different off-note challenges, and batch to batch off-taste variation.

The principles of plant-based protein flavour masking

In order to mask multidimensional off-tastes, a multidisciplinary approach is required.

During the manufacturing process, off-flavouring molecules (e.g. specific amino acids) can be removed using physical or chemical treatments such as soaking, thermal treatment, germination, enzymatic treatment, or solvent extraction.

Another option is to mask off-taste using making agents. A major challenge is the increase in demand for natural and organic masking agents. Claims such as natural, halal, kosher, non-GMO, and organic make it difficult to use many traditional or artificial flavouring agents.

To develop clean labelled flavour masking agents, an understanding of analytical chemistry and sensory science for volatile and non-volatile compounds are required. By understanding the flavour chemistry mechanisms, one is in a better position to correlate the off-tastes to critical flavour compounds as well as to enable to the development of effective flavour masking solutions.

Off-tastes in pea protein are linked to specific chemistry. For example, in the chart above, high amounts of lipid oxidation are linked to a strong hay off-taste. Understanding what is causing off-tastes helps solve the issue at its root.

For example, prolamin coating is a known method for bitter taste masking. Prolamin is a plant storage protein which is mainly found in the seeds of cereal grains such as oat and rice and accounts for about 5-10 % of the total proteins in those plants. Manufacturers and flavour companies could produce a clean labelled flavour masking agent through extraction, separation, and purification of prolamin-rich fractionation.

Traditionally, addition of sugars, salts, and acids are used for suppressing the inherent off-taste through trial and error. However, understanding the chemistry and source of off-notes can help the masking process be more time efficient and better for health, without requiring excessive use of sugars or salts that are linked to poor health.

A study by Houston et al. (2008) showed that ageing adults who had a daily protein intake of 1.1 grams of protein per kilogram of body weight (around 88g per day for an 80kg male) lost 40% less muscle over the course of three years when compared to those who were consuming 0.8g/kg BW (around 64g per day for an 80kg male).

Let’s look at the science of plant proteins and muscle health, and how plant proteins could be optimised for active ageing.

Not all proteins are the same when it comes to healthy ageing

Plant proteins are often missing important amino acids or can be harder to digest

Most plant-based proteins are lower in certain essential amino acids than animal-based proteins and can also be harder to digest. This is reflected in the figure below, which uses a score called PDCAAS to represent the amino acid content of different proteins relative to the needs of the human body. Protein quality can also be measured using a score called DIAAS, which measures the amount of amino acids absorbed by the small intestine after protein is consumed.

What this chart shows is that consuming the same amount of whey protein compared to wheat protein will not result in the same amount of amino acids being absorbed into the body. In this example, the whey protein would provide all of the necessary amino acids for adequate muscle maintenance, whereas consuming the same amount of wheat protein would result in a lack of some of the amino acids the body needs.

When it comes to active ageing, this means plant proteins may be less efficient at activating muscle growth and repair and this must be considered when making recommendations for active ageing. For example, this article discusses the importance of leucine in activating muscle growth and repair. However, wheat protein has 37% less leucine than the same amount of whey protein (Herreman et al., 2020).

Plant proteins can be limited in their ability to stimulate muscle growth and repair in older individuals

The limited effectiveness of  plant proteins to stimulate the muscle protein synthesis system, when compared to animal-derived protein, was shown by Gorissen et al. (2016) in a study where the ability of 35g of whey, casein, or wheat protein to stimulate muscle protein synthesis was measured in 60 healthy older men (70 -72 years old).

Myofibrillar protein synthesis (FSR), during the fasting state (Basal) and over the entire (0–4 h) postprandial period after the ingestion of 35g of wheat protein (WPH-35), 35g of casein protein (MCas-35), or 35g of whey protein (Whey-35) in healthy older men (Gorissen et al., 2016).

The results from the study, shown in the figure above, show that 35g of wheat protein had little to no impact on muscle protein synthesis beyond the baseline rate (i.e., resting rate before a meal).The subjects who consumed whey or casein proteins (which are animal derived) showed an increase in muscle synthetic response. The higher response to the consumption of the animal-derived whey and casein proteins is attributable to the greater content of essential amino acids, and higher overall digestibility which is reflected directly in their protein quality values: wheat=0.48, whey=0.85 and casein=1.17, as measured by DIAAS (Herreman et al., 2020).

The participants needed to eat almost twice as much wheat protein (60g) to see the same response in muscle protein synthesis as 35g of whey or casein. This would be a difficult amount of protein to eat in one sitting, especially in older individuals where diminished appetite is common. Another consideration is the environmental impact of growing the quantity of plant protein required to maintain this increased level of consumption which could counteract some of the benefits attributed to switching from animal protein to plant protein.

How can we improve the ability of plant proteins to support muscle health during ageing?

Choose the right protein source

Plant proteins with high protein quality scores are a good place to start when it comes to active ageing. Soy protein has a DIAAS value of 0.9, which is higher than most other plant sources. Soy protein has been shown to efficiently meet the body’s need to form new muscle but some negative perceptions around soy’s role in health, many of which are unwarranted, has led some consumers to stop consuming soy protein and search for other alternatives.

Pea protein (DIAAS value of 0.71) and rice protein (DIAAS value of 0.47) have become more prevalent and application of these ingredients is increasing over recent years. Emerging plant proteins of nutritional interest also include potato (DIAAS value of 1), pseudo-cereals (such as quinoa, amaranth and buckwheat), legumes (lentils, chickpeas and lupin) and oilseeds (canola, rapeseed and hemp) due to their levels of essential amino acids (Herreman et al., 2020; Martínez-Villaluenga et al., 2020). Mostly, methionine, cysteine, lysine and leucine are four essential amino acids that cause low DIAAS values for plant proteins and, therefore, limit their nutritional quality (Lonnie et al., 2018).  Much scientific research has been conducted in this area to identify plant protein sources that are more nutritionally complete and have similar levels of these essential amino acids to that of soy and animal-derived proteins.

An alternative to finding a single source of plant protein which can act as complete source of nutrition for the healthy growth and maintenance of muscle in ageing individuals is to modify the physical, chemical or functional nature of plant proteins to optimise the effect they have on muscle growth and repair.

Improve digestibility via processing

One of the major limitations preventing plant proteins from having a high protein quality score is their limited digestibility and bioavailability. Within plants, proteins are usually encased in fibre-rich husks or layers that are very difficult for the body to digest, limiting our access to the protein when we eat it. Additionally, plants contain a range of bio-compounds, termed phytochemicals, which slow or inhibit protein digestion (Lonnie et al., 2018).

Physical processes such as cooking (i.e. heating), extrusion, drying, and enzymatic hydrolysis have all been shown to increase the digestibility of numerous plant proteins (Sá et al., 2019). For example, processing a soy flour into a soy protein isolate increases the PDCAAS score from 0.86 to 1.0. These processes can degrade the bio-compounds that limit digestibility or change the structure of the proteins to make them more accessible to the digestive enzymes in the intestine. These physical processing treatments (i.e. heating, wet fractionation, dry fractionation, drying, etc.,) are commonly used in the enrichment and isolation of plant proteins to produce protein-rich flours (e.g. protein concentrates or isolates), which results in the a large improvement in digestibility.

Blend different plant proteins together to improve amino acid profiles

Since many plant proteins are lacking in just a few essential amino acids, such as cereals being low in lysine and legumes being low in methionine, different plant protein sources can be blended to account for the other’s “amino acid weakness” so to speak. The right blend of rice and pea protein will have sufficient amounts of both lysine and methionine, creating a “complete” protein that is more efficient, gram for gram, at delivering amino acids to our muscles than either protein alone.

Plant-animal protein blends are also a possibility, since the plant-based market has expanded beyond vegans and vegetarians to flexitarians or those just looking to eat more plant-based foods. Blends of plant and animal proteins have already seen some use to enhance the functionality (e.g. solubility, taste, texture) of plant proteins in foods and beverages. A series of studies have tested the ability of milk protein, soy protein and a milk-soy protein blend to stimulate protein synthesis after exercise in both older men and young adults. Results from these studies showed that the muscle protein synthesis rates were higher and remained higher for a longer period of time for the milk-soy protein blend (Borack et al., 2016; Reidy et al., 2014, 2013), suggesting possible health benefits in consuming a plant-animal blend of protein. More research would be needed to fully understand how different protein blends interact and their potential health benefits.

Increase leucine content of plant protein

As mentioned earlier, the amino acid leucine has an important role in activating muscle growth and repair. Many plant proteins contain around 20-30% less leucine than animal proteins, although there are a few plants high in leucine, such as corn, soy, and potato (Herreman et al., 2020).  It stands to reason, then, that adding leucine to plant proteins or breeding plants to contain higher levels of leucine might improve their ability to promote active ageing.

A study by Wall et al. (2013) found that the addition of crystalline leucine (2.5g) to a 20g serving of casein had a greater effect on protein synthesis compared to the consumption of 20g of casein alone. Although this study used animal-sourced protein, it shows that addition of leucine can help overcome the reduced sensitivity of the mTOR system (responsible for initiating muscle growth and repair) that is seen during ageing. A study done in mice found that adding leucine to a wheat protein to match the leucine content typically found in whey protein led to a similar ability to stimulate muscle growth compared to whey (Norton et al., 2012).

Conclusion

To promote active ageing it is key that not only the right quantity of protein is consumed but the quality of the protein should also be considered. There are actionable strategies such as processing, protein blending, or targeting leucine content that can improve the ability of plant proteins to promote active ageing while also addressing growing concerns over the environmental impact of animal proteins.

Read Part 2 of this article: Active Ageing – How Can We Optimise Plant Proteins?

Although the average global life expectancy is now over 70 years, the focus for many people today is not “how old can I live to be?” Instead, the most important question has become “will I be able to do the things I want to do when I am older?” Retaining muscle mass is key for active ageing because it allows us to do the day-to-day activities we want to do, as well as protects us from falls and the associated injuries that can result.

Protein’s role in muscle health might be more than you think

Leucine and insulin are “switches” that activate protein synthesis

Most people think of protein, or the amino acids in protein, as the “building blocks” that our body uses to make muscle, but some amino acids have unique roles in metabolism. Scientists have shown that there is a metabolic “switch”, called mTOR, that signals new muscle production when it’s activated. Think of it as the body’s way to regulate creation or upkeep of muscle by promoting growth mainly when fuel or building blocks are plentiful (protein-rich food), or when the body senses an external need for muscle growth or repair (exercise).

Leucine, an essential amino acid that we must get through our diet, plays an important role in turning this “switch” on. When present alongside insulin, which is a hormone that has a key role in telling the body that fuel is plentiful, leucine will activate the mTOR “switch” to allow for creation of new and upkeep of existing muscle protein (Columbus et al., 2015; Ham et al., 2014).

Our ability to activate muscle growth and repair decreases as we age, leading to a loss in strength and ability to perform physical activities

It has been shown that as we age, our ability to stimulate this mTOR complex is reduced which, in turn, reduces our ability to repair and replace protein in muscle tissue. This is thought to be because of a concept called anabolic resistance, which refers to a decreased sensitivity to insulin throughout the body as we get older (Yoon, 2017).

This helps explain why muscle mass gradually starts to decrease as we get older. After the age of 50, approximately 1% of muscle mass is lost annually.

We lose up to 40% of the cross-sectional area of our muscles between the ages of 20 and 60 years; this continues each year thereafter as a result of developing resistance to protein synthesis stimulation (Vandervoot 2002).

Cross-sections of muscle showing the impact physical inactivity can have on muscle mass during ageing. Taken from the webinar Active Ageing: Distinct Nutrition, Distinct Innovation? McLeod M., Breen L., Hamilton D.L., Philp A. (2016) Live strong and prosper: the importance of skeletal muscle strength for healthy ageing. Biogerontology 17(3):497-510.

A loss of between 30-50% of our total muscle mass by the age of 80 often translates into a severely reduced ability to perform day-to-day activities like climbing stairs, standing, or walking.

Increased protein intake can counteract age-related muscle loss

Increased protein intake may be able to counteract this decreased insulin sensitivity that comes with ageing, which is called anabolic resistance. For young children and adults (< 30 years), the mTOR complex is mostly stimulated by insulin, meaning less leucine (and thus protein) is required to be consumed in each meal (approx. 1g leucine per meal). As individuals age, the sensitivity of the mTOR complex to insulin reduces and this means that more leucine (2.5g per meal) is required to sufficiently stimulate muscle protein synthesis. This means older adults need to consume more protein than younger adults and children to maintain muscle mass (Yoon, 2017).   According to a study by Moore et al. in 2014, older adults need 68% more protein to maximize protein synthesis (i.e. activate mTOR).

The dietary recommendation for protein intake from the World Health Organisation is 0.8g per kilogram of body weight (BW) per day, which is equivalent to around 64g per day for the average male and 55g per day for the average female. This amount is thought to meet the requirements of healthy adults, but there is scientific debate about whether this recommendation should be greater in older adults.

In a study by Campbell et al. (2001), 10 healthy male individuals, aged between 55-70, were fed the Recommended Daily Allowance (RDA) for protein (0.8g/kg BW) over a 14 week period and the results showed that all subjects, bar one, displayed a loss of muscle in their mid-thigh muscle zones. It was concluded that the RDA may not be adequate for the metabolic and physiological need of virtually all ageing people.

How much more protein is needed?

As a result of studies like the one mentioned, groups such as the European Society for Clinical Nutrition and Metabolism (ESPEN) and the International PROT-AGE Study Group have proposed new recommended requirements for protein intake (Bauer et al., 2013; Deutz et al., 2014). They concluded that for healthy individuals over the age of 65 the recommended dietary protein intake should be increased to 1.0 – 1.2g protein/kg BW.

This would be an increase of 25-50% in the total amount of protein needed in a day for older adults, equivalent to daily intakes 80-93g per day for the average male and 69-83g per day for the average female.

Results from clinical studies have supported these higher recommendations with one such study by Houston et al. (2008) showing that ageing adults who had a daily protein intake of 1.1g protein/kg BW lost 40% less muscle over the course of three years when compared to those who were consuming the RDA value of 0.8g/kg BW.

Opportunity: increase both protein intake and frequency

Despite needing more protein at ages 50+, people generally tend to consume less protein as they age. For example, in the United States, men over 70 years old tend to eat around 20% less protein per day than males who are 19-50 years old.

To help people stay active and independent as they age there’s an opportunity for the food and beverage industry to find ways to add protein into the diets of healthy agers. The amount of leucine needed to activate muscle growth and repair is thought to be equivalent to around 25-30g of high quality protein at a single eating occasion.

This means planning meals, or creating foods and beverages, with 25-30g of protein if they are meant to be consumed alone (e.g. meal replacement beverages), or 10-15g of protein if they are intended to be consumed at a meal or with other foods, is one way to improve muscle health. Choosing flavors and language that appeal specifically to active agers is also important.

Turn the “switch” on multiple times per day – opportunities for breakfast, snacks, and lunch

The more times the mTOR “switch” is activated per day via consuming protein, the more likely we are to grow or retain our muscle mass (Layman 2009). Many people consume low amounts of protein early in the day, such as at breakfast, mid-morning, and lunch, and consume a protein-heavy evening meal. This means that muscle growth is likely to be only activated once per day. By shifting  protein toward the early parts of the day, we can activate this “switch” more times per day, leading to a greater retention of muscle through diet alone.

For some people, this doesn’t necessarily mean consuming more total protein in a day is required. Instead,  it can be effective to redistribute protein intake to be more equal across the dayparts. Adding protein to breakfast foods and mid-morning snacks is a great way to promote more protein intake throughout the day. This could include fortifying common breakfast foods like oatmeal, cereals, yoghurts, etc., or creating new foods or beverages to consume alongside a meal.

Different dietary trends come into popularity at various stages and recent times have seen the resurgence of the low carbohydrate – high fat diet (LCHF) diet, this time in the form of ‘the ketogenic diet’.  This diet encourages less than 10% of total calories from carbohydrate and more than 70% of total calories from fat. This is a stark difference compared to normal dietary recommendations, which encourage 40-65% of calories from carbohydrate and 20-35% of calories from fat.

What are the differences between the Keto diet (low-carbohydrate, high-fat (LCHF)), and a traditional diet (high-carbohydrate, low-fat (HCLF))?

• Low-Carbohydrate, High-Fat (LCHF) diets are defined as a carbohydrate intake of less than 25 percent of total daily caloric intake and a fat intake ranging from 60 up to 80 percent of total daily caloric intake (Burke et al. 2017; Burke, 2015; Chang et al, 2017;).

• High-Carbohydrate, Low-Fat (HCLF) diets are the more “traditional” dietary pattern for endurance athletes, composed of a carbohydrate rich intake of approximately 45 to 65 percent or more of total daily caloric intake (about five to 12 grams carbohydrate/kilogram of body weight/day) and a fat intake of 20 to 35 percent of total daily caloric intake (Manore, 2005; Burke, 2015).

The LCHF diet is not a new invention – the Atkins diet was previously highly popular using a similar concept. However, with its highly promoted claims relating to its effect on weight loss and other health benefits, it has increased in popularity once again, especially in the athletic community (Burke, 2015; Chang et al, 2017; O’ Neal et al, 2019; Thomas, 2019).

How do diets like Keto impact exercise?

So, does this mean that LCHF diets are the way forward for our endurance-based athletes? Not exactly – there is no one size fits all answer because an athlete’s diet is influenced by many factors.  The sport performed, training frequency, personal food preference, food allergies and intolerances and whether the athlete is on or off season in their training cycle all impact their nutritional needs.  The purpose of this article is to provide some clarity by taking an evidence-based approach to the question and analysing best practice for an endurance athlete.

Type of exercise determines which fuel our bodies use

Low intensity exercise uses a mix of carbohydrate and fat as fuel sources, the majority coming from fat. High intensity exercise uses carbohydrates as the major fuel source, meaning low carbohydrate diets are less appropriate for this type of activity. It’s thought that low carbohydrate, high fat diets like Keto could be helpful for low intensity exercise, although research to date has not supported this idea.

During exercise, the body uses a variety of fuel sources i.e. carbohydrate or fats. The type of fuel used depends on the duration and intensity of the session. Low intensity sessions (such as an easy paced 30-60-minute leisure walk or run) are predominantly aerobically based during which the body would use a combination of both carbohydrates and fats. During higher intensity sessions (such as shuttle runs or hill sprints when breathing is difficult, and an athlete is working at or close to their maximum capacity) the body will use carbohydrate as its preferred source for fuel. The fuel used in moderate intensity exercise sessions is individual and is determined by the athlete’s adaptations from their aerobic training over time. This is because one becomes better at oxidising (using) fats for energy via training and can therefore rely less on carbohydrates during moderate intensity exercise sessions (team field sports, for example).

Low carbohydrate diets are not ideal for high intensity exercise, but could they work for endurance exercise?

Current research (Burke, 2015; Burke et al., 2017) suggests that LCHF dietary intake may have a significant negative effect on performance output once the intensity of the activity increases (i.e. sprinting, or hard, short bursts). Conversely, LCHF diets have been shown to help reduce an endurance athlete’s response to fatigue at a low intensity– what this means is that the athlete would be able to run for longer at a suboptimal pace, indicating a potential benefit to the endurance athlete. However, just “going” is not the goal of any athlete looking to achieve optimal performance hence the need to determine a diet that will also increase performance.

A four-week investigation conducted by Burke et al. (2017) looked at the effects of a ketogenic low carbohydrate, high fat (LCHF) diet in comparison to high carbohydrate (CHO) low fat (HCLF) dietary pattern. The study specifically focused on fuel adaptation, metabolism and performance of elite race walkers during 3 weeks of intense training.

There were three diet groups;

1. A high carbohydrate diet (HCLF)- 60-65% of energy came from carbohydrates, 15-20% protein, 20% fat; consumed daily and before during and after training (9 women).
2. Periodized CHO group: Same composition as HCLF, at different intervals according to training demands and fuel needs with some training sessions focused on high CHO availability (high muscle glycogen, CHO feeding during session) and others with low CHO availability (low pre-exercise glycogen, overnight fasted or delayed post-session refuelling) (10 women).
3. A LCHF diet: 75-80% fat, 15-20% protein, <50g/day CHO (10 women).

The research found that there were no benefits to performance in the low carbohydrate diet consumed by group 3. In fact, performance levels were not seen to improve in the LCHF group despite preforming 3 weeks of intensified training, in comparison to the athletes assigned to the other dietary patterns who all demonstrated significant performance improvements after the 3 weeks of intensified training. It was also found that there was an increased need for more oxygen to perform the same amount of work when an athlete is fuelled on LCHF. Interestingly, an improvement in performance was achieved by the carbohydrate groups (diets 1 and 2). Earlier research by Burke et al. (2015) also found that cycling and sprinting performance was reduced when the athlete consumed a LCHF diet.

A study by Lambert et al. (1994) did show that a LCHF dietary intake may be effective in endurance athletes. Five endurance trained elite cyclists were required to consume, in random order, a HCLF diet (high carbohydrate (74%) and low fat (12%)) or a LCHF diet (high fat (67%) and low carbohydrate (7%)) for a two-week period. For training output, they were required to exercise to exhaustion at 60% of their VO₂max (their maximum aerobic exercise capacity). The participants prescribed the LCHF doubled their time to exhaustion in moderate intensity exercise – 60% of their VO₂ max, which was longer in comparison to the HCLF diet. In other words, they were able to keep going for longer on the LCHF dietary protocol. These studies support the concept that LCHF diets may enable athletes to keep going for longer but only at lower intensities.

Why don’t all studies show improvements in endurance performance on a LCHF diet?

The main purpose and theory behind the use of LCHF diets in endurance activities is that this style of dietary management would allow an endurance athlete to alter the type of fuel (carbohydrates or fats) that they rely on during exercising. In theory, improving an athlete’s ability to utilize fat during exercise would allow them to rely less on their limited carbohydrate stores during exercise and more on their nearly-limitless stores of fats. If this was to work for a given endurance athlete, they would be capable of going for longer without hitting the metaphorical wall of fatigue, exhaustion, dizziness, and lethargy associated with depletion of carbohydrate stores during prolonged, intense exercise/ race. In theory it works very well. Unfortunately, studies exploring the effects of fat adaptation on exercise performance in the athletic population are limited and the question remains unanswered. However, what we do know is that looking through the evidence base to date, a combination of carbohydrates (generally normal-high levels) and fats for fuel (so not fat adapted) have yielded better performance results for the athlete in endurance-based training and sport events trials (Bartlett et al. 2015; Burke et al. 2011; Stellingwerff 2013).

 If low-carbohydrate diets don’t improve performance in endurance exercise, what are other uses they might have?

During off season or sustained periods of lighter training (often used to give the body a break from continuous high levels of training), the use of a LCHF diet can work very well to help maintain weight or reduce fat mass with the goal of an improved body composition for competition. LCHF diets paired with a calorie-controlled intake provide a promising method of helping control body weight and fat mass while maintaining lean body mass (Volek et al., 2002; Zajac et al, 2014). However, this is more suited when making weight is a consideration for the athlete and not advised when performance is a priority. For the recreational athlete, where performance (and competition) is not the main objective, the LCHF dietary pattern may be suitable for maintaining physique while still reaching training goals.

So, what’s the verdict?

The research to date favours the use of a more traditional, HCLF dietary approach for overall endurance performance. However, individual differences between athletes should also be a consideration and carbohydrate intake should meet the purpose and need of training/performance.

There is no one-size fits all approach; there is no “perfect” or “ideal” dietary approach for endurance athletes. Few athletes understand exactly why and how adjusting their dietary intake in line with their training programme can optimise their performance i.e. increased carbohydrates on heavy training or double session days will increase performance and recovery while reducing carbohydrates on rest day is more beneficial.

“Is soy unhealthy or healthy?” is the common question this article will answer based on recent science.

What is soy?

Soy is a plant that originated in Asia and is now grown in many places around the globe. The plant’s beans (the soybeans) can be eaten on their own (like edamame) or used to make soy foods (like tofu, miso, tempeh, soy milk and soy sauce). Soy flour and protein are also added to many prepared foods, from breads to breakfast cereals to energy bars.

Soy contains high amounts of isoflavones, which are phytonutrients. Phytonutrients are compounds found in plants that have actions in our body, but are not vitamins or minerals. Isoflavones belong to a group of substances called phytoestrogens (plant estrogens). As the name implies, they can have certain actions in our body that are similar to the human hormone estrogen, but with much weaker effects. Because estrogen can play a role in breast cancer development and survival, there have been many questions raised about the risks and benefits of diets high in soy.

Is soy unhealthy or healthy?

The main takeaway from published research is that soy is a nutritious food. Science shows that typical consumption of soy (1-2 servings of soy-based foods or drinks per day) in a balanced diet is unlikely to cause harm, and may provide health benefits, to the general public.

Soy as a food is:

• Low in calories and saturated fat
• Rich in high quality protein, especially among plant protein sources
• High in fiber

Just 100 grams of raw soybean (less than half of a cup) contains 13 grams of protein, 4 grams of dietary fiber, 3 grams of polyunsaturated fatty acids, as well as 20% of our daily value of calcium and iron, 48% of our daily value of vitamin C, and 18% of our daily value of potassium (USDA Food Composition Database). Dietary guidelines around the world encourage most of these are nutrients in the diet, solidifying soy’s role in a healthy diet.

These traits make soy a great food to include in a balanced diet. In the sections below, we review the specific roles soy has in health.

It is important to note that, although research shows that consuming soy can improve some health outcomes, soy is considered an allergen and would be inappropriate to consume for those with a diagnosed allergy to soy.

Soy as a plant protein option

Soy is a healthy source of plant protein for most people.

When it comes to choosing a plant protein source, protein quality is one of the key deciding factors. Protein quality is a measure of how the amino acid content of a protein measures to what the human body needs, as well as how digestible that protein is. As shown in the graph below, soy is one of the few plant-based proteins that is equivalent in quality to animal-based proteins.

This is because soy contains all nine essential amino acids in significant amounts. This can be useful for vegans, as other vegan sources of protein are often low in the essential amino acids lysine and methionine. It can also be helpful in achieving protein claims in certain parts of the world.

For this reason, soy is often a great choice for a plant-based protein in foods and beverages.

Soy, Estrogen, and Cancer

• Overall evidence from human studies shows that consuming soy doesn’t increase the risk of cancer
• Recent research has found that consuming 1-2 portions of soy per day does not cause any harm for breast cancer survivors
• Soy is considered to be safe for men to consume and does not affect testosterone concentrations

What is the relationship between soy and development of breast cancer?

It is not likely that eating moderate amounts of soy foods increases the risk of breast cancer. The majority of high-quality studies and analyses have found that eating soy foods does not increase risk, even when eaten at levels much higher than those typically consumed in countries like the United States (Trock 2006, Wu 2008).

Many studies suggest that soy may help protect against breast cancer (Trock 2006, Wu 2008). Results from an analysis that combined findings from multiple studies in Asian populations found that soy may have a protective effect on breast cancer incidence. However, when the same analyses were done in studies of US and other Western populations, there was no link between soy and breast cancer risk (Wu 2013). It seems the benefit only comes with a pattern of intake that is seen in most Asian countries, where women begin eating soy early in life and eat it in amounts many times greater than typically seen in the U.S. In Japan, for example, soy intake ranges from 38 g to around 78 g per day, equivalent to 26 to 54 mg isoflavones. In the U.S., soy intake ranges from less than 1.5 to 4.3 g per day, or 1 mg to 3 mg isoflavones (Nagata 2010).

As a breast cancer survivor, is soy safe?

Current studies suggest that eating moderate amounts of soy foods is safe for breast cancer survivors (Shu 2009, Cassileth 2012, Nechuta 2012). Evidence suggests that a diet high in soy may improve survival and lower the risk of recurrence in women with breast cancer. The benefits don’t appear to be limited to Asian populations, either.

One analysis combined data from three large, long-running studies of survivors from both Asian and Western countries. It found that women who ate at least 10 mg of soy isoflavones per day after a breast cancer diagnosis had a 25 percent lower risk of recurrence compared to those eating less than 4 mg soy isoflavones per day (Nechuta 2012).

An analysis of 6235 breast cancer survivors found that, after 9.4 years after diagnosis, soy intake did not increase risk of mortality. The study found that those with the highest soy consumption had a trend toward reduced risk of mortality, although these results were not statistically significant (Zhang 2017).

Soy and Heart Health

Research has shown soy intake  has a role in reducing LDL and total cholesterol, both of which are outcomes linked to improved heart health.

A scientific review of 46 studies on soy’s role in heart health was published in 2019 (Mejia 2019). In the study, researchers found that consuming soy protein at a dose of ~25 grams per day led to a decrease in LDL cholesterol of 4.76 mg/dL (3-4%) and a decrease in total cholesterol of 6.41 mg/dL over 6 weeks, which could be considered a clinically significant reduction. Around 75% of the studies reviewed showed a positive effect for consuming soy protein, according to the researchers.

This review is important in helping solidify the role of soy protein in heart health and counter the unwarranted negative perception of soy among many consumers.

References

Cassileth BR, Yarett I. Soy Phytoestrogens and breast cancer: An enduring dilemma. The ASCO POST. 3(11), 2012.

Dong JY, Qin LQ. Soy isoflavones consumption and risk of breast cancer incidence or recurrence: a meta-analysis of prospective studies. Breast Cancer Res Treat. 125(2): p. 315-23, 2011.

Mejia, Sonia Blanco, Mark Messina, Siying S Li, Effie Viguiliouk, Laura Chiavaroli, Tauseef A Khan, Korbua Srichaikul, Arash Mirrahimi, John L Sievenpiper, Penny Kris-Etherton, David J A Jenkins, A Meta-Analysis of 46 Studies Identified by the FDA Demonstrates that Soy Protein Decreases Circulating LDL and Total Cholesterol Concentrations in Adults, The Journal of Nutrition, Volume 149, Issue 6, June 2019, Pages 968–981, https://doi.org/10.1093/jn/nxz020

Nagata C. Factors to consider in the association between soy isoflavone intake and breast cancer risk. J Epidemiol. 20(2): p. 83-9, 2010.

Nechuta SJ, Caan BJ, Chen WY, et al. Soy food intake after diagnosis of breast cancer and survival: an in-depth analysis of combined evidence from cohort studies of US and Chinese women. Am J Clin Nutr. 96(1):123-32, 2012.

Shu XO, Zheng Y, Cai H, et al. Soy food intake and breast cancer survival. JAMA. 302(22):2437-43, 2009.

Trock BJ, Hilakivi-Clarke L, Clarke R. Meta-analysis of soy intake and breast cancer risk. J Natl Cancer Inst. 98(7):459-71, 2006.

Wu AH, Yu MC, Tseng CC, Pike MC. Epidemiology of soy exposures and breast cancer risk. Br J Cancer. 98(1):9-14, 2008.

Wu AH, Lee E, Vigen C. Soy isoflavones and breast cancer. Am Soc Clin Oncol Educ Book. 102-6, 2013.

Zhang, Fang Fang et al. “Dietary isoflavone intake and all-cause mortality in breast cancer survivors: The Breast Cancer Family Registry.” Cancer vol. 123,11 (2017): 2070-2079. doi:10.1002/cncr.30615

How social isolation impacts eating and nutrition

Food and social interaction are deeply intertwined. Food is often shared and represents a way of connecting with others: eating together at mealtimes, cooking for loved ones or feasting together during celebrations. Social distancing means that these social aspects of eating have been temporarily removed for people living alone. In addition, feelings of loneliness, reduced accessibility to food and changes to normal daily routines can pose nutritional challenges.

Research shows that social isolation and loneliness are associated with reduced appetite (2), lower food intake (3), reduced physical activity (4) and increased risk of under-nutrition among older people (5). On the other hand, while under-consumption of food is more common in socially isolated older adults, some individuals may respond to isolation and COVID-related anxiety by using food as an emotional coping mechanism leading to overeating. In addition to affecting how much we eat, isolation also appears to affect what we eat. Socially isolated older adults consume fewer fruits and vegetables (4) and eating alone more frequently is associated with lower dietary variety (6). Cooking for one may reduce the motivation to cook and enjoy a “proper meal” (7) and instead older adults may opt for quick, nutritionally incomplete meals like tea and toast.

Mitigating the impact of isolation on health

Currently, staying at home is critical to protect our health and the health of others. However, it is imperative that we engage in healthy behaviours at this time in order to mitigate the harmful effects of the physical inactivity and isolation that can accompany staying at home. Eating well, particularly in combination with physical activity, can prevent malnutrition and nutrient deficiencies, improve our feelings of well-being, help preserve muscle mass, strength and mobility, promote gut health, support the immune system and lower the risk chronic illnesses and infectious diseases (8).

Tips for eating well during social isolation

1. Take steps to combat loneliness to help prevent the adverse effects on appetite and food intake.

-Connect virtually – make frequent telephone or video calls to family and friends

-Structure your day and your sleeping habits – having a daily routine can provide a sense or normality and control

-Keep busy – brainstorm tasks and activities you can do from home (exercising, gardening, reading, cleaning, crosswords etc.)

2. Maintain good eating habits

-Keep a regular meal pattern – this can provide structure to your day and can help to create awareness around how much and what you are eating

-Plan meals ahead of time, and try to include high protein foods, whole grains, fruits, and vegetables at each meal

-Mix it up – try to eat a variety of different food rather than sticking to the same meals each day

3. Stay motivated when cooking for one

-Have a virtual lunch or dinner date with a friend or family member

-Bulk cook easy-to-prepare, one-pot dishes like curries, stews and soups when you’re feeling energetic. Freeze individual portions for days when you don’t feel motivated to cook.

-Keep a well-stocked food cupboard so that you always have some ingredients to hand to make a simple meal

4. Check in with your appetite and your food intake

-If you find your appetite is lower than normal and / or you are unintentionally losing weight, try eating small, nourishing snacks frequently (e.g. high protein drinks, yogurts, crackers and cheese, or dried fruit and nuts) and add extra calories to meals (e.g. add milk, skimmed milk powder or cream to soups and mashed potatoes, or use full fat dairy products)

-Include physical activity in your day 

-Speak to your doctor if you are worried or continue to lose weight

How companies can adapt these strategies to improve nutrition of older adults

Managing Director Sue McVie of Oakhouse Foods, which provides frozen, prepared meals direct to the homes of older adults, outlines some ways she sees companies can bring the strategies from this article to life.

Loneliness is a significant issue amongst the elderly consumer and can result in loss of appetite and poor nutrition. From a nutritional perspective, we know that our customers’ appetites can be small. Some strategies that can be used to help maintain nutritional balance include more frequent, smaller portions like ‘mini-meals’ and ‘lighter bites’, as well as making sure there is a diverse range of foods offered to encourage dietary variety.

For companies looking to adapt dietary strategies to improve nutrition of older adults, finding ways to increase dietary variety, nutritional density for smaller appetites, and frequent engagement can be key for success.

‘Deconditioning’ and the potential loss of muscle mass and strength during social isolation

Currently many are being advised to “stay at home” and to minimise our physical contact with others. Following this advice is the best thing we can do to protect our health and the health of others.  For many people, staying at home may lead to a reduction in time spent walking and engaging in other physical activities. Even relatively short periods (~2 weeks) of very low physical activity / low daily step count (<2,000 – 3,000 steps per day) are known to adversely affect skeletal muscle health (1, 2). This is of particular concern among older adults who are already at high risk of muscle mass and strength loss. Unlike younger adults who “bounce back” relatively easily from transient periods of inactivity, recovery in older adults is slow and may be incomplete (1, 2). As such, these periods of inactivity may have long lasting negative effects on physical function and mobility. Fortunately, simple measures can be taken to minimise the deterioration in muscle health.

Cross-sections of muscle showing the impact physical inactivity can have on muscle mass during ageing. Source: McLeod M., Breen L., Hamilton D.L., Philp A. (2016) Live strong and prosper: the importance of skeletal muscle strength for healthy ageing. Biogerontology 17(3):497-510.

Nutrition and maintaining muscle mass for older adults

What we eat can help us to maintain our muscle health while remaining at home, especially when combined with resistance exercise. Protein-rich foods combined with a balanced diet of whole grains, fruits, and vegetables can be an important part of staying healthy and maintaining mobility.

Protein power

Compared to younger adults, older adults are less efficient at using the protein they eat (found in foods like milk, yogurt, fish, eggs, meat, beans, nuts) to build new muscle (3). This means that older adults need more protein in their diets than younger ones and not eating enough protein can contribute to muscle loss.  Expert groups recommend that healthy older adults should consume 1.0 – 1.2 g of protein per kilogram of body weight per day to help preserve muscle (4, 5). It is particularly important to ensure that older adults continue to consume adequate amounts of protein while isolating. Some tips include:

• Prioritise protein – as physical activity levels fall during social distancing, the number of calories we burn per day decreases and appetite may also decline. Prioritizing protein-rich foods can help maintain a similar protein intake as before social distancing was introduced.
• Choose high quality sources – higher quality protein sources (e.g. milk, yogurt, fish, eggs, meat, poultry) are better at stimulating muscle growth compared to lower quality protein sources (6). Getting a moderate-size serving of high quality protein (25-30 grams) at each meal can improve muscle retention.
• Boost breakfast – breakfast tends to be low in protein, so breakfast foods are an opportunity to boost daily protein intake. Making porridge with milk rather than water, adding Greek yogurt to muesli or a smoothie, making an omelette or scrambled eggs, or drinking a glass of milk alongside your meal are all common ways of boosting protein at breakfast.
• Pair protein with exercise – the exercise will make muscles more efficient at using the protein from the meal to build new muscle (7).
• Pre-bed protein – consume a protein-rich snack (e.g. Greek yogurt, cottage cheese) before bed to boost muscle building rates overnight (8).

Calories count

Studies indicate that consuming either too few or too many calories over several weeks can worsen muscle loss during periods of inactivity (9, 10). It is normal for people to have a slightly lower appetite when they are less active than usual at home. However, if appetite drops considerably and results in weight loss, this may accelerate muscle loss.

Small, nourishing snacks frequently throughout the day to give a constant source of protein (e.g. milky drinks, yogurts, crackers and cheese, custard) and add extra calories to meals (e.g. add milk, skimmed milk powder or cream to soups and mashed potatoes, use full fat dairy products) are two ways to prevent appetite-related weight and muscle loss.

Alternatively, some people may find that, despite decreased activity levels, they are eating more than usual due to boredom or stress. In this case, eating plenty of fruit and vegetables which are low in calories and high in fibre can people stay full. Prioritising protein-rich foods as discussed above and reducing intake of high-calorie, low protein foods (e.g. biscuits, chocolate, crisps, sweets, butter) can help reduce risk of weight gain.

Physical activity to maintain muscle mass

Use it or lose it

The best way to protect muscles against the adverse effects of inactivity is to keep using them. Resistance exercise, defined as exercising muscles against an external force (e.g. weights, resistance bands, our own body weight), is by far the most potent strategy to maintain muscle mass and strength. Research has shown that incorporating resistance exercise during periods of reduced activity can attenuate or even abolish the decline in muscle mass (11, 12) and strength (12, 13). Importantly, even relatively low amounts of resistance exercise appear to be effective once performed regularly (e.g. every other day) (12). Although most older people may not have access to resistance training equipment at home, body weight exercises can be performed (e.g. sit-to-stands, wall push ups, leg extensions from a chair). It is important for people to check with their doctor to find out if they have any contra-indications to exercise or if there are any reasons to modify their workout.

Reduce sedentary time – exercise “snacks”

Engaging in physical tasks around the house each day like gardening, active chores (e.g. sweeping, hoovering) or even walking around while on the telephone can help to minimise inactivity while staying at home, thus reducing the detrimental effect on muscle.

People can also break up prolonged periods of sitting with “exercise snacks”. Exercise snacks are short bursts of exercise spread throughout the day (e.g. briskly climbing the stairs during ad breaks on TV). A recent study reported that performing brisk stair climbing (approximately 20 seconds of climbing per “snack”) three times per day, three days per week, improved fitness and leg power in sedentary people (14). Therefore, exercise snacks like these may help to reduce declines in fitness that occur during periods of inactivity.

Stay on track

Staying motivated can be difficult, especially when we are isolated at home and separated from loved ones. To maintain muscle health it is important to keep up the exercise and healthy eating for the duration of isolation. Some tips to help stay motivated include:

• Set goals about when and where to do the exercise (15)
• Choose activities you enjoy (16)
• Monitor your exercise using diaries or apps or ask a friend or family member to monitor you (15)
• Plan your protein-rich meals for the week ahead and make a shopping list
• Keep a stock of protein-rich foods (e.g. tinned fish, freeze extra poultry, meat and fish)
• Experiment with new protein-rich recipes to keep things interesting

To learn more about how COVID-19 is affecting the food and beverage industry, including changes in consumer preferences and purchasing behaviours, visit Kerry’s COVID-19 resource page.