The human body is composed of approximately 55 – 60% water, and it constitutes 95% of the eyes, 83% of blood, 75% of muscles and the brain, 22% of bones.  This water is distributed between intracellular fluid (ICF), which makes up about two-thirds of the body’s water, and extracellular fluid (ECF), which constitutes the remaining one-third.  Water moves between the ICF and ECF by osmosis, which is crucial for enabling cellular function and transport of nutrients.

Water has several vital functions in the body, such as acting as a catalyst, lubricating and cushioning tissues, and regulating temperature.  It also helps deliver oxygen around the body, facilitates saliva production, and enables the brain to make hormones and neurotransmitters to transport signals around the body.

Hydration and Exercise Performance

Optimal hydration is critical for maintaining good performance during exercise, maximising heat transfer, maintaining mood, and facilitating post-exercise recovery ¹.  Water is not stored in the body in dedicated reserves, instead water levels are regulated through constant intake and output.  Water balance in the body is influenced by factors such as exercise, climate, and nutrition.

Increased physical activity results in more water being lost through perspiration, making it crucial to drink extra fluids to stay hydrated.  Therefore, consistent and sufficient fluid intake is vital for meeting the body’s hydration requirements ¹.

Dehydration occurs when the body loses water, with losses of greater than 2% ².  Being thirsty means the body is already in a state of dehydration ³.  Depending on the amount of body fluid lost, dehydration can be mild, moderate, or severe.  For instance, dehydration can lead to impaired concentration, increased reaction time, and anxiety, all of which negatively impact exercise performance and recovery ^4,5.

Research indicates that nearly 71% of adults do not meet the recommended daily fluid intake guidelines ⁶, and people who exercise, whether recreational or competitive, often do not adequately replenish fluids lost during exercise ³.  This condition, known as Exercise-Induced Dehydration (EID), can be estimated by measuring body mass loss during exercise, which is also known as a person’s Sweat Rate ⁷.

Sweat rate can significantly differ between individuals and even within the same individual under different conditions ⁸.  Factors such as environmental temperature, exercise intensity, and individual physiology can affect sweat rate ⁸.  Monitoring sweat rate helps individuals, especially athletes, to know their hydration requirements and tailor their fluid intake to optimise performance and prevent dehydration.  To calculate Sweat Rate, the following factors need to be measured – weight loss, volume of fluids consumed, urine loss and the duration of exercise – as shown in the following diagram ⁹.

Hydrating Before, During, and After Exercise

Starting exercise in a hydrated state is essential ¹⁰.  Indicators such as thirst, body weight, and urine colour can help monitor hydration status.  The type of fluids consumed before, during, and after during exercise significantly influences hydration and the body’s ability to absorb water efficiently ^1,11.  By drinking too much water due to exercise, sodium can be depleted from the body, which is known as Exercise-Associated Hyponatremia (EAH).  Causes of EAH is usually by individual sweat loss, excessive intake of hypotonic fluids, and hormonal imbalances, which occur more frequently at longer competitive distances.  However, EAH has been reported in non-endurance sports, such as rowing, shorter races, team sports, and yoga ¹².  EAH, if left untreated or inadequately treated, leads to individuals experiencing altered mental status, seizures, and even coma ¹².

For recreational exercise, there is no need to overconsume fluids before activity, but keeping hydrated is important.  Pre-hydrating with fluids, in addition to normal meals and fluid intake, should start at least several hours before exercise.  The American College of Sports Medicine (ACSM) recommend drinking 500ml of fluid or, going by body weight, 5 – 7ml of fluids per kilogram of body weight ^1,11.  Including hydrating foods like fruit or fruit juice in pre-activity meals can also help.

The goal during exercise is to prevent a 2% loss of body mass.  Fluids consumed should approximately replace sweat volume losses, avoiding both under- and over-consumption.  Thirst may be delayed, so it can be helpful to calculate personal sweat rates to develop a hydration strategy based on an individual’s needs ¹³.  Fluids should be cooler than ambient temperature and readily available to allow adequate volumes to be ingested with ease and with minimal disruption to exercise ^1,11.

During intense exercise lasting longer than 1h, carbohydrates should be ingested at a rate of 30 – 60 grams per hour to delay fatigue and, hence, sustain performance.  This rate can be achieved by drinking 0.5 – 1l per hour of fluids containing 6% – 8% carbohydrates ¹.  Adding sodium (0.5 – 0.7g /l of fluid) is recommended as it may promote fluid retention and possibly prevent hyponatremia in individuals who drink excessive amounts of fluid ^1,11.

Post exercise, the goal is to replenish fluids and sodium losses which improve recovery, reduce hypohydration symptoms, and decrease post-exercise fatigue.  Individuals needing fast and complete recovery from excessive dehydration can drink approximately 1.5l of fluid per kilogram of body weight lost ^1,9.  Whereas individuals capable of recovering over an extended period can rehydrate by consuming normal meals and fluids if lost sodium is replaced.

Importance of a Personalized Hydration Plan

Fluid loss is directly related to body mass, with the body losing approximately 0.4 – 0.5ml of water per kg of body mass per hour.  Without exercise, the recommended water intake is 30 – 40ml per kg of body mass, equating to 2.1 – 2.5l per day ¹⁴.  However, a universal recommendation for rehydration is challenging due to individual variations in daily water intake, sweat rate, and gastrointestinal tolerance.

Given the importance of hydration before, during, and after exercise and the tendency for the body to become dehydrated, an individualized hydration plan is recommended ³.  A personalized hydration plan supports fluid intake and successfully optimizes hydration status, regardless of environmental conditions and supports recovery.  Additionally, tailored hydration plans have the potential to improve anaerobic power, attention and awareness, and heart rate recovery time ¹⁵.

Summary

The human body relies on water for essential processes such as nutrient transport, temperature regulation, and cellular function.  During exercise, maintaining optimal hydration is crucial to prevent performance impairments and facilitate recovery.  Research highlights that even mild dehydration can significantly impact exercise performance, leading to negative effects on mood, cognitive function and physical outcomes.

Individuals often fail to replenish fluids adequately, and their fluid needs can vary significantly.  This emphasizes the need for personalized hydration strategies which consider individual sweat rates, exercise intensity and duration, environmental conditions, and personal tolerance.  Monitoring hydration status through indicators like body weight and urine color, and consuming appropriate fluids before, during, and after exercise, are key components of such a plan.

To read about why keeping hydrated is important for people’s health and wellbeing, click here.

This series, hosted by John O’Connor, Head of Nutrition for Kerry GAA, and Aoife Marie Murphy, Senior Sustainable Nutrition Manager at the KHNI, highlights practical tips and insights into crafting balanced meals that cater to the high energy demands of youth athletes no matter what sport they play.

In the third and final video of the series, John and Aoife visit young female athletes at Fossa GAA club in Co. Kerry, Ireland, highlighting the distinct nutritional needs of female athletes and recipes to support their training and performance.

The Importance of Nutrition for Female Athletes

Becoming a successful athlete doesn’t only depend on rigorous training; it also depends heavily on maintaining proper nutrition.  For young female athletes, this is even more crucial as they are in a significant phase of growth and development as well as hormonal fluctuations across the menstrual cycle.

Good and appropriate nutrition can support female athletes to perform at their best, build strength in bones and muscles, support recovery, limit injury and illness and helps to build confidence.

The Female Athlete Triad

There are 3 priorities for female athletes to consider when training and competing in sport.

1. Fuelling appropriately according to energy demands is important for young female athletes as it ensures they have the energy necessary to perform at their best during training and competitions.  Proper nutrition not only supports physical growth but also helps in building strength, aiding recovery, and minimising injuries.  Under-fuelling is common in female athletes and this can lead to poor health consequences such as amenorrhea (missed periods), fatigue, poor concentration, weaker bones and reduced immunity*.
2. Hormonal health is another key factor, as fluctuations during the menstrual cycle can affect performance and energy levels.  Menstrual cycle tracking can support females to optimise their training schedules.  Ensuring adequate intake of key nutrients such as iron and vitamin C helps in maintaining hormonal balance and easing PMS symptoms.
3. Meal timing plays a significant role in enhancing performance.  Eating the right foods at appropriate times before, during, and after training can maximize energy availability and support efficient recovery, thereby enhancing overall athletic performance.

*For more detail on fuelling and the nutritional requirements of young athletes and the pyramid of priorities see previous articles in this series Fuelling Fitness for Young Athletes – Kerry Health And Nutrition Institute, and Demystifying Nutrition for Young Athletes – Kerry Health And Nutrition Institute

Hormonal Health for Female Athletes

Over the course of the menstrual cycle, there are distinct fluctuations in hormones.  These hormones not only influence your monthly cycle, but also your body temperature, metabolism, hunger and food cravings.

Tracking the menstrual cycle is the first step for female athletes to be more informed about their bodies and what is normal for them.  This allows for proactive alterations in diet and exercise to manage PMS symptoms, support energy levels, food cravings, mood and sleep.

The menstrual cycle is divided into four phases: menstruation, the follicular phase, ovulation, and the luteal phase.  Each phase has unique hormonal changes, physical symptoms, nutrient requirements, and emotional states.

The following information is based on a 28 day cycle, while anything between 21 and 40 days is considered normal.

Menstruation / Period (Typically days 1-5):

• • Oestrogen and progesterone levels will be low
  • Many experience fatigue and PMS symptoms, such as cramps.
  • Lower Energy, therefore choosing lower intensity training regimes can be helpful at this time.

Nutrition Focus: Iron

Iron deficiency anaemia is common for females due to the blood loss associated with menstruation, therefore increasing intake of food sources of iron is important to replenish this iron lost as well as to combat fatigue.  Iron-rich foods include both animal (haem iron) sources, eg. liver and red meat, and plant based (non-haem iron) sources eg. leafy greens and legumes.

Incorporating magnesium-rich foods, such as nuts and seeds may relieve migraines and mood swings and incorporating foods rich in omega 3 such as salmon, flax seeds, and avocado, may alleviate cramps.

A missing period or extended/irregular cycle length might be a sign of relative energy deficiency in sport (REDs) which could be a result of over-exercising, under fuelling, or a combination of both.  This might increases risk of injury, illness, and underperformance.

Follicular Phase (Typically days 1-14):

• • Oestrogen levels start to rise peaking just before ovulation (day 14).
  • Energy levels increase gradually and mood improves.
  • May feel more social and extroverted.

Exercise: Following the period, prioritise high intensity training, strength training and competitions as energy levels are highest.

Nutrition Focus: As oestrogen levels increase, choose an overall healthy diet rich in fibre and micronutrients  like whole grains, fruits, and vegetables to support hormonal balance and provide sustained energy.  Include sources of healthy fats such as avocados and fatty fish to enhance mood and cognitive function, and fermented foods such as yoghurt and kimchi for gut health.  Hydration should be prioritized to maximize performance and recovery.

Luteal Phase (Typically days 15-28):

• • Oestrogen drops and progesterone increases, which can increase appetite and cravings, while also impacting digestion.
  • Breast tenderness, bloating, and mood swings.
  • Increased metabolic rate and energy levels can dip.
  • Sleep disruption can be common which can affect irritability and performance.

Nutrition Focus: The increase in metabolic rate can lead to cravings for foods high in carbohydrate and fat.  Prioritise complex carbohydrates which are high in fibre like whole grains and sweet potatoes to stabilize blood sugar levels, prevent constipation and support mood and energy levels.  Incorporate foods rich in vitamin B6 and magnesium, such as bananas and chickpeas, can help alleviate PMS symptoms and bloating.  Increasing foods high in vitamin D and calcium can also reduce PMS symptoms.

Limit salt as this can cause the body to retain more water and exacerbate bloating. Limit or avoid caffeine (especially later in the day) as this is a stimulant that can impact sleep, mood and gut function.

Exercise Focus: Medium to light exercise and active recovery like yoga and walking are best for this time of the month.  If training and competitions are scheduled during this timeframe, choose self-care practices to nurture physical and mental health.

Bone Health for Female Athletes

Adequate intake of calcium and vitamin D plays a critical role in supporting strong bone health for young female athletes.  Most of the skeleton is formed during teenage years and a strong foundation can reduce the risk of osteoporosis later in life, particularly as oestrogen levels decline during menopause.  Incorporating foods like dairy products, leafy green vegetables, and Vitamin D fortified foods or supplements can ensure the necessary building blocks for maintaining bone density and overall skeletal health.

• • A Guide to the Health and Nutritional Needs of Women – KHNI (kerry.com)
  • Menstrual Cycle Nutrition & Physical Activity Recommendations – KHNI (kerry.com)
  • The Hormone Lifecycle Journey: From Menstruation to Menopause – KHNI

See recipes idea’s for young female athletes to obtain the nutrients they need for training.

In conclusion, by understanding and implementing proper nutrition strategies to support hormonal fluctuations, female athletes can unlock their full potential and achieve excellence in their sporting endeavours. 

In the second video of the series, ‘Demystifying Nutrition’, John and Aoife visit young athletes at Kilmoyley and Cillard GAA clubs in County Kerry, Ireland, demystifying some nutritional myths and providing recipes to support their training and performance.

The Pyramid of Nutrition Priorities for Young Athletes

Proper nutrition is key to helping young athletes become stronger, recover faster, minimise injury, and maintain good health.  It also boosts confidence and performance.  The pyramid of nutritional priorities for young athletes is structured to highlight the most important factors for growth and success:

1. 1. Total Calories: The foundation of the pyramid, ensuring athletes get enough energy to support their high energy demands from physical activity and overall growth.
   2. Macronutrients: A balance of carbohydrates, proteins, and fats is critical for fuelling performance, muscle repair, and maintaining overall health.
   3. Micronutrients: Vitamins and minerals play a key role in energy production, immune function, and bone health.  Eating a variety of foods rich in vitamins and minerals (particularly calcium, iron and vitamin D) will helps prevent deficiencies and supports overall health.
   4. Meal Timing: Eating at the right times—especially before and after training and matches—helps maximise energy levels and supports recovery.
   5. Supplements: Supplements should only be used when necessary, complementing a well-rounded diet, not replacing it.  Certain nutrients like omega-3s and vitamin D may require supplementation, as they are harder to obtain from food alone.  However, sports supplements are heavily marketed and should be used cautiously by young athletes.

For more detail on the nutritional requirements of young athletes see article Fuelling Fitness for Young Athletes – Kerry Health And Nutrition Institute

Understanding Sports Supplements

A “food supplement” is defined by EU legislation as any product designed to supplement the normal diet, providing concentrated nutrients or other substances that offer physiological effects.  These products come in various forms, including capsules, tablets, and powders, and should only be consumed in small, measured quantities.

For growing teenagers, the use of sports supplements poses risks.  Over-reliance on supplements can lead to an imbalanced diet, where nutrient-dense foods are overlooked.  Furthermore, many supplements contain ingredients not fully tested for safety in younger populations, potentially causing adverse effects such as hormonal imbalances, liver damage, or dehydration.  Some products may even contain banned substances, which can jeopardise an athlete’s eligibility in competitive sports.  Therefore, it’s crucial for teenagers to focus on a balanced diet and seek guidance from healthcare professionals before considering supplements.

Making Informed Decisions About Supplements

When considering supplements, it’s important to make informed choices.  If any of the following questions cannot be answered with a confident “yes,” it’s advisable to avoid using the product:

• • Is the supplement or active ingredient clinically proven to support health or performance?
  • Is the ingredient lacking in sufficient quantities in whole foods?
  • Has the supplement been checked for prohibited substances?
  • Has the product been batch-tested?

See recipes idea’s for young athletes to obtain the nutrients they need for training.

Conclusion

With the abundance of nutritional advice available, it can be overwhelming for young athletes to navigate their choices.  The pyramid of nutritional priorities offers a helpful framework to prioritize the most important aspects of nutrition for peak performance and recovery.  While marketing and influencers may place undue emphasis on the need for supplements, a food-first approach is always the best strategy.  When supplements are necessary, it’s vital to choose high-quality, well-tested products.

This series, hosted by John O’Connor, Head of Nutrition for Kerry GAA, and Aoife Marie Murphy, Senior Sustainable Nutrition Manager at the KHNI, highlights practical tips and insights into crafting balanced meals that cater to the high energy demands of youth athletes no matter what sport they play.

In the first video of the series ‘Fuelling your Fitness’, John and Aoife visit young athletes at Dingle GAA club in Co. Kerry, Ireland, demonstrating how better nutrition and healthy meals can lead to improved athletic performance.

The Importance of Nutrition for Young Athletes

Becoming a successful athlete doesn’t only depend on rigorous training; it also depends heavily on maintaining proper nutrition.  For young athletes, this is even more crucial as they are in a significant phase of growth and development – often referred to as a growth spurt.  The energy demands of youth athletes are far greater than that of their sedentary counterparts, and even adults. 

This rapid development means that adolescents have complex dietary needs.  Growing athletes need extra energy to stay on top of training and competition.  Good and appropriate nutrition can support adolescent athletes to get fitter faster, build strength in bones and muscles, support recovery, limit injury and illness and helps to build confidence.  

Meeting High Energy Demands

The physical growth and development needs of adolescents, in addition to hectic school and sports training schedules, demands result a high energy demand for young athletes.

Macronutrient and energy targets are similar to those of adults, but the schedules create a challenge.  The fact that adolescents are going through a rapid period of growth and development combined with very hectic school and sports schedules (often training for multiple sports teams) can make meeting energy requirements very challenging.

Without adequate energy and carbohydrate intake, young athletes are under fuelling and face several risks:

• • Fatigue: Insufficient fuel can lead to reduced stamina and endurance.
  • Poor Performance: Under fuelling can directly affect athletic performance, making it difficult to train effectively and compete.
  • Difficulty Concentrating: Adequate nutrition is essential for maintaining focus and cognitive function both on and off the field.
  • Poor Growth/Development: Nutrition directly impacts physical growth, and inadequate intake can hinder normal development.
  • Delayed Puberty: Proper nutrition is integral to reaching developmental milestones on time.

Key nutritional recommendations

Carbohydrate. Many adolescents are very active and play multiple sports, so their energy requirements will be very high.  The higher the volume and intensity of physical activity, the more carbohydrates that are needed. After intense sport hunger will increase; adolescents should not ignore these hunger signals.  The body only stores a small amount of carbohydrate so these stores need to be topped up regularly throughout the day.  Potatoes, rice, pasta, bread, oats, cereal, fruits and vegetables are good sources of carbohydrate energy.  Choose high fibre options where available to get your gut healthy and prevent constipation.  Limit intake of processed sugary carbohydrates like cakes, sweets, jellies, ice cream and sports drinks.

Protein is required to carry out the following functions:

• • Growth – protein is needed during the growth spurt (in general, males will need higher amounts than females due to their larger muscle mass).
  • Repair and maintenance of body cells and tissues (as adolescents are a very active age group).
  • Energy – protein can be used as a secondary source of energy to meet the high demands during this stage of life.

Great sources of protein include lean red meat, soya, tofu, chicken, turkey, fish, eggs, nuts, yoghurt, milk, cheese and pulses.  Choose whole foods for protein intake rather than supplements at this age.

Fat is an important energy source and it also supports many organs including the brain.  Healthy fats are found in foods such as vegetable oils, oily fish (for example salmon, sardines, mackerel), nuts or avocados.  Foods containing less-healthy fats include crisps, pastries and fried foods – limit these as they can lead to becoming overweight.

Iron. Intense periods of growth during adolescence require more iron intake, in particular for girls who are losing blood through menstruation.  Iron rich foods include lean red meat, chicken, turkey, fish, eggs, pulses, dark green vegetables, or fortified cereals.  Vegetarians need to pay particular attention to iron levels. Vitamin C helps the body absorb iron from foods. Include fruits and vegetables rich in Vitamin C (citrus fruits, berries, peppers, broccoli) with meals.

Calcium. Growing adolescents need more calcium than adults as lifelong bone mass is developing during this time.  Calcium can prevent the incidence of osteoporosis in bones later in life.  It is recommended for adolescents to eat 3 or more portions of calcium-rich foods every day.  These include milk, cheese, yoghurt, fortified soya products, green leafy veg.

Calcium and vitamin D work together to increase calcium absorption.  Get vitamin D from sunshine, fortified foods or supplements.  Vitamin D also supports neuromuscular and muscle performance.

Hydration. It is important to drink plenty of fluids before, during and after playing sport.  Don’t wait until thirst kicks in because thirst is a sign that the body is already dehydrated and has needed fluids for a while.

See recipes idea’s for young athletes to obtain the nutrients they need for training.

In conclusion, fuelling fitness for young athletes extends beyond the training grounds; it begins at the dining table.  By understanding and implementing proper nutrition strategies, young athletes can unlock their full potential and achieve excellence in their sporting endeavours.

What is the Gut Microbiota and What Does It Do?

To understand how the gut microbiota affects sports performance, we need to know what it is and what it does.  Our intestine is home to a huge and diverse community of bacteria, viruses, and fungi.  These microorganisms are involved in many functions, such as breaking down food, synthesis important vitamins, influence good functioning of the immune system, and even talking to our brain, via what’s called the gut-brain axis.  The gut microbiome can change over time due to factors such as age, diet, lifestyle, medication, and stress.  A healthy gut microbiome is essential for our well-being and can protect us from infections, inflammation, and diseases².

Athletic Performance and Gut Microbiota: A Two-Way Relationship

Can the gut microbiota influence athletic performance such as how well we run, swim, or cycle?

Can exercise change the composition and function of our gut microbiota?  A recent study compared the microbiota of professional athletes to that of more sedentary individuals.  The results revealed significant differences between the two groups, both in terms of composition and functional metabolism¹.  Professional athletes exhibited greater bacterial diversity, with an increase in beneficial species, particularly those involved in the production of butyrate, a short-chain fatty acid crucial for gut health.   Butyrate is an extremely important type of short-chain fatty acid for maintaining gut health⁴.  It plays several beneficial roles, including strengthening our intestinal barrier, regulating inflammation, promoting nutrient absorption from our diet, contributing to the regulation of body weight, and even reducing the risk of certain gut diseases^{5, 6}.

Intense aerobic exercise appears to stimulate the growth of specific bacteria in our gut that produce this substance.  Additionally, a recent systematic review suggests that incorporating specific beneficial bacteria into the diet and using multi-strain probiotic supplements could potentially improve performance in various aspects, including endurance, strength, recovery, and physical conditions like muscle pain and body composition.  However, more research is required to establish conclusive causal evidence, as the current studies vary in their approaches and findings³.

On the other hand, some research has also suggested that excessive and prolonged exercise can cause temporary disruption of the microbiota, but these imbalances are generally reversible with adequate recovery time⁷.

The Gut Microbiota and Sedentary Individuals

Interestingly, these benefits also extend to sedentary individuals.  Although athletes often exhibit more pronounced alterations in their microbiota, studies indicate that regular physical exercise can also benefit the microbiota of sedentary individuals.  Incorporating a moderate exercise routine, such as a daily walk or strength training, can encourage greater microbial diversity within the gut, which could have beneficial effects on overall health.  Additionally, a balanced diet rich in fibre can also promote gut health.  Dietary fibres serve as food for the beneficial bacteria in the microbiota, thus promoting their growth and activity.  By incorporating foods such as fruits, vegetables, whole grains, and legumes into the diet, the necessary nutrients are provided for microbiota to thrive⁵. and reduce processed foods and those high in saturated fats⁷ which can have the opposite impact.

The interdependence between physical performance and the gut microbiota is becoming increasingly evident.  Regular physical exercise and a healthy diet can help promote microbial diversity, strengthening beneficial bacteria which can in turn enhance overall well-being.  Whether it be a professional athlete or someone living a more sedentary lifestyle, nourishing and nurturing the microbiota should be a top priority in terms of health and nutrition.

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?

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.

The World Health Organization recently undertook a novel food supply chain analysis to identify possible incentives and disincentives throughout the supply chain for sugar reduction. For sugar, the supply chain can include production of crop (sugar cane or beet), trade of raw or refined sugar, processing, adding the processed sugar to food or drink in manufacturing, and finally the sale of those foods or drinks.

The questions they attempted to find answers for are:

• What are the incentives and disincentives for industry to reduce the amount of sugar in manufactured food and drink products?
• At what point along the supply chain do these incentives and disincentives operate?
• Are there opportunities to effectively enhance the incentives and/or lessen the disincentives for reducing sugar?

The findings showed that there are areas where the supply chain supports sugar reduction, but also many barriers. There are many incentives to use sugar in foods and beverages, making it challenging to find alternatives or reduce total levels of sugar in products.

Source: World Health Organization Regional Office for Europe. Incentives and disincentives for reducing sugar in manufactured foods: an exploratory supply chain analysis. 2018.

These findings were used to create some preliminary insights from WHO on steps forward for reducing sugar, both at policy and manufacturer levels. These insights include:

• Disincentives for including added sugar in foods and beverages via policy (e.g. listing ‘added sugar’ to nutrition labels)
• Avoiding unintended consequences of sugar reduction – what is it replaced with? For example, if fat is added back, is the product higher in calories than the original higher-sugar version?
• Maintaining freshness and safety due to the functional role of sugar in foods and beverages

These considerations, as well as the rest outlined in the report, are critical when formulating sugar-reduced foods and designing policy to improve nutrition of the food supply.

Recently, taking ketones as a dietary supplement has been explored as a way to improve athletic performance. The idea behind this is to provide our muscles with an alternative, easily accessible fuel – especially for endurance training. Fat is a key energy source during endurance exercise, so think of it like a way to speed up our body’s ability to break down fat into energy.

A recent study in the Journal of Applied Physiology, Nutrition, and Metabolism explored the effectiveness of nutritional ketone salt supplements on exercise performance in healthy adult males. They found that the supplementation did improve fat oxidation, meaning that taking ketones improved energy availability for the athletes. However, time-trial power output was 7% lower in the athletes who took the ketones. In other words, ketones actually hindered the athletes’ ability to do high-intensity exercise.

The study findings mean that if you are a power athlete, like a sprinter, weight lifter, etc, ketones are not the supplement you should be looking for to improve performance. During any high-intensity exercise, where we need short bursts of power, our body relies on glucose. This explains why ketones had no benefit in the study here. If you do long, endurance-focused competitions, though, there may be a place for ketones to improve performance. Since ketone salts have substantial taste challenges (acetone is a ketone, as an example), incorporating them into foods or beverages may not be very welcome to typical consumers.