Vegetarian Diet for Athletes – A Few Considerations (Part I)
In a two part special, guest blogger Richard Chessor, the lead nutritionist for Scottish Rugby, discusses the implications and considerations of vegetarian diets as a way to improve athletic training and performance.
PART 1: THE PRIMARY CONSIDERATIONS
Note – this article refers to vegetarians as lacto-ovo-vegetarians (those that eat dairy and eggs but avoid eating meat, fish and poultry) as this is the most commonly adopted vegetarian diet in UK.
Vegetarian diets are commonplace in Western society and the reasons for selecting a vegetarian diet are numerous and diverse. Many athletes adopt a vegetarian diet not for ethical or religious reasons but in an attempt to maximize their athletic performance. This two-part blog begins by highlighting some of the primary nutritional considerations for the vegetarian athlete before Part 2 delves into some of the more often overlooked ‘pitfalls’ of athletic vegetarianism.
There are few estimates of the prevalence of vegetarian diets in athletes, but it would appear to be more popular in endurance athletes (cyclists, runners and triathletes) who require a consistently high carbohydrate intake whilst maintaining a low body weight to support optimal training. The popularity of vegetarianism in strength trained athletes appears lower perhaps due to the higher requirement for protein (or increased diversity of protein sources) required to maintain an elevated muscle mass. Whilst in the general population a vegetarian diet is associated with a decreased morbidity from chronic lifestyle diseases (although lifestyle factors independent of diet may partially explain this) this is often not the primary concern for the athlete considering vegetarianism. Of greater relevance to the athlete is to query if their nutrient needs can be met and performance maintained or improved by adopting a vegetarian diet.
The primary nutritional challenges to the vegetarian athlete are to meet their demands for energy, protein, iron, zinc, calcium and omega-3 fatty acids.
ENERGY – The energy demands to support training and competition performance can often be difficult to achieve through a vegetarian diet for two main reasons. Firstly, vegetarian diets tend to be higher in fibre and bulk which provides a greater satiety effect thus reducing overall food intake. Whole grains, legumes, nuts, seeds, fruit and vegetables all provide a significant fibre source to the diet and are staples for most vegetarians. Secondly, the absence of animal meats removes a sizeable proportion of fat from the diet which may not be fully replaced with plant based sources such as vegetable oils, avocado, nuts and seeds thus making the vegetarian diet a lower fat diet than their omnivorous counterpart. Carbohydrate tends to have a greater overall contribution to energy needs and therefore the vegetarian athlete may place greater reliance on high carbohydrate food sources to achieve their energy targets and inadvertently create macronutrient imbalances in their diet or compromise the quality of their food intake.
So, is energy an issue? Not necessarily, but the vegetarian athlete must be aware of their individual energy needs and should be able to react to the varying energy needs of training and competition without compromising the quality of their food intake.
PROTEIN – Protein recommendations for athletes are greater than that of the general population however vegetarian diets consistently report lower protein intakes than meat eaters. This creates a significant challenge for the vegetarian athlete to consume a sufficient amount of protein to support optimal performance, recovery and adaptation. Further to this, few vegetarian sources of protein provide the full range of amino acids necessary for optimal muscle function and therefore potentially leave the vegetarian athlete at risk of compromised performance. When foods are limited in one or more essential amino acids, a variety of protein sources should be consumed to ensure the correct balance of amino acids is achieved. Of particular concern is the amino acid leucine which plays a critical role in orchestrating the production of new muscle proteins. Leucine is abundant in animal sources of protein and thus the vegetarian athlete may need to pay greater attention to their intake of eggs and dairy products to meet their leucine needs.
So, is protein an issue? Yes, not only must the vegetarian athlete pay close attention to their total protein intake they must also carefully consider the composition of their protein intake which requires increased knowledge, planning and preparation.
IRON – Iron plays an essential role in the transport of oxygen within our body. Athletes (especially endurance athletes) are at greater risk of depleting iron stores and if untreated this can develop into anaemia which severely affects exercise performance and overall health. Iron is primarily consumed through meat, seafood and poultry and naturally vegetarians report lower iron levels than omnivorous eaters. Although iron is present in plant-based foods such as grains, legumes, vegetables and fruits its bioavailability (the amount of iron that your body can actually extract) is much lower than that of animal-based iron. Furthermore, iron absorption can be enhanced or inhibited by other nutrients in our diet. Vitamin C and some fermented foods greatly improve our absorption of iron whereas phytates from grains, peanuts, soy and polyphenols from strong tea and coffee can inhibit iron absorption. Therefore, the challenge for the vegetarian athlete (as with their protein consumption) is not only to consume enough iron but to maximise their iron absorption by careful integration of iron-rich foods alongside iron absorption enhancing foods whilst minimising iron inhibiting foods.
So, is iron an issue? Yes, significant consideration should be put into the iron intake of a vegetarian athlete (especially endurance athlete) to prevent depletion in iron stores without compromising the intake of other key nutrients.
ZINC – Zinc is essential for immune function and in the regulation of many enzymes in the body. Zinc requirements are higher for athletes than the general population due to increased zinc losses through sweat. Similar to iron, it is abundant in the vegetarian diet but is not readily absorbed from plant foods. Beans, whole grains, nuts and seeds all contain high sources of zinc but are also high in phytates which inhibit the absorption of both iron and zinc. So despite good zinc sources in a vegetarian diet the low absorption efficiency may result in a deficiency for the vegetarian athlete which could compromise immune function, training adaptation and testosterone production.
So, is zinc an issue? Yes, as with iron, careful planning is required to meet zinc requirements without compromising the intake of other nutrients.
CALCIUM – Calcium is essential for optimal bone formation and muscle function. Vegetarians who consume dairy products are often not at risk of sub-optimal calcium intake (especially if an increase in dairy foods is being used to support protein intake). However, calcium deficiency is a key consideration for vegan athletes as few foods apart from dairy products provide a concentrated source of calcium.
So, is calcium an issue? It’s unlikely to be an issue for athletes unless dairy products are avoided. However, calcium fortified foods may be necessary for vegans or those who avoid dairy.
OMEGA-3 ESSENTIAL FATTY ACIDS – The Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential fatty acids which positively contribute to heart and brain health but they also play important roles in the modulation of the post-exercise inflammatory response. Most commonly found in cold water oily fish they are almost completely absent in the vegetarian diet. However, alpha-linolenic acid (ALA) is another omega-3 fatty acid which can elongate to produce EPA & DHA in the body and is commonly found in flaxseed, walnuts and pumpkin seeds. The conversion of ALA to EPA & DHA is not particularly efficient therefore to avoid a deficiency of EPA & DHA a high intake of ALA-rich foods is required.
So, are omega-3 fatty acids an issue? Yes, although these key fatty acids can be produced from vegetarian foundations this is an inefficient process and as we will see in Part 2 consuming the appropriate balance of omega-3 fats is a crucial consideration for athletes.
So, can a vegetarian diet be appropriate for an athlete? Yes, with suitable knowledge, planning and a diverse food intake it is certainly possible for an athlete to meet their primary nutrition goals through a vegetarian diet. It may be easier for the endurance athlete than the strength training athlete due to the natural tendency for vegetarian diets to be higher in carbohydrate and lower in protein. In comparison to the omnivorous athlete the vegetarian should have greater knowledge of their nutrient requirements, their practical application and the various food interactions that positively and negatively contribute to nutrient absorption which may impact exercise performance.
However, although it may be possible for primary nutrient needs to be met through a vegetarian diet this does not necessarily mean that vegetarian diet is the optimal diet for athletic performance.
In Part 2 we will explore some of the more often overlooked aspects of the vegetarian diet and reflect on their relevance to athletic performance.
Look out for Part 2 of this blog next month, subscribe to our newsletter for updates.