What Are Nutritional Considerations for Athletes Who Use Plants as Fuel?
More and more athletes competing in endurance events are deciding to switch to a vegetarian or even, in some cases, vegan diet. Is this a good idea? Can this change in eating habits improve performance? Should we be concerned about the risk of nutritional deficiencies or inadequate nutritional intake over the long term? Regardless of the situation, proper nutrition planning will certainly help maintain optimal health and sustain performance.
First of all, it is important to be aware that there are different levels of vegetarianism. Some choose to keep eggs, fish and dairy products in their diet, while others choose a completely vegan diet, i.e., one that excludes all animal products.
It is certainly possible to have a healthy, balanced and performance-oriented diet with a vegan diet. However, there are some factors that must be considered to ensure that all of the specific nutritional needs of endurance athletes are adequately met. Here is a brief overview on the subject.
An athlete's requirements for protein varies according to his or her goals and training volume. An adequate supply of protein ensures, among other things, an optimal adaptation process as a response to training, in addition to providing a sense of satiety during meals. There is evidence that vegan athletes tend to consume less protein than their vegetarian or omnivorous counterparts (1). Optimizing protein intake is thus an important thing to keep in mind. Furthermore, proteins from plants generally contain fewer branched-chain amino acids, especially leucine. In particular, leucine is a major driver of muscle protein synthesis and also plays an important role in various adaptations and the recovery processes following physical exertion (2, 3). In order to obtain an adequate protein intake, it is important to vary your food sources and to include foods that are rich in high-quality vegetable proteins in every meal. The following table is an overview of the protein content of some plant-based foods. In some situations, a leucine-enriched vegetable protein supplement can be a valuable addition to post-training recovery.
Essential Fatty Acids
Due to the absence of food from the sea such as fatty fish, the intake of EPA and DHA omega-3 fatty acids in vegans should be monitored. Omega-3s play an important role in cardiovascular health in addition to having an anti-inflammatory effect in the body. The positive effect of omega-3s on performance is still the subject of debate and research, but may be beneficial (4). The regular consumption of flaxseed and chia, walnuts and canola oil is one way to integrate omega-3 from plant sources, however these foods do not provide the EPA and DHA type omega-3s that would be more beneficial, particularly in terms of inflammation control. A microalgae oil-based supplement may therefore be an option for individuals who do not consume fish.
Obtaining a sufficient intake of micronutrients such as vitamins and minerals is also important for athletes. Although plant-based foods are an important source of micronutrients, some are predominantly found in animal products. By eliminating these foods, special attention should therefore be devoted to choosing plant sources that will be able to compensate for this deficit (5).
Vitamin B12 intake is of particular concern since plant-based foods do not naturally contain vitamin B12. Some products such as vegan beverages (soy, almond, rice, etc.) are fortified with vitamin B12, as well as products sold as meat alternatives. Regularly adding these foods to the menu can help prevent deficiencies.
Certain minerals such as iron, zinc and calcium should also be monitored. Poor bioavailability of iron in the vegan diet makes it a nutrient at high risk of deficiency among endurance athletes, especially women who have higher requirements. Vegetarians and vegans tend to consume roughly the same amounts of iron in their diets. However, some nutritional factors such as phytates found in whole grains and legumes tend to be more prevalent in the vegan diet and may further reduce iron absorption.
In general, zinc is usually abundant in plant-based foods, but like iron, its bioavailability is not as good as that of animal-based foods. In order to achieve sufficient intakes, regular consumption of hemp, sunflower seeds, nuts, whole grains and legumes is recommended. Also, processing methods such as soaking or fermentation improve the absorption of zinc from food.
Lastly, with regard to calcium, it is widely found in certain green vegetables such as broccoli, bok choy and kale. Fortified plant-based beverages as well as tofu prepared with calcium sulfate are interesting sources and should be regularly on the menu to avoid deficiencies. Sufficient vitamin D intake also promotes better absorption of calcium from food. During the winter months, vitamin D supplements may be necessary since exposure to sunlight may be insufficient to ensure synthesis through the skin. Several vitamin D supplements are made from sheep's wool. If you follow a strict vegan diet, be sure to choose a lichen-based supplement.
What about performance?
How does a vegetarian or vegan diet affect physical performance? At this time, there are no studies to prove that a vegetarian diet can have any beneficial effect on physical performance. However, it has been proven that a properly balanced vegetarian or vegan diet can maintain a level of performance equivalent to that of a good quality omnivorous diet. So, a vegetarian diet will not improve your performance, nor will it diminish it (6).
The decision to adopt a vegetarian or vegan diet should first and foremost be a personal choice, motivated primarily by ethical, environmental or health beliefs. Performance will depend on your training and the overall quality of your diet, regardless of whether it is omnivorous or vegan. The important thing continues to be providing adequate energy and micronutrient intakes, while planning carbohydrate and protein intakes to match the training load and desired physiological adaptations.... And this is entirely possible, regardless of your food model.
- Venderley A, Campbell W. Vegetarian Diets: Nutritional Considerations for Athletes. Sports Med. 2006;36(4):293–305.
- Tipton KD, Wolfe RR. Protein and amino acids for athletes. J Sports Sci. 2004;22(1):65–79.
- Campbell B et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2007;4-8.
- Mickleborough, TD. Omega-3 Polyunsaturated Fatty Acids in Physical Performance Optimization. Int J Sport Nut Exerc Metab. 2013, 23, 83-96
- Rogerson, D. Vegan diets: practical advice for athletes and exercisers. J Int Soc Sport Nutr. 2017. 14-36
- Craddock, JC. Et al. Vegetarian and Omnivorous Nutrition—Comparing Physical Performance. Int J Sport Nutr Exerc Metab. 2016, 26, 212-220