THE VEGETARIAN ATHLETE: NUTRITIONAL CONSIDERATIONS

Article Published in the Portuguese Journal of Sports Medicine

Dr. Ana Goios^1,2Dr. Rogério Pereira^3-6Dr. Ana Isabel Monteiro⁷Dr. Márcia Gonçalves¹Prof. Dr. João Espregueira-Mendes^3,4,8-10

¹Faculty of Nutrition and Food Sciences, University of Porto; ²Institute of Public Health of the University of Porto; ³Clínica do Dragão, Espregueira-Mendes Sports Centre - FIFA Medical Centre of Excellence, Porto; ⁴Dom Henrique Research Center, Porto; ⁵Faculty of Sports of the University of Porto; ⁶School of Health, Fernando Pessoa University, Porto; ⁷Youth Department of the Vila Nova de Famalicão City Hall; ⁸Futebol Clube do Porto; ⁹ICVS/3B's-PT Government Associate Laboratory, Braga-Guimarães; ¹⁰3B's Research Group, Guimarães; ¹¹School of Medicine, University of Minho, Braga, Portugal.

RESUMO / ABSTRACT

Given the increasing interest and adherence of athletes to a vegetarian diet, it is necessary to reflect and investigate the nutritional adequacy and potential effect on health and sports performance. A well-planned vegetarian diet that includes a wide variety of plant-based foods can meet the energy and nutritional needs of any athlete. Special attention should be given to protein, omega-3 fatty acids, calcium, iron, iodine, zinc, and vitamins B12 and D, and supplementation may be necessary. There is no evidence for a positive or negative impact of this dietary pattern on sports performance.

Given the increased interest and adherence to a vegetarian diet by athletes, it is relevant to reflect and research about their nutritional adequacy and potential effect on health and athletic performance. Appropriately planned vegetarian diet, including a wide variety of plant-based foods, can provide sufficient energy and nutrients to meet athletes' needs. Special attention should be paid to the intake of protein, omega 3 fatty acids, calcium, iron, iodine, zinc and vitamins B12 and D, being the supplementation eventually needed. Convincing evidence in support of beneficial or adverse effects on performance of vegetarian diets is not available.

PALAVRAS-CHAVE / KEYWORDS

Dieta vegetariana, dieta vegan, atletas, saúde, performance

Vegetarian diet, vegan diet, athletes, health, performance

Background:

The scientific evidence in favor of a greater presence of plant-based foods has increased, particularly in terms of reducing the risk of chronic diseases such as cardiovascular disease, certain types of cancer, type II diabetes, and obesity.¹ Social media has contributed to increase the visibility and dissemination of the vegetarian diet. Besides the alleged beneficial effects related to health, there are several reasons that may lead to the adoption of this type of eating pattern, from environmental, ethical, religious and cultural issues to animal welfare.² In sports, the testimony of successful athletes worldwide, such as Novak Djokovic, Lewis Hamilton, and Venus Williams, has been fostering interest and promoting the adoption of this dietary pattern as a way to optimize sports performance. But are vegetarian athletes capable of meeting their energy and nutritional needs?

Nowadays, it is known that a vegetarian diet, if well planned, is capable of meeting the energy and nutritional needs of any human being, and can be adapted to all stages of the life cycle and conditions (including pregnant women, infants, children, adolescents, and the elderly) and to athletes.³  However, "vegetarian diet" is a generic term given to a set of eating patterns, in which products of plant origin predominate, but with considerable nutritional differences depending on the food group(s) excluded [Table 1]. ²

Table 1. Vegetarian Diet: Classification.

Nutritional considerations

Ensuring an adequate energy and nutritional intake for the level of physical activity should be a priority for all athletes, whether vegetarians or omnivores.⁴

A balanced plant-based diet stands out for its richness in micronutrients (potassium, magnesium, folate, vitamins A, C, E, and K), antioxidants, polyphenols, and for the high presence of carbohydrate-supplying foods (namely cereals, legumes, and fruit), characteristics that make it interesting in terms of sports performance and recovery.^{5, 6} Nevertheless, a poorly constructed plant-based diet may compromise the intake of some nutrients critical for health and sports performance. Depending on the dietary pattern, food preferences/choices, and intensity of physical exercise, some vegetarian athletes may have difficulty meeting energy needs and their diet may have sub-optimal amounts of protein, omega-3 fatty acids, some vitamins (D and B12) and minerals (iron, calcium, iodine, and zinc), which is due to the lower amount and/or lower bioavailability of these nutrients in plant-based foods. ^5-7

Energy

Energy needs vary greatly between athletes. Besides factors inherent to the athlete himself, such as gender, age and body composition, other variables of the exercise practiced such as duration, intensity and periodization of training (which can vary from day to day and with the phase of the sports season) are determinant. Meeting energy needs may be a challenge for some vegetarian athletes due to the low energy density and high fiber content that characterize foods that are part of a plant-based diet.⁸ These athletes should be encouraged to have several meals/snacks throughout the day (~5-8/day), to select foods that are high in energy density (e.g. oleaginous fruits) and low in fiber (e.g. more refined cereals, fruit juices, etc.), and to properly organize their eating day so that food is always readily available.^{8, 9}

Protein: quantity and quality

It is generally agreed that athletes have higher protein needs (1.4 to 2.0 g/kg/day) than the general population (0.8 g/kg/day).¹⁰ Despite insufficient scientific evidence to suggest different recommendations for vegetarian athletes compared to omnivorous athletes, some authors consider it prudent for vegan athletes to "steer" their protein intake towards the upper limit of the recommendations (~2.0 g/Kg/day or up to 2.7 g/Kg/day during periods of greater energy restriction) to compensate for the lower biological value of plant-based proteins.¹¹

The quality of a protein can be defined as its ability to stimulate muscle protein synthesis, and is determined by two parameters: the content of essential amino acids and digestibility. Compared to proteins of animal origin, proteins of plant origin contain lower essential amino acid content (particularly leucine, an amino acid with a widely recognized role in stimulating protein synthesis via activation of mTOR) and lower digestibility.¹⁰ However, it is known that a vegetarian diet, which includes the consumption of a wide variety of foods rich in plant-based protein during the day, is capable of providing all the essential amino acids to support the training program and promote recovery.⁵

The anabolic potential appears to be higher in proteins of animal origin. However, the existing studies are limited, focusing mostly on soy, wheat and rice protein, and therefore, more studies are needed that look at the anabolic properties of other plant sources.¹² Additionally, some authors suggest that as long as the daily protein intake is sufficient and capable of providing the amount of essential amino acids (particularly leucine) needed to stimulate protein synthesis, the difference between protein sources (animal origin versus vegetal).¹³

Ergogenic Supplements

As in the omnivorous athlete, the use of ergogenic supplements should be properly considered and contextualized. In vegetarian athletes, creatine and beta-alanine supplementation has some particularities.

Creatine

Creatine is formed from three amino acids (methionine, glycine, and arginine) found primarily in meat and fish. Vegetarian diets have been associated with a reduction in muscle creatine stores.^{16, 17} In an 8-week study, Burke et al. reported positive effects on performance and body composition in vegetarian athletes, suggesting that creatine supplementation may be even more beneficial in athletes with reduced baseline creatine levels compared to omnivorous athletes.¹⁸

Beta-alanine

Beta-alanine is a precursor amino acid in the synthesis of carnosine, a recognized intracellular buffering agent, and can be obtained from the regular consumption of meat and fish. Vegetarian athletes have reduced levels of carnosine at the muscle level.^{19, 20} However, studies are needed to prove a possible superior ergogenic effect in vegetarian athletes.¹¹

Impact on performance

Despite the alleged beneficial effects on the athlete's health, there is not enough scientific evidence to suggest that a vegetarian diet per se is higher or lower than an omnivorous diet in terms of performance and sports performance. However, further studies involving competitive athletes and with longer follow-up (>6 months) are needed.^{8, 21, 22}

Conclusion:

Any athlete, whether omnivorous or vegetarian, who wishes to optimize health and sports performance should follow a well-planned, properly supplemented, varied and balanced diet. The vegetarian athlete should pay special attention to the intake of protein, omega-3 fatty acids, calcium, iron, iodine, zinc, and vitamins B12 and D. A vegetarian diet per se does not seem to influence sports performance in a positive or negative way.

Bibliographic references:

1. Dinu M, Abbate R, Gensini GF, et al. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2017;57(17):3640-9.
2. Silva S, Pinho J, Borges C, et al. Guidelines for Healthy Vegetarian Food. Lisbon 2015.
3. Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116(12):1970-80.
4. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016;48(3):543-68.
5. Fuhrman J, Ferreri DM. Fueling the vegetarian (vegan) athlete. Curr Sports Med Rep. 2010;9(4):233-41.
6. Venderley AM, Campbell WW. Vegetarian diets : nutritional considerations for athletes. Sports Med. 2006;36(4):293-305.
7. Barr SI, Rideout CA. Nutritional considerations for vegetarian athletes. Nutrition. 2004;20(7-8):696-703.
8. Larson-Meyer DE. Vegetarian and Vegan Diets for Athletic Training and Performance. Sports Science Exchange. 2018;29(188):1-7.
9. Larson-Meyer DE. Optimizing Performance on a Vegetarian Diet. In: Craig WJ, editor. Vegetarian Nutrition and Wellness. New York: CRC Press; 2018. p. 303-19.
10. Jager R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
11. Rogerson D. Vegan diets: practical advice for athletes and exercisers. J Int Soc Sports Nutr. 2017;14:36.
12. van Vliet S, Burd NA, van Loon LJ. The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr. 2015;145(9):1981-91.
13. Gorissen SHM, Witard OC. Characterising the muscle anabolic potential of dairy, meat and plant-based protein sources in older adults. Proc Nutr Soc. 2018;77(1):20-31.
14. Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15(1):38.
15. (EFSA) EFSA. Dietary Reference Values for nutrients. Summary Report. EFSA supporting publication 2017:e15121. 2017.
16. Harris RC, Soderlund K, Hultman E. Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin Sci (Lond). 1992;83(3):367-74.
17. Lukaszuk JM, Robertson RJ, Arch JE, et al. Effect of creatine supplementation and a lacto-ovo-vegetarian diet on muscle creatine concentration. Int J Sport Nutr Exerc Metab. 2002;12(3):336-48.
18. Burke DG, Chilibeck PD, Parise G, et al. Effect of creatine and weight training on muscle creatine and performance in vegetarians. Med Sci Sports Exerc. 2003;35(11):1946-55.
19. Everaert I, Mooyaart A, Baguet A, et al. Vegetarianism, female gender and increasing age, but not CNDP1 genotype, are associated with reduced muscle carnosine levels in humans. Amino Acids. 2011;40(4):1221-9.
20. Harris RC, Wise JA, Price KA, et al. Determinants of muscle carnosine content. Amino Acids. 2012;43(1):5-12.
21. Craddock JC, Probst YC, Peoples GE. Vegetarian and Omnivorous Nutrition - Comparing Physical Performance. Int J Sport Nutr Exerc Metab. 2016;26(3):212-20.
22. Lynch H, Johnston C, Wharton C. Plant-Based Diets: Considerations for Environmental Impact, Protein Quality, and Exercise Performance. Nutrients. 2018;10(12).

FIVE RECIPES CALCULATED FOR VEGETARIAN ATHLETES

The diet of vegetarian athletes should include a wide variety of foods to provide all the nutrients necessary for optimal health and sports performance.

The following five recipes are nutritionally adequate, tasty, and easy to prepare, and are recommended for inclusion in the diet plan of vegetarian/vegan athletes.

The estimated nutritional information per serving is presented in Table 1. The portions are merely suggestive, so they should be adjusted to your needs, energy/nutritional requirements and the objective of each athlete.

Breakfast:  

Recipe 1. Oatmeal in the oven [8 servings]

Ingredients:

• 2 cups of fine oat flakes;
• 1 cup of coarse whole grain oat flakes;
• 2 tablespoons of ground flaxseed;
• 2 cups unsweetened soy beverage;
• 1 tablespoon agave syrup (or other sweetener);
• 2 teaspoons of vanilla essence;
• 1 ripe banana;
• 1 cup of red berries;

Preparation:

• Mash the banana with the soy drink, agave syrup, and vanilla essence; add the flaxseed and stir well;
• In a tureen or pyrex (greased with a little olive oil), place the oat flakes and then pour the previous mixture, distributing evenly;
• Add the red fruits and bake at 180 °C for 30 minutes.

Suggestion: serve with vegetable yogurt

Morning/afternoon snack:

2. Energy bars [8 servings]

Ingredients:

• 1 cup of coarse whole grain oat flakes;
• 1 cup of puffed cereal;
• ¼ cup peanut butter;
• ¼ cup of date syrup;
• ¼ cup of pecans;

Preparation:

• Mix all the ingredients together;
• Pour onto a tray lined with baking paper and spread evenly, kneading;
• Divide into 8 portions (it is easier to do this step before baking) and bake for 15 minutes at 180 °C (with ventilation).

Suggestion to increase the protein content of the meal: accompany with a vegetable protein shake

Pre-workout snack:

3. Coffee Pancakes [3 servings]

Ingredients:

• 1 cup spelt flour (or other);
• 3 tablespoons of coconut flour;
• 2 tablespoons of carob flour or cocoa;
• 1 tablespoon coconut sugar;
• 1 tablespoon of baking powder;
• 200mL of soy beverage (no sugar added);
• 1 espresso coffee;

Preparation:

• Mix the dry ingredients in a large bowl; add the wet ones and mix well;
• Heat a non-stick frying pan or plate, brush with a little olive oil, and place two tablespoons of batter per pancake. When bubbles form on the surface, flip with a spatula and cook for a few more seconds; move to a cooling rack and repeat the process.

Suggestion: serve with oleaginous fruit butter and/or fruit (in the photo: caramelized banana)

Lunch or dinner:

4. Lentil and pumpkin stew [2 servings]

Ingredients:

• ½ tablespoon of olive oil;
• 1 onion;
• 2 cloves of garlic;
• 2 ripe tomatoes (or ½ can of crushed tomatoes);
• < ¼ teaspoon chili;
• ¼ teaspoon cumin;
• 1 teaspoon of paprika;
• 1 bay leaf;
• 100g mushrooms, cut into strips or quarters;
• ¼ butternut squash, diced;
• ½ cup (100g) brown/green lentils;
• 1 cup of water;
• Fresh parsley, chopped; salt and black pepper to taste;

Preparation:

• In a medium nonstick pan, sauté the chopped onion and garlic in olive oil for 3-4 minutes;
• Add the ripe tomatoes and spices, and let it cook; as soon as the tomatoes are reduced to a sauce, add the mushrooms and pumpkin and let it simmer for 5-7 minutes over medium heat;
• Add the lentils and water, reduce the heat and cover the pot; simmer for about 10 minutes and, season with a pinch of salt and black pepper; cook for another 3-5 minutes until the lentils are soft;
• Add the fresh herbs and stir.

Suggestion: serve with bread or rice

5. Chickpea and bell pepper balls [3 servings]

Ingredients:

• 1 can (260 g) cooked chickpeas, well drained;
• 2 teaspoons of olive oil;
• 1 onion;
• 2 cloves garlic, sliced;
• 1 elongated tomato, diced;
• ¼ red bell pepper, diced;
• 40 g thin texturized soybeans;
• 2 teaspoons of paprika;
• ½ teaspoon dried oregano;
• ½ teaspoon dried basil;
• ¼ teaspoon chili powder;
• 2 tablespoons fresh parsley or coriander, chopped;
• Black pepper to taste;

Preparation:

• In a skillet, heat 1 teaspoon of olive oil, and sauté the onion, garlic, tomatoes, and peppers for 8-10 minutes, until the onion is translucent, and the vegetables are tender;
• Add the chickpeas and crush with a spoon until coarsely crumbled;
• Add the soy, and 1 to 2 tablespoons of water, if necessary, to bind the preparation together;
• Add the spices and adjust the seasoning;

If necessary, adjust the consistency by adding water if the mixture is too dry, or flour/flakes/seeds or ground fatty fruits if the preparation is too dry;

• Form 12 to 16 balls;
• In a non-stick pan, heat the remaining teaspoon of olive oil and pass a napkin to coat the entire surface of the pan; place the balls and cook for 3 minutes, stirring the pan frequently.

Suggestion: serve with pasta or rice and vegetables to taste

Table 1. Nutrition information estimated by portion.

Sources: USDA Food Composition Database; Food Composition Table of the National Institute of Health Doutor Ricardo Jorge; nutritional information consulted on labels;

Goios A, Liz Martins M, Oliveira AC, Afonso, C, Amaral T (2016). Food Weights and Portions. U. Porto Edições. 2ªEd.

Goios A., Pereira R., Monteiro A. I., Gonçalves M., Espregueira-Mendes J. (2020). The Vegetarian Athlete: Nutritional Considerations Med Desp Informa Journal, 11(2):28-30. DOI: 10.23911/clinica_dragao_2020_3.

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