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Fact or Fiction: The vegan diet is unlikely to support optimal performance in athletes? 

Fiction! No evidence suggests a nutritionally balanced vegan diet impairs athletic performance (1,2). Google vegan athletes; you’ll find an impressive list of Olympians and elite athletes from many sports (football, basketball, tennis, rowing, etc.). That said, vegans (and vegetarians) could choose a diet that helps them be powerful athletes, but do they?

Some vegans eat too many salads, sweet potatoes & berries (or chips and candy), but not enough beans, nuts, and seeds. They eliminate animal protein but fail to replace it with enough plant protein. Weight-conscious vegan athletes who restrict calories often reduce their intake of protein and other nutrients. Hence, dieting vegan athletes need to be extra vigilant to consume a menu supportive of their needs.

Two keys to thriving on a balanced vegan (and vegetarian) sports diet are to consume:

1. adequate vitamins and minerals (in particular iron, zinc, calcium, iodine, vitamins D and B-12) as well as omega-3 fats, and
2. adequate protein from a variety of plant foods that offer a variety of amino acids (the building blocks of protein).

The amino acid leucine is of particular importance for athletes. Leucine is an essential amino acid your body cannot make, so you need to get it from food. Leucine triggers muscles to grow. It also can help prevent the deterioration of muscle with age. When you lift weights, you stimulate the muscles to take up leucine (and other amino acids); this triggers muscular growth. Hence, leucine is a very important component of an athlete’s diet!

The richest sources of leucine are animal foods, such as eggs, milk, fish, and meats. When a meat-eating athlete swaps beef for beans and other plant-proteins (hummus, quinoa, nuts, tofu, etc.), the swap commonly reduces leucine intake by about 50%. Hence, vegan athletes need to pay attention to getting enough high-quality plant-proteins that offer the optimal amount of leucine (about 2.5 grams per meal or snack). That means, vegans want to consistently enjoy soy, beans, legumes, seeds and/or nuts regularly at every meal and snack. Don’t have just oatmeal for breakfast; add soy milk and walnuts.  Don’t snack on just an apple; slather apple slices with peanut butter. Enjoy it with a swig of soy or pea milk instead of almond milk.

This table compares the leucine content of plant and animal foods. Note that when you swap animal-based protein for plant-based protein (such as trade eggs for peanut butter, or dairy milk for soy milk), you’ll likely need to eat more calories of plant-foods to get the same amount of leucine as in animal foods:

 How much protein and leucine do you need?

A 150-pound vegan athlete who seriously wants to build muscle should plan to eat about 20 grams of protein with 2.5 grams leucine every 3-4 hours during the day. (If you weigh more or less than 150 pounds, adjust that target accordingly.)  Here’s a sample 1,800-calorie vegan diet (read that, weight reduction diet for most athletes, both male and female) that offers adequate protein at every meal —but not always 2.5 grams leucine. To be a dieting vegan athlete requires some menu planning. Some dieters choose to be “mostly vegan.” This flexibility allows for leucine-rich milk, eggs & fish.

Note: I have not included fake meats such as the Impossible Burger or Beyond Burger in this menu. Those are ultra-processed foods that have a questionable place in any diet. I have also not included almond milk (a poor source of protein) nor supplements with leucine. You want to choose whole foods; they come with a matrix of nutrients that boost protein synthesis and can better invest in your health, recovery and overall well being.

Nancy Clark MS RD counsels both casual & competitive athletes at her Boston-area office (617-795-1875). The new 2019 edition of her best selling Nancy Clark’s Sports Nutrition Guidebook is available at www.NancyClarkRD.com, as is info about her popular online workshop.

For additional information about a vegan sports diet:

1) Wirnitzer, K. et al. 2018. Health Status of Female and Male Vegetarian and Vegan Endurance Runners Compared to Omnivores—Results from the NURMI Study (Step 2).  Nutrients 11(1):29  doi: 10.3390/nu11010029 (Free access)

2) Rogerson, D. 2017. Vegan diets: Practical advice for athletes and exercisers. J Int Soc Sports Nutr 14: 36  doi: 10.1186/s12970-017-0192-9 (Free access)