Do Vegetarian Diets Negatively Impact Sports Performance?

Do Vegetarian Diets Negatively Impact Sports Performance?

Adopting a healthy vegetarian diet, one that includes all the essential macro and micronutrients offers certain health benefits. Some research shows people that eat vegetarian diets have lower average body weights and reduced rates of heart disease, hypertension, type 2 diabetes and some types of cancer. Some studies also show that vegetarian diets may have longevity benefits.

Of course, not all vegetarian diets are the same. Lacto-Ovo vegetarians include milk and eggs in their diet along with plant-based sources of protein. Vegans avoid all products of animal origin including milk and eggs. Vegan diets may be significantly lower in calcium, vitamin D, vitamin B12 and zinc compared to a vegetarian diet that includes milk and eggs. Some vegan and vegetarian diets may be lower in iron and long-chain omega-3 fatty acids as well. Vitamin B12 is found naturally only in foods of animal origin, meat and dairy products, although some foods are fortified with B12. If not properly planned, a vegan diet may be low in protein as well.

But what if you’re an athlete? Athletes have slightly different nutritional needs compared to people who don’t expend much energy exercising. Athletes typically need more calories and higher levels of protein. Even people who do only endurance exercise and don’t strength train need higher levels of protein to help preserve muscle mass during endurance training. Therefore, you might think a vegetarian diet is a disadvantage if you’re an athlete. Is there any evidence of this?

Vegetarian Diets and Their Effects on Strength and Endurance

A 1994 study looked at vegetarian runners and omnivores that took part in a 1,000-kilometer race that lasted 20 days. Both groups consumed diets that were equivalent in terms of calories and macronutrients but one group got their calories and nutrients only from vegetarian foods. In this particular study, consuming a vegetarian diet had no impact on racing performance in this ultra-endurance race.

Another study looking at vegetarian kids in terms of body composition and fitness performance. In this study, vegetarian kids had better heart rate recovery after a step test than kids that were omnivores but they performed less well on fitness tests that measure strength and power like the standing long jump.

What about strength training? A study in older men showed men that consumed a vegetarian diet gained less muscle mass in response to resistance training than men eating an omnivorous diet.

Based on this limited research, it would appear that vegetarian diets might be beneficial for endurance sports but may not offer the same advantages for people trying to build strength, power or lean body mass.

One reason vegetarian, especially vegan diets, could limit performance with strength and power exercise is due to differences in muscle creatine phosphate levels. Creatine phosphate is the energy source your muscles use during high-intensity exercise of very short duration, a few seconds, a short sprint, jump, weight lifting etc. Vegetarians typically have lower creatine phosphate stores in their muscles compared to omnivores since creatine is found only in meat. In fact, research shows some vegetarians and vegans athletes may benefit from creatine supplementation.

Another issue in men and to a lesser degree in women is the effect vegetarian diets have on testosterone. Testosterone is an anabolic hormone that aids muscle development. Some studies show men that eat a vegetarian diet have lower testosterone levels than men that include meat and dairy in their diet. When you look at elite strength and power athletes, you don’t see a high proportion who eat a vegetarian diet, but it’s possible that the type of people drawn to this type of sport is a person more likely to eat meat.

The Bottom Line?

Vegetarian and vegan diets may have differing effects on athletic performance depending upon the type of exercise performed. There seems to be little downside to consuming a nutritionally-balanced vegetarian diet if you’re a long-distance runner or cyclist. In fact, it may offer benefits. Vegetarian diets are higher in carbohydrates that boost muscle glycogen for greater endurance. Still, vegetarian endurance athletes still need to consume adequate amounts of plant-based protein and need more than people who are sedentary.

Whether a vegetarian diet hurts performance in strength and power exercise is less clear. If there is a disadvantage, creatine supplementation along with an increase in plant-based protein may help vegetarian and vegan athletes compensate for the lack of animal protein.

If you’re trying to build lean body mass or strength and you’re eating a vegetarian diet, make sure you’re getting enough plant-based protein from a variety of sources including fermented soy, whole grains, beans, and lentils. If you’re not vegan, eggs are the highest quality source of protein to help promote muscle growth.

There’s some evidence that the amino acids in plant-based proteins may be less easily absorbed and utilized compared to animal-based protein, partly because fiber reduces their absorption. If you eat mostly plant-based protein, you may need to increase your protein intake slightly to compensate.

If you’re eating a vegan diet, you’re at greater risk for deficiencies in zinc, calcium, vitamin B12 and vitamin D. All vegans should take a B12 supplement. Calcium supplements are controversial after a study showed a link between calcium supplements and a greater risk for heart disease. If you’re vegan, some forms of tofu are high in calcium. Read the label. Be sure to eat lots of green, leafy vegetables, another good non-dairy source of calcium.

Eating a vegetarian diet has health benefits if you plan it properly. Whether it has the same benefits for strength and power athletes is unclear. At the very least, vegetarian strength and power athletes should eat a diet higher in plant-based protein from a variety of sources and ensure they’re getting enough calcium, zinc, vitamin B12, iron, and vitamin D.



Sportsci.org. “Effects of Vegetarian Diets on Performance in Strength Sports”

Am J Clin Nutr May 2009 vol. 89 no. 5 1627S-1633S

Brown University Education. “Being a Vegetarian”

Medscape Family Medicine. “Health Benefits of a Vegetarian Diet”

Today’s Dietitian. Vol. 11 No. 1 P. 38. (2009)


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