Dispelling Protein Myths

Dispelling Protein Myths

By Chris Rosenbloom, PhD, RDN  | Wednesday, February 21, 2018

Swimmers often ask about protein, and while protein is a hot topic in sports nutrition for good reason, some lingering myths remain. This is especially true for vegetarian athletes who know they need protein but don’t eat the usual sources of eggs, milk, meat or seafood. Here are the top concerns I hear from vegetarian swimmers and some facts to set the record straight.


True or False? Vegetarian athletes need more protein than their non-vegetarian friends.

False: All athletes have higher protein needs than those who don’t exercise, but vegetarians have the same need for protein as other athletes. If you are eating enough calories and getting protein from a variety of foods (beans, nuts, seeds, grains, soy, rice and pasta) you will get good quality protein to support training.


True or False? Soy foods contain substances that act like estrogen and lead to hormonal imbalances, so they aren’t healthy for either male or female athletes.

False: This myth has been around for a long time, so time to squash it. Soy contains a type of plant nutrient called isoflavones that has a similar structure to estrogen but doesn’t bind to the estrogen receptors on our cells in the same way human estrogen does. The isoflavones in soy don’t increase breast cancer risk in women, and for those who have had breast cancer, both the American Cancer Society and American Institute for Cancer Research (AICR) say soy foods (or soy isolates found in protein powder or added as ingredient to energy bars) are safe. The AICR lists soy as food that fights cancer.

And, as for the myth that soy is feminizing for men, research shows that soy does not increase circulating estrogen or decrease testosterone levels, so no need to shun soy.


True or False: Leucine, the amino acid that exhibits the greatest effect in turning on muscle protein synthesis is only found in whey protein found in dairy foods.

False: While it is true that leucine is called the “anabolic trigger” and researchers suggest athletes get leucine-rich protein foods in the hours after exercise, whey protein isn’t the only leucine-rich food. Here’s a handy chart showing protein and leucine content of plant foods, compared to a cup of milk:

1 cup nonfat milk   8.3 grams protein   0.8 grams leucine 
½ cup firm tofu  20 grams protein  1.5 grams leucine
½ cup soft tofu     8 grams protein   0.6 grams leucine
½ cup black beans  7.6 grams protein   0.6 grams leucine
½ cup lentils    
 9 grams protein  0.65 grams leucine 


Vegetarian athletes can get high-quality protein from plants and sufficient leucine to stimulate muscle protein synthesis. Try blending tofu in a smoothie, adding to soup, or a noodle bowl for an easy way to get leucine-rich protein.


True or False
: There is no upper limit to how much protein an athlete should eat.

False: Too much of a good thing is too much. Swimmers need carbohydrate, protein, and fat to perform at their best. Displacing carbohydrate and fat by only eating protein will not help your performance or your health.

Information for this post came from a variety of sources, including a talk at a sponsored conference from Michelle Braun, of the Global Protein Scientific Affairs office of DuPont Nutrition and Health, the website of the American Institute for Cancer Research, and the chapter on vegetarian athletes in the 6th edition of Sports Nutrition: A Handbook for Professionals. I was not asked to write this article, nor did I receive any compensation from DuPont or the AICR.

Chris Rosenbloom is a registered dietitian nutritionist and professor emerita of nutrition at Georgia State University. She welcomes questions from swimmers, parents and coaches. Email her at chrisrosenbloom@gmail.com; follow her on Twitter @chrisrosenbloom.



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