By Stephanie Boville MsC, RD
Benefits of a vegan diet for athletes
While vegetarian and vegan diets have become more popular in recent years, there is still a debate about whether they are appropriate for athletes. Some of the concerns include the diets overall calorie provision, protein amount and protein quality for muscle growth and recovery, gastrointestinal issues with high fibre intake, and being lower in nutrients such as iron, b12, and omega 3. We cannot forget the positive aspects of a plant-based diet, these diets, if well balanced, are rich in carbohydrates (the fuel athletes use to perform at their best), antioxidants, fibre and are high in unsaturated and low in saturated fats which are all key components of an anti-inflammatory style of diet. Athletes often wonder if they can still build muscle on a plant-based diet. Fortunately, there are two main reasons why you may see similar muscle growth and recovery as a meat-eating athlete.
A big part of the age-old debate of whether plant-based diets are good for athletes comes down to two main factors. Firstly, most plant-based protein lacks all the essential amino acids, making it an incomplete protein. This means they are missing one or more amino acids that the body cannot make and thus needs to be consumed in the diet. More specifically plant proteins are often low in leucine, which is an amino acid responsible for stimulating the buildup of muscle. It has long been thought the higher leucine spike, the more muscle buildup occurs, thus more muscle is built over time.
Secondly, protein digestibility and absorption, or how well your body digests the amino acids and appear into your blood stream, tend to be low for plant-based proteins. If you consume protein from wheat, it is estimated that about 50% of the protein is digested and able to be used in the body vs 80-95 from animal sources. This is likely because the plants contain a lot of fibre which surrounds the protein and therefore makes it more challenging for the body to break down and utilize. It seems that processing, cooking, or even sprouting may help increase the absorption of the protein to some degree.
1. How important is the leucine spike?
The relevance of the “leucine” spike has been called into question for various reasons:
Typically looking at a response from protein powders, in a fasted state.
Only studied for a short period of time.
For these reasons and others, it may not have much relevance in a whole foods diet approach.
There has also been a challenge with linking this leucine mechanism to long-term real-world outcomes that we are interested in, muscle gain!
2. “Low protein quality” Vs muscle gain
When looking at studies attempting to investigate plant protein powders and their effect on muscle building, there are quite a few that do not show any difference in body weight or muscle gain between supplementing with a plant protein vs whey (which has been the gold standard recommendation for decades). Take Banaszek et al,, 2019, for example, they conducted a study that compared pea protein to whey in trained participants. They supplemented with the protein powder before and after the training, however the catch here is that they kept their normal diet, and none of them were vegetarian or vegan, so, not incredibly helpful!
A brand-new study came out recently which piqued my interest and has also started to change my view on the outcomes of vegan or vegetarian diets in regard to muscle building (Hevia-Larrain et al., 2021). This study compared muscle size and strength gains of vegan males to that of the omnivore males after a 12-week resistance training program. It is an important fact to note that these participants were not resistance trained athletes. The study matched them for protein intake (1.6g/kg or slightly above) and calorie intake (roughly 2200kcal a day - possibly not enough for muscle gain). At the end of the study, they found there was no difference is strength (measured by a 1 rep max) or the amount of muscle gained between the two groups.
Where do we go from here?
We never like to put all our eggs in one basket, and the same goes for research. We cannot do one study and call it a day. There are still more questions to be answered before we can finally put this issue to bed.
Would you continue to see this result in the long term, say, if these participants continued to train for 1-5 years, would we then start to see significant differences in muscle gain between diet groups?
Would they still have the same results in elite or at least well-trained athletes? It is well known that an untrained individual will have an easier time building muscle compared to a well-trained individual who may be near their genetic potential for muscle mass.
At this point, my professional recommendation is that if daily protein needs and calorie needs are met, there seems to be fairly similar muscle gains between vegan and omnivore diets, but further investigation is required. However, if you are a bodybuilder who needs every ounce of muscle mass and have been training for quite some time, we cannot be sure a vegan or vegetarian diet will meet your muscle building requirements.
I also caution older athletes about adopting a fully vegan diet. This is because as we age appetite decreases and some older adults are no longer able to consume enough high-quality protein foods to meet their protein needs.
It is also important to note that older athletes (>50 years of age) start to lose 1% of muscle each year, and become resistant to the proteins they eat, meaning it takes more protein to maintain muscle mass. Therefore, you need to eat even more protein each day than a younger athlete would, which requires you to eat more food, and thus is challenging if appetite is a concern. For example, 75g of meat (roughly 1 deck of card sized portion) would provide 20g protein, whereas you would require 1 cup of lentils or edamame to provide the same amount of protein. If you are aiming for 40g per meal, 2 cups of lentils is a tall order!
So, how can we optimize our protein intake and diet supplements to support muscle growth? There are a few key foundational nutritional recommendations that I typically make.
Three tips for optimizing your plant-based diet.
Get enough overall protein each day: We need to ensure you have an adequate amount of daily protein to support growth (along with good caloric intake). This will depend on body weight; for a healthy athlete 1.6g protein per kilogram of body weight per day is a great place to start (Morton et al., 2017). Looking at the nutrition facts table, tracking on an app or working with a Registered Dietitian will help you learn how to hit your protein needs on a daily basis.
Work on protein distribution: We can then look at optimizing the protein timing. It is ideal to consume the protein spread out evenly in at least 3 meals, and an additional high protein snack (Schoenfeld & Aragon 2018). Breakfast and snacks are often the more challenging meals to get adequate protein. Options could include tofu scramble, tofu + bean wrap, roasted chickpeas, edamame or protein shakes.
Include high quality protein: Lastly consuming a variety of proteins is highly encouraged. Consuming high protein grains, nuts, seeds, beans, lentils, and soy products can help balance out the essential amino acid profiles of each other, providing you with a well-rounded amino acid intake.
If you are a vegetarian, including a few servings of dairy (Greek yogurt or cottage cheese) would be a great option, or eggs. Even better if you can include fish on occasion. If you are a vegan you may want to consider including a high leucine protein shake, especially if you cannot get enough protein from your food.
Inclusion of protein powder with a mixture of different proteins, or a pea-based protein would be most optimal for a vegan to include. You can also look to see if your powder has at least 5g of branch chain amino acids to support muscle building.
Stephanie Boville is a Registered Dietitian, sport nutritionist, and the owner of Stephanie Boville Nutrition. With her background as a former figure skater and current weight lifter, Stephanie understands the significance of properly fueling the body. She has extensive experience working with athletes of all levels, including youth, college, and professionals. Stephanie is well-prepared to assess your needs and create a personalized nutrition plan to help you achieve your performance and health goals.
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