Plant-based diets are gaining popularity among athletes who often cite concerns over environmental sustainability, health and performance, and animal welfare as primary reasons for making the switch. In North America alone, the sale of plant-based meat alternatives grew by 37% from 2017 to 2019 .
From a sports nutrition standpoint, it’s well established that protein intake is an essential part of exercise-induced muscle adaptations, since muscle protein turnover is regulated by both exercise and nutrient intake, specifically the provision of amino acids—the building blocks of protein . So, if you’re wondering whether a plant-based diet can support your training and performance needs, read on.
What are the health benefits of plant-based diets?
What are the potential downsides?
Recently, a study found that vegans had a 43% higher risk of bone fractures than their meat-eating counterparts, specifically in the hips and legs . Vegans were more than twice as likely as omnivores to have hip fractures. Researchers attributed the increase in bone fracture risk to lower intakes of calcium, protein, and vitamin D among vegans and vegetarians.
If you are recovering from an injury or surgery, consider this: Wound healing may be delayed or impaired if you adhere to a strictly plant-based diet. Researchers in Italy found that compared to omnivores, vegans had worse outcomes from surgical scarring after 6 months, which corresponded with lower levels iron and vitamin B12 in the blood .
Are plant-based protein supplements as good for muscle rebuilding and recovery as animal-derived proteins?
Researchers from the Netherlands aimed to find out in a recent study comparing 30 g of protein from milk, wheat, or a 50/50 blend of the two sources (15 g each from milk and wheat) . They had participants consume one of the three supplements and collected blood samples and muscle biopsies to see how the amino acids from the protein affected the rate of muscle protein synthesis (MPS), the process that builds and repairs muscle tissue. Researchers found no difference in MPS rates between the three sources, suggesting the plant-based protein performed just as well as the milk .
From a longer-term perspective, researchers found no difference in muscle mass or strength gains following four weeks of resistance training plus either soy or whey protein supplements in healthy young men who were either habitual vegans or omnivores . Importantly, they made sure that both groups received the same amount of protein daily (1.6 grams per kilogram of body weight), which is a common pitfall in studies comparing plant-based versus omnivorous diets. The takeaway here is that with sufficient total protein intake, strength and muscle mass gains are similar, regardless of whether it’s from plant-based or animal sources.
Other considerations for athletes adopting a plant-based diet
One or more key essential amino acids, such as leucine, lysine, and methionine are typically limited in plant-based protein sources compared to animal-derived ones. To make sure you get the full spectrum of essential amino acids, eat a variety of plant-based proteins (soy, hemp, lentils, whole grains, nuts and seeds) to meet your daily intake needs, aiming for about 1.6 grams of protein per kilogram of bodyweight per day. Adequate dietary protein improves recovery from training and promotes muscle repair and rebuilding.
Age plays a big role in the muscle rebuilding response to a given protein dose, highlighting the phenomenon known as “anabolic resistance” among older athletes. As you age, larger amounts (30-40 g protein per meal) may be required to support athletic goals and training .
As with any supplement, be sure to find a plant-based protein supplement that has been third party tested for purity and potency. Contaminants such as arsenic, cadmium, lead, other heavy metals have been detected in several top-selling vegan protein powders.
Although convenient, most plant-based meat substitutes are considered “ultra-processed foods” (think meatless burgers, nuggets, and crumbles). A recent study found that ultra-processed food intake led to increased energy intake and weight gain relative to whole foods, leading the authors to conclude that “Not all vegetarian diets necessarily have health benefits, because of potential adverse effects of UPFs [ultra-processed foods] on nutritional quality and healthiness of diet.” 
Iron, calcium, vitamin B12, zinc, and creatine supplementation may be warranted if not supplied in sufficient amounts through dietary intake, as these are either 1) found primarily in animal-derived products, or 2) not as bioavailable when consumed from plant-based sources (such as calcium, zinc, and iron). Consult with your primary care physician or sports dietician to determine if supplementation is right for you.
Bottom Line: Adopting a vegan or vegetarian lifestyle is a highly personal decision, and factors aside from health and performance undoubtedly play a role. However, athletes considering making the switch should be aware that they have heightened dietary needs which should be met through a variety of plant-based sources, and that supplements and ultra-processed meat and dairy alternatives may not confer the same health-promoting benefits commonly associated with plant-based eating. If you are going to make the switch, careful attention must be paid to micronutrient status, total energy intake, and protein intake to support your training and recovery needs.