New studies say it’s possible to rely on plant protein without sacrificing training gains

At the 1936 Berlin Olympics, a scientist named Paul Schenk studied the eating habits of top athletes from around the world. Canadians reported plowing through more than 800 grams of meat per day on average; Americans drink more than two liters of milk a day.

Although there have been many changes in sports nutrition since then, the belief that meat and dairy products are the best fuel for building muscle. Nowadays, however, a growing number of athletes are interested in reducing or eliminating their dependence on animal proteins, for environmental, ethical or health reasons. A couple of new studies bolster the case that it’s possible to rely on plant-based protein without sacrificing training gains, as long as you choose your proteins carefully.

The standard objection to plant proteins is that they lack the right combination of essential amino acids needed to build new muscle fibers. Unlike animal proteins, most plant proteins are missing or low in at least one essential amino acid.

In particular, there is one specific amino acid, leucine, that seems to play a special role in activating the synthesis of new muscle. It is especially rich in whey, one of two proteins (along with casein) found in milk. That’s why whey protein is the drink powder of choice in gyms around the world, backed by decades of compelling research, often funded by the dairy industry.

But one of the reasons whey seems so good may be that we haven’t fully explored the alternatives. A 2018 study by Luc van Loon of Maastricht University in the Netherlands, for example, tested nine plant proteins, including wheat, hemp, soy, brown rice, peas and corn. To their surprise, they found that corn protein contains 13.5% leucine, even more than whey.

Based on this insight, van Loon decided to pit corn against milk in a direct test of muscle protein synthesis. The volunteers consumed 30 grams of one of the proteins; a series of blood tests and muscle biopsies were collected over the next five hours to determine how much of the ingested protein was being converted into new muscle fibers. The results, which appeared in the journal Amino Acids, were simple: despite all the hype about the serum, there was no discernible difference between them.

A second study, this one published in Medicine & Science in Sports & Exercise by a team led by Benjamin Wall of the University of Exeter in Great Britain, had similar findings. Instead of corn, he used a mix of 40% peas, 40% brown rice and 20% canola protein. Because different plants have different amino acid profiles, mixing complementary proteins has long been suggested as a way to overcome deficiencies in any plant protein. Indeed, the protein blend triggered muscle synthesis as new as the serum.

At first glance, the message from these studies is simple: plant proteins are, or at least can be, as effective as the best animal proteins in supporting muscle growth. However, there are some caveats to be aware of. One is that the studies used protein powder isolates instead of whole foods. You need almost nine cobs of corn to get the 30 grams of protein used in Van Loons’ study, compared to just three and a half cups of milk.

Another is that plants are generally more difficult to digest, which means that not all amino acids will be able to be used. This may not be a problem for healthy young adults who consume 30 grams of protein at a time, which is enough to trigger a near-maximal muscle response. But for older people, who tend to have strong muscle-building responses to protein, or in situations where you’re getting a smaller dose of protein, the details of protein quality may be more important.

Of course, the effectiveness of plant proteins won’t be news to notable plant-based athletes like ultrarunner Scott Jurek or basketball star Chris Paul, but it’s encouraging to see that science is finally starting to catch up.

Alex Hutchinson is the author of Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. Follow him on Threads @sweat_science.