Chapter 132
Probably Not Whey
To my surprise, neither milk nor milk protein was able to increase muscle mass. After all, milk is naturally designed so that a calf gains a few hundred pounds within a few months. Whey is the protein that stimulates the strongest response with respect to short-term muscle protein synthesis, probably due to its high concentration of leucine, the mTOR-triggering amino acid. (As you surely remember from the chapter on mTOR: This enzyme accelerates growth, but sometimes also aging.) Even pure leucine supplements do not lead to muscle building. But if leucine stimulates muscle protein synthesis, why doesn’t that lead to more muscle mass?
Muscle tissue is in constant flux. Every day, 2 percent of our total musculature is affected. Scientists gave subjects a bolus of specially labeled protein and were able to track the protein’s path through the body. After a few hours, about 10 percent of it was stored in the muscles. In other words: We are what we just ate. Surprisingly, however, there is no correspondence between these acute changes in the formation of muscle protein and long-term changes in muscle mass, as MRI scans confirm.
We used to believe the timing of protein intake was important and that there was only a small window of time immediately after training to promote muscle growth. But here, too, the same applies: Short-term measures do not guarantee long-term results. Instead, resistance training appears to increase the muscles’ overall capacity to form protein whenever protein is available. This insight led to the dismantling of another protein myth—namely, that it is better to spread protein intake across the day because muscle protein synthesis maxes out at a certain dose. In practical tests, the opposite turned out to be true.
This also explains why plant proteins can build muscle mass just as well as animal proteins. Although, for example, acute muscle protein synthesis from whey protein is stronger in the first hours after consumption than with soy protein, the gain in muscle mass and strength is the same. Not even studies funded by the National Cattlemen’s Beef Association itself using beef were able to demonstrate a difference, nor were the studies funded by the American Egg Board on eating eggs as a benefit for muscles. JUST Egg, by contrast, a plant-based omelet made from mung beans, did appear to improve muscle strength—at least in a kind of post-hoc analysis of an eight-week randomized controlled trial.
Ultimately, whey protein therefore at most causes you to suffer the side effects of additional mTOR activation. On the surface, in athletes and bodybuilders, that includes acne when they consume whey proteins. More importantly, dermatologists write in an article that restricting dairy products could help “prevent serious mTOR-related diseases of civilization such as obesity, diabetes, and cancer.” In an attempt to slow muscle wasting in mice with cancer, scientists gave the animals leucine, but this only led to a doubling of tumor growth. The isoflavone phytoestrogens in soy can do the opposite—they suppress mTOR, at least in mice—while in a randomized placebo-controlled double-blind study they increased the lean mass of human limbs independently of protein. Isoflavones alone increased limb lean mass at a daily dose equivalent to about three quarters of a cup of tempeh, two thirds of a cup of cooked soybeans, or a half cup of soy nuts.
Prefer plant protein
The association between plant-based eating and muscle mass, strength, and function is not yet clear, but some studies have shown that plant protein in particular is associated with a lower risk of sarcopenia, pre-frailty, and frailty, with better physical performance and more successful aging. The calculation used functional impairments, self-rated vitality, mental health, chronic diseases, participation in social activities with friends and family, as well as the number of annual outings. Scientists suspect that the condition could be due to differences in the proteins themselves, such as the lower methionine content of plant proteins, which I discuss in the chapter on protein restriction, but it could also be due to the food components that accompany proteins from animal sources.
Foods are a total package. On the Harvard School of Public Health website on protein, you will find that for health, the source and not the amount of protein is what matters. That is because foods are a “protein package” that can contain saturated fats and sodium on the one hand, but also antioxidants and fiber on the other. Therefore, the most important tip for optimal protein selection is: Get your protein from plants as much as possible.
Aren’t plant proteins inferior and incomplete?
All nutrients come from the sun or from the soil. Vitamin D, the “sunshine vitamin,” is formed when skin is exposed to sunlight; everything else comes from the soil. Minerals come from the earth, vitamins from the plants and microorganisms that grow out of the earth. The calcium in a cow’s milk (and in its 100-kilo skeleton) comes from all the plants it ate, which in turn had taken it up from the soil. But we can skip the cow and get calcium directly from plants.
Where does protein come from? Protein consists of a series of amino acids, most of which we can produce ourselves. Some, however, are “essential,” vital, meaning our body cannot produce them itself and therefore we must take them in through food. Animals don’t produce them themselves either. All essential amino acids come from plants and microbes, and all plant proteins contain all essential amino acids. The only truly “incomplete” protein in food is gelatin, which lacks the amino acid tryptophan, so the only protein source we cannot live on is Jell-O.
People who eat a strictly plant-based diet consume on average about 20 percent more protein than the recommended daily amount. Anyone who doesn’t know where to get protein on a plant-based diet doesn’t know beans. (Legumes like beans, split peas, chickpeas, and lentils are the protein superstars of the plant kingdom, but all plant foods contain more or less protein.) So there is enough protein. But what about its quality?
The notion that plant protein is inferior to animal protein goes back to rodent studies more than 100 years old. At the time, researchers observed that young rats grew less well on a plant-based diet. However, they also do not grow as well on human breast milk. Does that mean we should not breastfeed our babies? No, of course not! Rat milk contains ten times more protein than human milk, because rat pups grow about ten times faster than babies.
It is true that some plant proteins contain only small amounts of certain essential amino acids. That is how, almost 50 years ago, the myth of “protein combining” arose—seriously, in the February 1975 issue of Vogue. As I explain in see.nf/combining, this absurdity was already refuted decades ago. Outdated concerns about the digestibility of plant protein were effectively rebutted on the basis of updated human data. From muscle biopsies, DXA scans, ultrasound examinations, and strength tests, we know that resistance training leads to comparable muscle gains in vegans and omnivores.
Antioxidants against age-related muscle loss?
Antioxidants could be a muscle-preserving component of the plant-protein package. Oxidative stress is thought to play a central role in the development of sarcopenia. For example, mice that lack an important antioxidant enzyme suffer from dramatically accelerated age-related muscle loss, and some epidemiological studies see a connection between increased intake of antioxidants, greater grip strength, and higher walking speed. Human muscles respond strongly to vitamin C intake. Just half a kiwi can triple the concentration in the muscles, since an estimated two thirds of the body’s vitamin C accumulates there.