How Much Protein Do You Need? Top Scientists Still Disagree

Dr. Gabrielle Lyon (0:00)

How much protein do we need? A person trying to avoid deficiency is asking one question. An older adult trying to preserve function is asking another. So is an athlete recovering from training, a patient recovering from illness, or someone losing weight, for example, while on a GLP-1, trying to retain lean tissue? One size doesn't fit all. Depends on age, physical activity. It also depends on personal preference. Protein is still heavily debated. Even amongst the best and the brightest. The one thing that they agreed on is that-

I'm Dr. Gabrielle Lyon, and I'm a physician. I am fellowship trained in nutritional sciences and geriatrics. I'm also board certified in family medicine, and I've been studying protein, I don't know, for the last 20 years, and protein is everywhere right now. And thank goodness, it's in coffee, cereal, cookies, chips, shakes, snack bars, you name it, walk through almost any grocery store or who knows, even a home depot, and you'll see products competing over who can place the biggest protein number on their package. And here's the strange part, despite all of the confidence that you're seeing in the marketplace, protein researchers are still debating some surprisingly basic questions. I was at the Protein Summit 3 at Texas A&M in College Station, and let me just tell you, it was so much fun. Yes, exactly right. No one wants to hang out with me on a Friday night because we'll be talking about citrulline. But the reality is that protein is still heavily debated, even amongst the best and the brightest. A recent research symposium brought together established scientists, early career researchers, and representatives from several food and agricultural organizations to wrestle through these questions. And their conclusion at Protein Summit 3 wasn't that protein is good or bad. It actually was more interesting than that. I mean, who's surprised? The one thing that they agreed on is that protein is essential, but its effects depend on the amino acids involved, the person eating the diet and also the rest of the diet.

Today, we are going to pack just a little bit of what that means. First off, protein is more than building material. We usually hear that protein builds and repairs muscle. That's true, but it is only part of the story. When we eat protein, the body breaks it into amino acids. Those amino acids help make tissues, enzymes, hormones, neurotransmitters and immune compounds. They also act as signals that tell ourselves what to do. Unlike body fat, however, the body doesn't have large storage tanks for extra amino acids. Every day, the amino acids we consume must be incorporated, transformed, oxidized or otherwise metabolized. The word oxidized sometimes sounds negative.

It can make it seem like the body is burning and wasting valuable protein. But that interpretation is just too simple.

Amino acid oxidation can be part of the body's regulatory system. It can activate signals, support energy metabolism and produce compounds that are needed elsewhere. So the question isn't merely, did this amino acid become muscle?

Because basically out there in the landscape, people will eat protein and think, okay, well, this becomes muscle. It's not really that. The better question is, what useful job did the body assign it? There are four major amino acids. I mean, there are many. There are 20 different amino acids, nine of which are essential. But to understand this broader role, consider four examples that were discussed at the symposium.

The first, this is methionine. Methionine contributes to the production of compounds such as glutathione, an antioxidant that helps the body respond to metabolic stress. It's also called the master antioxidant. Glutathione levels can decline with age, which raises the possibility that protein quality and intake could affect resilience in older adults, which I find fascinating. The second example, phenylalanine and tyrosine. These amino acids are connected to dopamine production. Dopamine is involved in motivation, mood, attention and movement. Now, this does not mean that eating more protein is a simple cure for a low mood or for concentration, but it does show that amino acids participate in brain chemistry as well as muscle biology. Again, why is this so fascinating? Because universally, we think about protein as just one thing rather than its constituents. Third, threonine. A large portion of incoming threonine is used by the gut, included for mucin production, the protective mucus layer lining in the digestive tract. That means an amino acid can be important before it ever reaches the rest of the body. Mucin production is really important to protect your digestive lining. So researchers know relatively little about how dietary protein affects this system in humans. And the gap matters because conversations about gut health usually focus on fiber and the microbiome, not on protein. Last but not least, there is my favorite, and that is leucine. Leucine is widely associated with muscle because it helps activate mTOR, which is a signaling pathway involved in protein synthesis. But leucine also interacts with insulin release, fatty acid oxidation, glutamine production, and other metabolic processes. The important lesson isn't that everyone should immediately go take leucine supplements. It is that individual amino acids have individual biological roles. Treating protein as one undifferentiated nutrient can hide that complexity. Okay, so this is the age-old topic conversation question, minimum versus optimal. That leads to the most controversial question, which is, believe it or not, how much protein do we need? The familiar adult recommendation is set at about 0.8 grams per kilogram of body weight per day. For a person weighing 70 kilograms, that's about 154 pounds. That works out to roughly 54 grams of protein. What does that number mean? Well, it generally is interpreted as an amount intended to cover the basic needs of most healthy adults. It is not necessarily a universal target for every possible outcome. Imagine this, a room full of the 100 most influential protein scientists. And they were arguing about this topic. And one of these topics was between a minimum adequate intake and an optimal intake for a particular goal. A person trying to avoid deficiency is asking one question. An older adult trying to preserve function is asking another. So is an athlete recovering from training, a patient recovering from illness, or someone losing weight, for example, while on a GLP-1 trying to retain lean tissue? One of the speakers argued that a number of metabolic outcomes appear to improve somewhere around 1.1 to 1.6 grams per kilogram per day. This should not be heard as a new universal prescription. The symposium participants were clear that the evidence is not strong enough to replace one simplistic number with another. Instead, it points towards a range shaped by context. The future may involve population categories based on life stage, physical activity, and health status, rather than one precise recommendation for every adult. So I don't know about you, but this blows my mind, right? Think about this, that a 60-year-old postmenopausal woman would have the same dietary protein recommendations as a 35-year-old guy. It's just, it's not, it's not the same. And especially if the individual amino acids, those needs change. So perhaps a truly individualized protein prescription based on genetics or detailed metabolic testing.