by Chris Shugart
Your brain needs amino acids to function properly, but what fuels it better, plant or animal proteins? Here's the answer.
Dietary choices are a lot like politics: the people at the extreme ends are idiots. In nutrition, we have the vegans vs. the carnivores. One side won't eat meat; the other side only eats meat. But our bodies are independent voters, designed to thrive when we consume both plants and animals.
Now that we've weeded out the extremists, let's rationally look at a new study that pits plant protein intake against animal protein intake. Here's the spoiler: Researchers found that animal proteins protect the brain from aging. Plant proteins don't.
First, let's look deeper into this study, then let's see if the researchers missed anything. (I think they did.)
The Study
If you want to stay mentally sharp, avoid cognitive diseases, and be happy, then you want a juicy brain, primarily a hefty hippocampus. People with Alzheimer's lose hippocampus volume, and so do people with depression. In short, shrinkage is bad, but it's hard to avoid as you age.
In this study, researchers wanted to see if the type of protein we consume affects brain health. Protein is a fundamental component of neurotransmitters and neurons, contributing to brain maintenance and function. A very low-protein diet ages the brain faster. But what's better, plant or animal protein?
The researchers studied 2723 people for three years, had them track their diets, then euthanized them and weighed their brains. Wait, let me double-check that. Nope, sorry, they just did lots of brain scans. Makes more sense. Here's the quick version of what they found:
- Those who got most of their protein intake from animal sources experienced protective effects and showed less brain atrophy as they aged.
- Those who got most of their protein intake from plant sources didn't experience the protective effects and showed a faster rate of brain shrinkage (less hippocampus volume).
- The animal-protein eaters had even better results if seafood was a weekly part of their diets.
Why the Difference?
According to the researchers, animal proteins are better brain food because of their amino acid composition. Also, animal protein is generally more easily absorbed and utilized by the human body, with higher biological availability.
Animal protein typically contains all the essential amino acids (EAAs). The composition and proportion of amino acids in animal protein are similar to those in our bodies. But plant protein often lacks (or has lower levels of) certain EAAs, such as BCAAs, especially leucine, tryptophan, and lysine, making it an incomplete protein. Low BCAA levels impair the brain, and leucine plays a key role in brain health. It's hard to get enough leucine from plant sources.
Leucine appears to be a crucial donor of nitrogen in the brain, participating in the glutamate-glutamine cycle. Glutamate is a major excitatory neurotransmitter and regulates several brain functions. The cycle between glutamate and glutamine is restricted due to low brain BCAA levels, leading to the accumulation of glutamate and ammonia and resulting in neurotoxicity and neurodegenerative changes that weaken brain health.
Reduced levels of brain BCAAs also diminish protein synthesis, impacting the repair of brain tissue, synaptic growth, and remodeling. Finally, a lack of brain BCAAs leads to neuroinflammation and causes all sorts of problems.
Do They Miss Something?
Yeah, the seafood thing. The researchers were correct about BCAAs and brain health, and yes, most seafood is a good, complete source. But what else does seafood contain? Omega-3 fatty acids: DHA and EPA. Our brain cell membranes are literally made of omega-3s, and low intake (particularly of DHA) is associated with cognitive decline (related to brain inflammation and shrinkage), depression, and anxiety.
The study was correct: animal proteins are better than plant proteins. But the researchers should've factored in the omega-3 fatty acid content of the seafood, and not just the amino acid profile. That played a role too.
How to Use This Info
Plants are an ancillary source of protein; you eat them primarily for their other components. But your body was simply designed/evolved to get most of its protein needs met through animal sources. It's true for muscles and it's true for brains.
But you don't have to live on meat. Remember, animal proteins include eggs and dairy. Milk-derived proteins like whey and micellar casein are best for muscles, and given their high leucine content, probably best for brains. MD Protein (Buy at Amazon) contains a blend of both types.
Likewise, your brain runs on omega-3s, so prevent shrinkage by taking fish oil. Flameout DHA-Rich Fish Oil (Buy at Amazon) contains five times more DHA than EPA, which keeps your brain juicy and happy.
A Final Word on Plant Proteins
Even when fortified with leucine and other EAAs, plant protein powders remain inferior to the MPS horsepower of a whey isolate–micellar casein blend. However — and this is not a paid promotion — if you choose a plant protein, RISE311 is clean and strategically augmented to maximize performance — making it the strongest option the plant world has to offer.
Reference
- Cui, et al. "The Association between Dietary Protein Intake and Sources and the Rate of Longitudinal Changes in Brain Structure." Nutrients 2024, 16(9), 1284.