Could Eating More Protein Help Keep Your Brain Sharp?

A long-term study shared by Harvard Health looked at how what we eat might affect our brain health over time.

The researchers followed over 77,000 adults for more than 20 years and found something interesting: people who ate more protein—especially instead of carbohydrates—were less likely to experience memory loss or cognitive decline as they aged.

Here’s the big takeaway: swapping just a small portion of daily calories (about 5%) from carbs to animal protein was linked to an 11% lower chance of developing dementia. Even more striking, switching those same calories to plant-based protein (like beans or lentils) was tied to a 26% drop in dementia risk.

Among all plant protein sources, beans and legumes—especially peas and lima beans—stood out. Adding just three extra servings per week was associated with a 28% lower chance of cognitive decline.

Now, this doesn’t prove that eating more protein directly prevents dementia. It’s what’s called an observational study, so it shows patterns, not cause and effect. Still, protein is essential for your body. It helps repair tissues, supports muscle and organ function, and plays a role in making chemicals your brain needs to work well.

The bottom line? Making space on your plate for more protein-rich foods—especially plant-based ones like beans, nuts, seeds, and lentils—might be a smart move for your brain and your overall health.