High-Protein Diets Shrink the Brain

NEW YORK – Many recent studies have shown that diets rich in vegetables, fruits, nuts, and fish are good for the brain and may delay the onset or slow the advance of Alzheimer’s disease.

But a new study found that a high-protein diet appears to lead to a smaller brain.

A research team from the United States, Canada, and United Kingdom studied four different types of diets on mice that were bred to express a mutant from of human amyloid precursor protein (APP).

The body uses APP to produce the amyloid plaques associated with Alzheimer’s. Mice were fed a regular diet, a high-fat/low-carbohydrate diet, a high-protein/low-carb diet, or a high-carb/low-fat diet.

The researchers then studied the mice’s brains and bodies, evaluating the plaque buildup and differences in specific regions of the brain associated with memory deficit and Alzheimer’s.

Surprisingly, the mice fed the high-protein/low-carb diet had brains 5 percent smaller than mice in the other three groups, and areas of their hippocampus were less developed. The researchers speculated that the high-protein diet may make the brain’s neurons, which transmit nerve impulses, more susceptible to the Alzheimer’s-associated plaques.

But what does this study mean for humans? “One wonders whether particular diets, if ingested at particular ages, might increase susceptibility to incidence or progression” of Alzheimer’s, said lead author Sam Gandy, a professor at The Mount Sinai School of Medicine. The only way to know for sure would be double-blind clinical tests.