Does a High Protein Diet Shrink Your Brain?

High protein diets have gone in and out of fashion over the years. They were most recently popularized by the Atkins diet craze that emphasized protein and fat to the exclusion of carbohydrates. While the Atkins diet proved effective for short-term weight loss, the long term effects of the diet are still unknown. The chief advantage of a diet that focuses on high protein intake is that it reduces hunger. On the downside, there’s disturbing new evidence that excessive protein intake could have a negative impact on memory and brain function.

Is High Protein Intake a Problem?: A Study

In a study published on the Food Navigator website, researchers looked at the effects of high protein intake on the brains of mice. Four groups of mice were given different diets to study the effects each would have on brain health. One group was given a high fat/low carbohydrate diet, another received a high protein/low carbohydrate diet, another a high carb/low fat diet, and still another a standard mouse diet. After eighteen weeks, brain autopsies were performed. The results? The mice that received the high protein, low carbohydrate diet had brain weights that were five percent lower than mice that received the lower protein diets. A part of the brain known as the hippocampus was also found to be underdeveloped in the mice on the high protein diet. The hippocampus is a portion of the brain involved with spatial orientation and the formation of new memories. The conclusion? At least in mice, excessive protein intake may be harmful to brain health.

Excessive Protein Intake: Is It Bad for Humans?

It’s unclear whether high protein intake in humans has the same negative effect on brain health, but there is some evidence that it does. A study conducted by the U.S. Department of Defense showed that pilots who were given a high protein diet performed more poorly on their flight performance scores than those who received a high fat or high carbohydrates date. The pilots who ate the high fat diet showed better short term memory scores, and the high carbohydrate diet group experienced healthier sleep patterns. High protein intake didn’t seem to offer any advantages to this subgroup of people and actually seemed to reduce brain function and performance.

How Much is Too Much?

Of course, a certain amount of protein in the diet is necessary, but most Americans get excessive amounts. The recommended daily intake of protein is 0.8 milligrams per kilogram of body weight which means the average, moderately active male needs between 60 and 90 milligrams per day. People who participate in vigorous exercise will require more than a couch potato. Unfortunately, most Americans are getting one-and-a-half to two times this amount. Excessive protein can be harmful to people with kidney disease or a history of kidney stones and may increase calcium loss thereby increasing the risk of osteoporosis.

The Bottom Line

A diet with too much protein may be harmful in more ways than one. Do your brain and kidneys a favor and substitute fresh fruits and vegetables for some of the meat you’re eating. It’ll be a nice change of pace.