Scientists know that eating carbohydrates can improve memory. But Canadian researchers wondered other nutrients produced similar improvements in mental functioning. They studied the effects of protein-, carbohydrate-, and fat-containing drinks in a group of healthy people in their 60s and 70s.

Researchers administered tests of cognitive performance (a paragraph recall test and a trail-making test) 15 and 60 minutes after the subjects had their drinks. They found that all three of the drinks improved paragraph recall – more so at 60 minutes than at 15 minutes. They also found:

* The carbohydrate drink improved both tests the most.
* The fat-containing drink improved attention after 60 minutes.
* The protein drink reduced forgetting on the paragraph recall test at the 15-minute mark.

As expected, blood glucose levels increased after drinking the carbohydrate. Whereas earlier studies had suggested that improvements following intake of carbohydrate may be related to increased blood glucose levels, this study documented improvements after ingesting protein and fat, which did not increase blood glucose levels in this test.

source:
Kaplan RJ, Greenwood CE, Winocur G, et al. Dietary protein, carbohydrate, and fat enhance memory performance in the healthy elderly. American Journal of Clinical Nutrition, November 2001;74(5):687-693. (Abs.)