Dietary protein, carbohydrate, and fat enhance memory performance in the healthy elderly

Abstract

Background: Dietary carbohydrates can improve memory. Whether these effects are related to elevations in blood glucose or to energy ingestion is unknown. Objectives: Our objectives were to determine 1) the influence of isoenergetic protein-, carbohydrate-, and fat-containing drinks on cognitive performance and 2) whether the time period after ingestion affects cognition. Design: After fasting overnight, 11 men and 11 women aged 61-79 y consumed either a 300-mL drink containing 774 kJ as pure protein (whey), carbohydrate (glucose), or fat (safflower oil) or a nonenergy placebo on 4 separate mornings. Cognitive tests were administered 15 and 60 min after ingestion of the drinks. Plasma glucose and serum insulin concentrations were measured. Results: Only the carbohydrate drink increased blood glucose (P < 0.0001). Compared with the placebo, all 3 macronutrients improved delayed paragraph recall (PR) (P < 0.001) and improved or tended to improve immediate PR (P < 0.04) 15 min after ingestion. Beneficial effects on other cognitive tests were confined to one or more of the macronutrients: carbohydrate improved Trail Making Test (Trails) performance at 60 min (P = 0.02) and tended to improve Trails at 15 min (P = 0.04) and PR at 60 min in men, carbohydrate and fat improved or tended to improve performance on Trails at 15 and 60 min in subjects with poor baseline scores (r > Ϫ0.41, P < 0.03), fat tended to improve attention at 60 min (P < 0.05), and protein reduced the rate of forgetting on the PR at 15 min (P = 0.002). Conclusions: Energy intake from protein, carbohydrate, or fat can enhance memory independently of elevations in blood glucose. Each macronutrient may also exert unique effects on cognition.Am J Clin Nutr 2001;74:687-93.

Influences of protein to energy ratios in breakfast on mood, alertness and attention in the healthy undergraduate students

“…In addition, several studies showed that eating breakfast can improve cognitive performance and attention-concentration compared with omitting breakfast [18][19][20], but the effect of each macronutrient was not defined because of various methodologic issues. In fact, the study [21] about the relationship of macronutrients and memory performance indicated all of the macronutrients improved paragraph recall 15 min after ingestion, suggesting that energy intake can enhance specific aspects of cognition, in addition to the effects of energy ingestion on memory, each macronutrient enhanced performance on various tasks, possibly via unique mechanisms. Indeed, all three kinds of macronutrients led to an initial, robust improvement on delayed paragraph recall.…”

“…Indeed, all three kinds of macronutrients led to an initial, robust improvement on delayed paragraph recall. Each macronutrient may exert different effects on cognition by additional, unique mechanisms [21]. Human beings should not ingest pure protein, carbohydrate, or fat, but should pay attention to the content of the various macronutrients reasonably matched.…”

Acute tryptophan depletion in humans: a review of theoretical, practical and ethical aspects

“…The 25 g mixture will obviously provide only 25% of the caloric load of the 100 g mixture, so greater feelings of hunger would be expected 5-7 hours after the mixture ingestion, which is when measures are usually obtained. Furthermore, when humans ingest a meal, it enhances memory, 96 which raises the possibility that memory will be enhanced by the 100 g mixture relative to the 25 g mixture 5 hours later. For these reasons, the use of a 25 g control mixture is not recommended, and results obtained using this methodology should be accepted with caution.…”

Effect of Sugars in Solutions on Immediate and Delayed Word List Recall in Normal Weight Boys

“…Girls, but not boys, recalled more words after consuming the milk-containing beverages, suggesting that both sex and macronutrient composition interact to affect memory performance. In healthy older adults (12), despite difference in the glycemic response, both dietary protein and fat improved memory performance similar to carbohydrate. Thus, multiple mechanisms other than an increase in blood glucose contribute to improvements in memory performance.…”