Nutrient Energy Boosts Short-Term Memory

Source: Tufts University
January 11, 2002 (Reviewed: January 26, 2004)

The link between nutrition and learning is usually focused on children, but people of all ages need a steady supply of nutrients in order to think clearly. A Canadian study published the American Journal of Clinical Nutrition suggests that the energy-producing nutrients - protein, carbohydrate, and fat - all help fuel short-term memory functions.

Nutrient Analyses

In a repeated-measures crossover design analysis, 22 men and women aged 61 to 79 years consumed (in a fasting state) 300 mL of one of four beverages every morning for four days: 774 kJ drinks made up of pure protein (whey), carbohydrate (glucose), or fat (safflower oil), or a calorie-free placebo. The beverages were flavored with artificial sweetener and lemon to mask the taste as much as possible. Three types of memory tests - paragraph and word list recalls, 'trail tests' designed to assess mental flexibility and motor function, and attention tests - were administered 15 and 60 minutes after beverage consumption. Plasma glucose was measured at the 15, 60, and 90 minute marks.

Nutrients fuel memory functions

Consumption of all three macronutrient drinks improved delayed recall in the paragraph recall test; when the test was administered 15 minutes after beverage consumption, the protein drink was associated with a reduced number of forgetting errors when compared with placebo (p=0.002). Consumption of the carbohydrate and fat beverages enhanced men's performance on the 'trails test', which required participants to connect consecutive numbers or letters listed in random order on a page. None of the beverages affected the scores of the attention tests given 15 minutes after consumption. But consumption of the fat-containing beverage, compared with placebo, was associated with improved scores on the delayed (60 minutes) attention tests.

The mental boost that breakfast provides is usually associated with carbohydrate intake, since an elevated blood glucose concentration increases the uptake and utilization of glucose by brain cells and stimulates the synthesis of acetylcholine. This study, however, suggests that energy from all food sources promotes short-term memory, possibly due to the release of gastrin-releasing peptides, which, in turn, stimulate the vagus nerve, sending impulses from the gut to the brain. Moreover, each macronutrient may affect specific types of cognitive function, depending on the area of the brain that controls that function.

Breakfast important at any age

The message of this report is that all foods contribute the energy needed for good cognitive function. Seniors who eat sparsely or who subsist on easy-to-fix carbohydrate foods like toast and cereal may be not be getting the nutrients they need to support healthy short-term memory skills. The authors suggest that clinicians consider diet when they evaluate a patient who is showing signs of mild cognitive impairment, since improved nutrition may help slow the decline.

Source

• Dietary protein, carbohydrate, and fat enhance memory performance in the healthy elderly. R. Kaplan, E. Greenwood, G. Winocur,  et al., Am J Clin Nutr, 2001, vol. 74, pp. 687--693

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