Effects of vitamins and trace elements on cognitive function - Vitamins and Minerals - Brief Article

Nutrition Research Newsletter, Nov, 2001

Aging is associated with a gradual impairment in cognitive function and mild dementia. The elderly also show a high prevalence of deficiencies of certain nutrients. Many nutrients play a key role in the metabolism of neuronal cells. There have also been studies that show that micronutrients aid in the ability of immune cells to withstand the toxic effect of inclusion bodies found in brains of patients with Alzheimer's disease.

Therefore, nutritional deficiencies may be a contributing factor, perhaps even a causal factor, in the decline of cognitive function in old age. A Canadian researcher tested the hypothesis that an optimum intake of all essential micro-nutrients improves cognitive function in the elderly.

Eighty-six healthy, independent men and women above 65 years of age were included in the study. The subjects were randomly placed into two groups where they either received a placebo or a supplement of trace elements and vitamins daily for 12 months. Blood samples were obtained at one-week intervals to test for nutrient levels. Cognitive function was assessed by several tests that gauge immediate and long-term memory, abstract thinking, problems-solving ability and attention.

At the baseline, the prevalence of nutrient deficiency did not differ significantly between groups. There was no significant change in the nutrition status of the placebo group at the end of the year period. However, there was a significant reduction in the prevalence of deficiencies of vitamin A, beta-carotene, vitamin [B.sub.6], vitamin C, iron and zinc in the supplemented group. The supplemented group also showed a significant improvement in all cognitive tests except long-term memory recall, while the placebo group showed no change in cognitive function. The subjects who showed deficient blood levels of one or more nutrients showed lower responses on all cognitive function tests. There was no significant relationship between levels of individual nutrients and cognitive function test scores.

The results showed that cognitive functions improved after oral supplementation with modest amounts of vitamins and trace elements. Chandra hypothesized that the enhanced immune response in those receiving the vitamin supplement maybe instrumental in preserving the anatomy and function of neurons and their appendages. Since there is no evidence to suggest that modest amounts of vitamins and trace elements have any toxic or adverse consequences, Chandra recommends that the elderly take such a supplement. More research is needed but the author is also interested in long-term studies that might show how supplementation affects the onset and progression of Alzheimer's disease.

Ranjit Kumar Chandra. Effect of vitamin and trace-element supplementation on cognitive function in elderly subjects. Nutrition 17: 709-712 (September 2001) [Address correspondence to: Ranjit Kumar Chandra, MD, FRCPC, MACP, Janeway Child Health Center, St. John's, NF A1A 1R8, Canada. E-mail: rchandra@mun.ca.]