Overview

Dr. Joyce C. McCann is an Associate Staff Scientist in the Nutrition and Metabolism Center. She and Dr. Bruce N. Ames are currently writing a series of critical review articles on causal relationships between micronutrient deficiencies and brain dysfunction. (Micronutrients comprise approximately 40 vitamins, minerals, amino acids, and fatty acids required for the body to function.) A balanced diet is essential to ensure adequate intake of every micronutrient, though inadequate intake can also be remedied by inexpensive supplements. Most of the U.S. (and world) population has intakes of one or more micronutrients well below recommended levels. This is due, in part, to high consumption of micronutrient-poor, calorie-rich refined food.

McCann and Ames argue that there is much evidence to suggest the need for an abundant supply of micronutrients to the brain to ensure optimal function. A particularly vulnerable time is during development, including the period of rapid brain growth termed the “brain growth spurt” that occurs during the last trimester of pregnancy and the first 2 years of life. During development, dietary deficiencies of some micronutrients, such as iodine and folic acid, are known to result in serious brain abnormalities, and as a result, dietary intervention programs have been implemented in many countries. A major current issue is to what degree these programs should be expanded to include additional micronutrients. Critical to that discussion is the adequacy of scientific evidence linking micronutrient deficiencies to brain health.

There is a large but less widely known scientific literature investigating effects on brain function of deficiencies of a number of micronutrients in addition to iodine and folic acid. This literature is of uneven quality and is diverse in subject matter, spanning human, animal, and in vitro systems, and including both behavioral and mechanistic studies.

McCann and Ames’ reviews are unique in that each review is the first in its field to bring together information from diverse fields in a single critical overview specifically addressing the question of causality. The reviews are third party overviews, and thus provide fresh, objective analysis of areas characterized by a great deal of scientific controversy. Additionally, the reviews are written to be accessible to a broad scientific audience, as well as to specialists. They are also being produced in different formats to make them more accessible to public health and medical professionals, as well as to the public.

The most recent review, on Vitamin D, was published in the Spring of 2008 in FASEB J. The article received high praise from Gerald Weissmann, MD, Editor-in-Chief of FASEB J:

“This critical analysis of vitamin D function and the brain is a model of careful thinking about nutrition and behavior”. One wishes that all studies of nutritional supplements or requirements were this thoughtful. Drs. McCann and Ames deftly show that while Vitamin D has an important role in the development and function of the brain, its exact effects on behavior remain unclear. Pointing to the need for further study, the authors argue for vitamin D supplementation in groups at risk.”

The vitamin D review is the fourth in the series. Other reviews discuss the long-chain polyunsaturated fatty acid docosahexaenoic acid (DHA), choline, and iron.

revised: May 16, 2008