Marginal Vitamin [B.sub.12] Status Leads to Poor Test Performance in Teens.

Vitamin [B.sub.12] deficiency has long been known to lead to both anemia and severe neurological (nervous system) problems. Dutch researchers examined adolescents between 10 and 16 years who had followed a macrobiotic diet up to about age 6, after which they followed either lacto-ovo vegetarian or non-vegetarian diets. Before age 6, the study subjects' diets consisted mainly of cereals, dried beans, and vegetables and were very low in vitamin [B.sub.12]. Subjects of this study had been found to have vitamin [B.sub.12] deficiency when they were 9-15 years old. They were compared to other adolescents who had been macrobiotic but did not have signs of vitamin [B.sub.12] deficiency as well as to non-vegetarians. Subjects who were formerly macrobiotic tended still to have diets that had less than the recommended level of vitamin [B.sub.12]. All subjects received a battery of psychological tests designed to measure reasoning, problem solving, spatial ability, attention and concentration, memory, creativity, eye-hand coordination, and other functions. In general, scores on the psychological tests tended to be higher in non-vegetarians than in subjects who had followed a macrobiotic diet and who had either low or normal vitamin [B.sub.12] status. Vitamin [B.sub.12] status was especially associated with tests measuring problem solving, abstract thinking ability, spatial ability, reasoning, and short-term memory, with those subjects with the worst vitamin [B.sub.12] status tending to have the greatest defects in performance. The results of this study do not tell us whether early vitamin [B.sub.12] deficiency leads to life-long impairment or whether the subjects' diets simply did not contain enough vitamin [B.sub.12] to make up for their deficiency early in life. Regardless, this study points out the importance of making sure that all children have diets that contain adequate amounts of vitamin [B.sub.12]. Sources of vitamin [B.sub.12] for vegans include vitamin [B.sub.12] fortified soymilks, breakfast cereals, meat analogs, nutritional yeast (Vegetarian Support Formula), and vitamin [B.sub.12] supplements.

Louwman MWJ, van Dusseldorp M, van de Vijver FJR, et al. 2000. Signs of impaired cognitive function in adolescents with marginal cobalamin status. Am J Clin Nutr 72:762-9.