From The December 2000 Issue of Nutrition Science News
A cognitive test shows lack of vitamin B12 (cobalamin) during the formative first six years of life could result in long-term reduced cognitive function. Researchers from the Nutrition and Food Research Institute in Zeist, Netherlands, studied children who had been raised on a strictly vegan macrobiotic diet until age six. The children ate a lactovegetarian or omnivorous diet after that age.
Between ages 10 and 16, the 48 adolescents underwent a series of tests designed to determine cognitive function. They were compared with 24 adolescents fed omnivorous diets from birth. The psychological tests were designed to measure fluid intelligence, spatial ability, concentration, short-term memory, psychomotor development and information-processing speed. Although all of the early macrobiotic children had been consuming vitamin B12 for several years before the test, almost two-thirds were found to be B12 deficient as determined by either low serum cobalamin or an elevated concentration of methylmalonic acid, a marker for B12 deficiency. Almost a third still had B12 intakes below 50 percent of the Recommended Daily Allowance. The control subjects, all of whom had normal B12 status, performed better on most psychological tests including those measuring fluid intelligence, spatial ability and short-term memory than those who had been macrobiotic. Those who were still deficient in B12 performed worst of all.
This research is intriguing but far from definitive. It is already known that vitamin B12 deficiency causes neurological damage that can be permanent. However, the researchers admit they examined too few subjects to draw meaningful conclusions. For example, in some cases the macrobiotic subjects performed better than the controls, and in other cases the B12-deficient subjects performed better than those with adequate B12 status. The researchers dismissed these findings. Additional research is needed to clarify whether a relationship truly exists between vitamin B12 and cognitive function.
Signs of impaired cognitive function in adolescents with marginal cobalamin status
American Journal of Clinical Nutrition 2000 (Sep); 72 (3): 762-769