Signs of impaired cognitive function in adolescents with marginal cobalamin status

Am J Clin Nutr. 2000 Sep;72(3):762-9. doi: 10.1093/ajcn/72.3.762.


Background: Lack of cobalamin may lead to neurologic disorders, which have been reported in strict vegetarians.

Objective: The objective of this study was to investigate whether cognitive functioning is affected in adolescents (aged 10-16 y) with marginal cobalamin status as a result of being fed a macrobiotic diet up to an average age of 6 y.

Design: Data on dietary intake, psychological test performance, and biochemical variables of cobalamin status were collected from 48 adolescents who consumed macrobiotic (vegan type) diets up to the age of 6 y, subsequently followed by lactovegetarian or omnivorous diets, and from 24 subjects (aged 10-18 y) who were fed omnivorous diets from birth onward. Thirty-one subjects from the previously macrobiotic group were cobalamin deficient according to their plasma methylmalonic acid concentrations. Seventeen previously macrobiotic subjects and all control subjects had normal cobalamin status.

Results: The control subjects performed better on most psychological tests than did macrobiotic subjects with low or normal cobalamin status. A significant relation between test score and cobalamin deficiency (P: = 0.01) was observed for a test measuring fluid intelligence (correlation coefficient: -0.28; 95% CI: -0.48, -0.08). This effect became more pronounced (P: = 0.003) within the subgroup of macrobiotic subjects (correlation coefficient: -0.38; 95% CI: -0.62, - 0.14).

Conclusion: Our data suggest that cobalamin deficiency, in the absence of hematologic signs, may lead to impaired cognitive performance in adolescents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Child
  • Cognition Disorders / etiology
  • Cognition*
  • Cohort Studies
  • Diet, Macrobiotic
  • Female
  • Humans
  • Intelligence
  • Male
  • Psychological Tests
  • Psychomotor Performance
  • Reference Values
  • Vitamin B 12 / blood*
  • Vitamin B 12 Deficiency / complications
  • Vitamin B 12 Deficiency / psychology


  • Vitamin B 12