Vitamin B-12: low milk concentrations are related to low serum concentrations in vegetarian women and to methylmalonic aciduria in their infants

Am J Clin Nutr. 1990 Dec;52(6):1073-6. doi: 10.1093/ajcn/52.6.1073.


In a group of 13 strict vegetarian and 6 omnivorous lactating women, relationships were studied among maternal milk and serum vitamin B-12, and milk vitamin B-12 and infant urinary methylmalonic acid (MMA) excretion. Milk vitamin B-12 concentrations were lower in women consuming a strict vegetarian diet compared with an omnivorous diet. Milk vitamin B-12 was inversely related to length of time on a vegetarian diet and positively correlated with maternal serum vitamin B-12 concentrations. Infant urinary MMA excretion was inversely related to milk vitamin B-12 concentrations less than 362 pmol/L. The 1989 recommended dietary allowance for vitamin B-12 of 221 pmol/d for infants is close to the intake below which infant urinary MMA excretion is increased. We conclude that the current RDA for infants provides little margin of safety.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Diet, Vegetarian / adverse effects*
  • Humans
  • Infant
  • Lactation
  • Male
  • Methylmalonic Acid / urine*
  • Milk, Human / chemistry*
  • Time Factors
  • Vitamin B 12 / analysis*
  • Vitamin B 12 / blood


  • Methylmalonic Acid
  • Vitamin B 12