Vitamin B-12 from algae appears not to be bioavailable

Am J Clin Nutr. 1991 Mar;53(3):695-7. doi: 10.1093/ajcn/53.3.695.


The effect of algae (nori and spirulina) and fermented plant foods on the hematological status of vitamin B-12-deficient children was evaluated. Although rising plasma vitamin B-12 concentrations in children consuming only plant foods (0.1-2.7 micrograms vitamin B-12/d) indicated that the vitamin B-12 was absorbed, elevated baseline values of mean corpuscular volume (MCV) further deteriorated. In contrast, MCV improved in children receiving fish containing 0.15-0.5 microgram vitamin B-12/d or a vitamin B-12 supplement. Further studies on the specificity of current vitamin B-12 assays are warranted. It seems unjustified to advocate algae and other plant foods as a safe source of vitamin B-12 because its bioavailability is questionable.

MeSH terms

  • Animals
  • Biological Availability
  • Child, Preschool
  • Erythrocyte Indices
  • Eukaryota*
  • Fermentation
  • Fishes
  • Humans
  • Infant
  • Plants, Edible*
  • Vitamin B 12 / blood
  • Vitamin B 12 / pharmacokinetics*


  • Vitamin B 12