Apparently healthy Indian lactovegetarians have significantly lower serum levels and urinary excretion of vitamin B₁₂ as compared to non-vegetarians. The low levels of serum vitamin B₁₂ in lactovegetarians are not due to defective absorption but to low dietary intake of this vitamin. Inspite of considerably low serum vitamin B₁₂ values, the lactovegetarians have no apparent signs or symptoms of vitamin B₁₂ deficiency and their response to injected cyanocobalamin mixed with tracer radioactive B₁₂, as judged by urinary excretion pattern and liver uptake, was similar to that observed in non-vegetarians.

Plasma and erythrocyte vitamin B12 was measured in apparently healthy Indian lactovegetarians and compared with the healthy non-vegetarians from the same population. Comparison of the mean values for routine haematological parameters revealed no significant difference in various dietetic groups. The plasma vitamin B12 levels were distinctly lower in the lactovegetarians than in the non-vegetarians. However, the mean erythrocyte vitamin B12 levels in different dietetic groups showed no significant difference.

Plasma and erythrocyte vitamin B₁₂ levels were studied in pregnant Indian women consuming very little food of animal origin and compared with healthy non-pregnant women from the same dietetic group. The comparison of the mean values for routine haematological parameters revealed distinct fall in haemoglobin, packed cell volume, plasma vitamin B₁₂, and albumin levels in pregnant women. However, the mean erythrocyte vitamin B₁₂ levels in pregnant women with haemoglobin of more than 10 g/dl did not differ significantly from the corresponding mean observed in non-pregnant subjects. It seems that in normal pregnancy, the fall in erythrocyte vitamin B₁₂ is much less marked than the fall in plasma levels of this vitamin.