Bioenrichment of Vitamin B12 in Fermented Foods

We studied a six-month-old infant with severe megaloblastic anemia, coma and hyperpigmentation of the extremities. He was found to have methylmalonic aciduria (79 mumol per milligram of creatinine) and homocystinuria (0.85 mumol per milligram of creatinine). Additional biochemical abnormalities included cystathioninuria, glycinuria, methylcitric aciduria, 3-hydroxypropionic aciduria and formic aciduria. The concentration of vitamin B12 in the serum was 20 pg per milliliter. This severe nutritional deficiency was a consequence of inadequate intake, for the infant was exclusively breast-fed by a strictly vegetarian mother who manifested methylmalonic aciduria. Our observations emphasize the importance of educating strict vegetarians about the deficiency of vitamin B12 in their diets and the importance of vitamin B12 supplementation.

When one stops eating vitamin B-12 (cobalamins), one passes through four stages of negative cobalamin balance: serum depletion [low holotranscobalamin II, ie, low vitamin B-12 on transcobalamin II (TCII)], cell depletion (decreasing holohaptocorrin and low red cell vitamin B-12 concentrations), biochemical deficiency (slowed DNA synthesis, elevated serum homocysteine and methylmalonate concentrations), and, finally, clinical deficiency (anemia). Serum vitamin B-12 is on two proteins: the circulating vitamin B-12 delivery protein, TCII, and the circulating vitamin B-12 storage protein, haptocorrin. Because TCII is depleted of vitamin B-12 within days after absorption stops, the best screening test for early negative vitamin B-12 balance is a measurement of vitamin B-12 on TCII (holoTCII). HoloTCII falls below the bottom of its normal range long before total serum vitamin B-12 (which is mainly vitamin B-12 on haptocorrin) falls below the bottom of its normal range.