The 204 participants in the 1996 study were predominantly male and averaged 48 years old. Thirty-eight percent consumed a vegetarian diet, and 17% of nonvegetarians ate animal products less than once a month. The investigators were interested not only in vitamin B-12 status, but in serum levels of methylmalonic acid (MMA) and homocysteine (tHcy), since B-12 is a cofactor in the metabolism of these two amino acids. Only 10% of the group had normal concentrations of vitamin B-12, MMA, and tHcy; 52% had low vitamin B-12 levels. Metabolic indications of B-12 deficiency were apparent in 76% of the subjects who had elevated tHcy, and in 73% who had high MMA.
Nonvegetarian subjects who reported regular consumption of eggs, poultry and mutton were often found to be vitamin B-12 deficient. The authors suggest the possibility that the Indian population may have adapted to chronic low vitamin B-12 concentrations through genetic mechanisms, and that persistent gastrointestinal infections may be affecting vitamin B-12 absorption. The elevated tHcy concentrations that occur with chronic, subclinical vitamin B-12 deficiency have been associated with cardiovascular disease, cancer, cognitive impairment, and birth defects, and could pose a significant health risk to the more than one billion Indian population. An accompanying editorial by Antony emphasizes the importance of distinguishing between combined folate and B-12 deficiency and B-12 deficiency alone, since both conditions share common serum indicators.
Refsum, Helga et al. Hyperhomocysteinemia and elevated methylmalonic acid indicate a high prevalence of cobalamin deficiency in Asian Indians. Am J Clin Nutr 2001;74:233-41.
Antony, Asok C. Prevalence of cobalamin and folate deficiencies in India--audi alteram partem. Am J Clin Nutr 2001;74:157-9.
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