Elevated Serum B12 and Increased Risk of Disease

Summary: Two studies have shown an increased risk of coronary heart disease (CHD) or mortality in subjects with elevated serum B12. Pancharuniti et al. (1) found an increased risk of CHD that barely reached statistical significance. Zeitlin et al. (2) found (what equaled) an increased risk of death of 7% for every 100 pg/ml increase in serum B12. Both of these findings were probably due to B12 being a marker for foods associated with heart disease and not that B12 itself was damaging. As reported throughout this article, most studies have shown B12 levels on the higher end of normal to be healthy.

Pancharuniti et al. (1996) performed a retrospective study in which serum B12 levels did not differ significantly between those with coronary artery disease (CAD) and matched controls. However after controlling for homocysteine levels and other CAD risk factors, there was a barely significant association between serum B12 and increased risk of CHD (rr = 1.5; CI: 1.0, 1.8). The authors thought this could be due to the fact that B12 is found in foods that increase one's risk of heart disease such as red meats.

Zeitlin et al. (1997) followed 488 people aged 75-85 for an average of 6 years. Average B12 levels were 515 pg/ml. In measuring death, stroke, heart attack, coronary heart disease, and cardiovascular disease events, there was no significant difference in serum B12 between those who did (569 ± 479 pg/ml) and did not (491 ± 267 pg/ml) have an event. However, each increase of 1 pg/ml in serum B12 was associated with a .07% increase in risk of death (P = .041). This means that someone with a 100 pg/ml higher serum B12 had a 7% higher risk of death. Zeitlin et al. suggest that the higher risk of death could be because B12 is a marker for animal product intake, and not from B12 itself. But, they also speculate that high B12 stores could cause liver damage, contributing to death. This is purely conjecture as there are no reports of liver toxicity due to high B12 stores.


1. Pancharuniti N, Lewis CA, Sauberlich HE, Perkins LL, Go RC, Alvarez JO, Macaluso M, Acton RT, Copeland RB, Cousins AL, et al. Plasma homocyst(e)ine, folate, and vitamin B-12 concentrations and risk for early-onset coronary artery disease. Am J Clin Nutr. 1994 Apr;59(4):940-8. Erratum in: Am J Clin Nutr. 1996 Apr;63(4):609.

2. Zeitlin A, Frishman WH, Chang CJ. The association of vitamin b 12 and folate blood levels with mortality and cardiovascular morbidity incidence in the old old: the Bronx aging study. American Journal of Therapeutics. 1997 Jul-Aug;4(7-8):275-81.