Marked Gender Difference in Plasma Total Homocysteine Concentrations in Indian Adults with low Vitamin B₁₂

Context: Plasma total homocysteine (tHcy) is higher in men than women. Objective: To explore the gender differences in tHcy in relation to determinants of one-carbon metabolism in Indian people with low B₁₂ and adequate folate. Setting: The study took place in rural and urban areas of Pune, India. Design and participants: Participants were 441 men from the cross-sectional Coronary Risk of Insulin Sensitivity in Indian Subjects study (CRISIS) and premenopausal wives of 146 men (median ages 38 and 34 years, respectively). Main outcome measures: Gender difference in fasting tHcy in relation to plasma albumin and creatinine concentrations, lifestyle factors, diet and lean mass, plasma B12 and red cell folate (RCF) was assessed. Results: Prevalence of high tHcy (> 15 µmol/L, median 14.4 µM) was 40 %, low B12 (< 150 pmol/L, 114 pmol/L) 66 %, and low RCF (< 283 nmol/L, 525 nmol/L) 8 %. Men had higher (1.8x) plasma tHcy concentrations (16.2 µmol/L) than women (9.5 µmol/L). Only 50 % of the gender difference was explained by age, lean mass, B12, and RCF. The difference remained after controlling for other explanatory variables. Women with a tHcy of 9.3 µM had the same B12 concentration (129 pmol/L) as men with a tHcy of 15 µM; and for a tHcy of 10.0 µmol/L women had the same RCF concentration (533 nmol/L) as men with a tHcy of 15 µmol/L. Conclusions: Adult Indian women have markedly lower tHcy concentrations compared to men. This suggests a lower threshold for supplementation to improve reproductive and cardiovascular outcomes.