Correlation between Total Plasma Homocysteine Levels and Oxidative DNA Damage in Healthy Indian Adults

Introduction: Association of serum folate, Vitamin B-6 and B-12 deficiencies with hyperhomocysteinemia are well-documented. Several studies on Indian population, address the association of hyperhomocysteinemia with numerous diseases, but population-specific baseline levels of homocysteine in healthy population have not been elucidated till date. Aim: To establish Indian-population specific reference ranges for total plasma homocysteine in healthy adults in accordance to variation in dietary factors, serum B12 and folate status. The study also aimed to assess the contribution of cofactors in modulating homocysteine levels, and to evaluate the impact of higher homocysteine levels on the oxidative DNA damage. Materials and Methods: In this retrospective study, 151 apparently healthy non-diabetic, non-hypertensive individuals with normal thyroid, renal and cardiac function were recruited. Vitamin B-12, Folate, and Homocysteine assays were performed on ADVIA Centaur (R) XP Immunoassay system. Plasma 8-oxo-2deoxyguanosine levels were estimated by using commercially available ELISA kit. Student's t-test, ANOVA, Spearman rank correlation was used to establish the associations between variables. The p<0.05 was considered statistically significant. Results: The data was stratified according to age (Group 1: <= 45 yr, n=58 and Group 2: >45 yr, n=93) and gender. In both the age groups, homocysteine and 8-oxo-2deoxyguanosine levels were found to be elevated in men (p=0.003) while no gender-specific differences were observed in the levels of folate and B-12. Post-menopausal women had higher oxidative DNA damage as compared to the pre-menopausal women. Positive correlation was observed between total plasma homocysteine and plasma 8-oxo-2deoxyguanosine (r=0.35, p.0.03). An inverse correlation was observed between plasma B-12 levels and total plasma homocysteine in men (r=-0.24, p=0.02) while no such correlation was observed in women (r=0.22, p=0.10). No significant correlation was observed between plasma folate levels and total plasma homocysteine in both genders (male: r=-0.10, p=0.33; female: r=-0.23, p=0.09). Non-vegetarians had higher plasma B-12 levels (p<0.05) and lower homocysteine levels (p=0.03) than vegetarians. Conclusion: Healthy Indian adults have higher homocysteine levels than their counterparts due to vegetarian diet resulting in B-12 deficiency. A positive correlation was observed between total plasma homocysteine and oxidative DNA damage. Higher oxidative DNA damage was observed in post-menopausal women than pre-menopausal women, which might predispose them to many multifactorial disorders.