Plasma homocysteine concentrations and risk of coronary heart disease in UK Indian Asian and European men

Background Reasons for the increase in mortality due to coronary heart dise ase (CHD) in UK Indian Asians are not well understood. In this study, we te sted the hypotheses that elevated plasma homocysteine concentrations are a risk factor for CHD in Indian Asians, and explain part of their increased C HD risk, compared with Europeans. Methods We undertook two parallel case-control studies, one in Europeans an d one in Indian Asians. We recruited 551 male cases (294 European, 257 Indi an Asian) and 1025 healthy male controls (507 European, 518 Indian Asian). Fasting and post-methionine load homocysteine, vitamin B-12 and folate conc entrations, and conventional CHD risk factors were measured, Findings Fasting homocysteine concentrations were 8% higher (95% CI 3-14) i n cases compared with controls, in both ethnic groups. The odds ratio of CH D for a 5 mu mol/L increment in fasting plasma homocysteine was 1.3 (1.1-1. 6) in Europeans and 1.2 (1.0-1.4) in Indian Asians. The association between fasting plasma homocysteine and CHD was independent of conventional CHD ri sk factors in both ethnic groups. Post-load homocysteine concentrations wer e not significantly different in cases compared with controls. Among the co ntrols, fasting homocysteine concentrations were 6% (2-10) higher in Indian Asians than in Europeans. From the results we estimate that elevated homoc ysteine may contribute to twice as many CHD deaths in Indian Asians, compar ed with Europeans. The differences in homocysteine concentrations between t he two ethnic groups were explained by lower vitamin B-12 and folate levels in Asians. Interpretation Plasma homocysteine is a novel and independent risk factor f or CHD in Indian Asians, and may contribute to their increased CHD risk, Ra ised homocysteine concentrations in Indian Asians may be related to their r educed vitamin B-12 and folate levels, implying that the increased CHD risk in this group may be reduced by dietary vitamin supplementation.