Epidemiologic study of trace elements and magnesium on risk of coronary artery disease in rural and urban Indian populations.

OBJECTIVE: To determine the association of trace elements and magnesium with risk of coronary artery disease (CAD) in rural and urban populations of India. DESIGN AND SETTING: Cross-sectional surveys on the randomly selected municipal streets in Moradabad city and one village in Moradabad tahsil in North India. SUBJECTS AND METHODS: There were 162 rural (86 men and 96 women) and 152 urban (80 men and 72 women) subjects between 26 to 65 years of age. Evaluations were obtained by physician- and dietitian-administered, validated questionnaires, physical examination, electrocardiogram and blood examination. RESULTS: The prevalence of CAD and coronary risk factors was 2.5 times higher in the urban population compared to rural subjects (8.6 vs. 3.0%). In rural subjects, dietary intakes and plasma levels of vitamins and minerals were comparable with those of urban subjects except for higher dietary intake of magnesium in rural subjects and higher plasma vitamin A level in urban subjects. In both rural and urban subjects, low serum zinc (80 +/- 82 vs. 110 +/- 11.0 micrograms/dl, p < 0.05) and magnesium levels (1.60 +/- 0.36 vs. 1.71 +/- 0.41 mEQ/L, p < 0.05) and lower zinc/copper ratio (0.58 +/- 0.08 vs. 1.11 +/- 0.25 p < 0.50) were inversely associated with CAD. Serum levels of copper and iron were significantly higher and plasma levels of antioxidant vitamins A, E and C and beta-carotene were significantly lower in patients with CAD compared to the rest of the subjects. In both rural (7.1 +/- 1.2 mg/day) and urban subjects (8.6 +/- 1.6 mg/day), zinc consumption was half of the recommended dietary allowances. Higher prevalence of CAD in urban compared to rural subjects was attributed to higher dietary fat intake and higher prevalence of risk factors in urban subjects. CONCLUSIONS: The findings suggest that lower serum levels of zinc and magnesium and lower zinc copper ratio were inversely associated with CAD. It is possible that urban populations with higher risk of CAD may benefit by decreasing dietary fat intake and by increasing their intake of foods rich in zinc and magnesium.