Vitamins, selenium, iron, and coronary heart disease risk in Indians, Malays, and Chinese in Singapore

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Abstract
STUDY OBJECTIVE: To examine the hypothesis that the higher rates of coronary heart disease (CHD) in Indians (South Asians) compared with Malays and Chinese is partly because of differences in antioxidants (vitamins A, C, and E, and selenium) and pro-oxidants (iron). DESIGN: Cross sectional study of the general population. SETTING: Singapore. PARTICIPANTS: Random sample of 941 persons aged 30 to 69 years. MAIN RESULTS: There were moderate correlations between vitamin A and vitamin E, and between these vitamins and selenium. Mean plasma vitamins A and E were similar by ethnic group. Vitamin A concentration for Indians were (men 0.66 and women 0.51 mg/l), Malays (men 0.67 and women 0.54 mg/l), and Chinese (men 0.68 and women 0.52 mg/l). Vitamin E concentrations for Indians were (men 12.9 and women 12.8 mg/l), Malays (men 13.6 and women 13.3 mg/l), and Chinese (men 12.6 and women 12.6 mg/l). In contrast, mean plasma vitamin C concentrations were lower in Indians (men 5.7 and women 6.9 mg/l) and Malays (men 5.1 and women 6.4 mg/l) than Chinese (men 6.3 and women 8.4 mg/l). Mean serum selenium was lower in Indians (men 117 and women 115 micrograms/l) than Malays (men 122 and women 122 micrograms/l) and Chinese (men 126 and women 119 micrograms/l). Mean serum ferritin was much lower in Indians (men 132 and women 50 micrograms/l) than Malays (men 175 and women 85 micrograms/l) and Chinese (men 236 and women 92 micrograms/l). MAIN CONCLUSIONS: Lower vitamin C and selenium in Indians, particularly in combination, could play a part in their increased risk of CHD. Vitamins A and E, and ferritin (iron) have no such role. Lower vitamin C in Indians and Malays is probably because of its destruction by more prolonged cooking. In Indians, lower selenium is probably because of a lower dietary intake and the much lower ferritin to a lower dietary intake of iron and its binding by phytates.