Dietary sources, intake levels and determinants of soy isoflavones of Chinese midlife women in Hong Kong

Abstract

Purpose The dietary sources, intake levels and determinants of soy isoflavones intake were examined using 3217 dietary recalls collected from 145 Hong Kong Chinese women aged 50–61 years. Methods Multiple-pass 24-hour dietary recalls were phone-administered by trained interviewers on 23 random nonconsecutive days to all participants over a 12-month period from 2001 to 2002. Isoflavone intake was calculated using analytical values in the CU Soy Database. Results The median daily intake of total isoflavones was 6.3 mg (IQR 3.7–10.7) among the study population. Non-Cantonese women had a higher mean intake value of 8.1 mg (IQR 4.6–17.1) compared with 6.0 mg (IQR 3.5–10.3) among the Cantonese. Altogether, 22 foods contributed ∼90% of the total isoflavones intake. Soft tofu alone accounted for approximately 21% of the isoflavone intake, followed by beancurd skins (7.1%), name brand soybean milk (6.3%), homemade soybean milk (6.2%), and no name-brand soybean milk (5.8%). Combined, these five food items contributed 46% of the total isoflavones consumed in the diet. Multiple linear regression analysis indicated total isoflavones intake decreased nonlinearly with increasing age. Soy consumption was also negatively related to Cantonese, but positively related to self-rated health. Conclusion The data provided the foundation for the development of food frequency questionnaire that will be used to examine the effects of soy isoflavones on health in Asian women.