FAMILIAL CORRELATION OF DIETARY INTAKES AMONG POSTMENOPAUSAL WOMEN

A positive family history is a risk factor for many chronic diseases, including most cancers, coronary heart disease, and diabetes. Since di et is also associated with most chronic diseases, one possible explana tion for non-Mendelian familial clustering is shared eating habits. Fo od frequency data were obtained on 3,515 sisters in the Iowa Women's H ealth Study, a prospective cohort of postmenopausal women. Intraclass correlations between sisters were computed on a range of energy-adjust ed nutrients to determine whether dietary intakes were more similar am ong siblings than among unrelated individuals. Two methods were used t o calculate correlations: analysis of variance modeling and weighted s ibling correlations. F-tests and randomization tests were used to dete rmine statistical significance. The intraclass correlations for all of the nutrients examined were statistically significantly greater than the hypothesized value of zero (P < 0.05). Representative correlations include dietary fiber (0.15), animal fat (0.12), vegetable fat (0.13) , calcium (0.14), iron (0.04), cholesterol (0.08), sodium (0.10), vita min D (0.16), and total energy intake (0.11). When corrected for measu rement error, the magnitude of these correlations increased, on averag e 62%. Although modest in magnitude, these correlations may be high en ough to influence familial clustering of complex diseases that are att ributed, in part, to diet. (C) 1998 Wiley-Liss, Inc.