Diet, serum insulin-like growth factor-I and IGF-binding protein-3 in European women

Objective: The aim of this study was to examine the relationship of diet with serum insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in women. Design: Cross-sectional study. Setting and subjects: The population are 2109 women who were control subjects in a case-control study of breast cancer nested in the European Prospective Investigation into Cancer and Nutrition. Control subjects were randomly chosen among risk sets consisting of female cohort members alive and free of cancer (except non-melanoma skin cancer) at the time of diagnosis of the index case. Matching criteria were age at enrolment, follow-up time, time of the day of blood collection and study centre. Diet was measured through validated questionnaires. Serum hormone concentrations were measured by enzyme-linked immunosorbent assays. The relationship between serum IGF-I, IGFBP-3, and intake of nutrients and foods was explored by linear regression in models adjusted for energy intake, age, body mass index, smoking, physical activity, centre and laboratory batch. Results: Serum IGF-I levels were positively related to protein intake (P-trend < 0.001), but not related to energy, fat or carbohydrate intake. Positive relationships were observed with the intake of milk (P-trend = 0.007), calcium (P-trend < 0.001), magnesium (P-trend = 0.003), phosphorus (P-trend < 0.001), potassium (P-trend = 0.002), vitamin B6 (P-trend = 0.03), vitamin B2 (P-trend = 0.001) and inverse relationships with vegetables (P-trend = 0.02) and beta-carotene (P-trend = 0.02). IGFBP-3 was not related with most of the nutrients and foods in this study. Conclusions: In this population, circulating IGF-I is modestly related with the intake of protein and minerals, and with milk and cheese, while IGFBP-3 does not appear to be related with diet.