Association of diet with serum insulin-like growth factor I in middleaged and elderly men

Background: Insulin-like growth factor I (IGF-I) has been implicated in several chronic diseases, including cancer, heart disease, and osteoporosis. Objective: Our aim was to assess whether intakes of total energy, alcohol, vitamins, minerals, and foods rich in protein and minerals (including red meat, fish and seafood, poultry, and milk) are associated with serum IGF-I concentrations in middle-aged and elderly men. Design: We measured serum IdF-I concentrations in 226 free-living healthy men aged 42-76 y. The average of fourteen 24-h dietary telephone interviews performed over 1 y was used to estimate long-term dietary intake. Results: We observed statistically significant positive associations between intakes of protein (P for trend = 0.001) and zinc (P for trend = 0.002) and serum IGF-I concentrations after adjusting for age. The difference in mean IGF-I concentrations for the highest compared with the lowest quintile of intake was approximate to 17% (162 mu g/L compared with 139 mu g/L) for protein and approximate to 16% (166 mu g/L compared with 143 mu g/L) for zinc. Consumption of red meat (P for trend = 0.05) and fish and seafood (P for trend = 0.07) was modestly positively associated with IGF-I concentrations. Other dietary factors were not associated with IGF-I concentrations. Conclusion: In this population of healthy well-nourished men, greater dietary intakes of protein, zinc, red meat, and fish and seafood were associated with higher IGF-I concentrations.