We assessed baseline diet in 1986 with a semi-quantitative FFQ developed by Harvard & modified slightly.

Daily intakes of nutrients were calculated by summing across all food items the product of the fq of consumption of the specified serving of each food by the nutrient content of that unit of food.

We also collected info on vitamin supplement use.

The validity and reproducibility of the FFQ was assessed in a subset of Iowa women and, although the correlation coefficient for protein in our cohort was somewhat low, it ranged from 0.44 to 0.47 in the Harvard cohorts when compared to a greater number of days of dietary recording than what we used.