Validation of a Food Frequency Questionnaire for Bone Nutrients in Pregnant Women

Purpose: The aim was to validate a food frequency questionnaire (FFQ) against a 3-day food record (3DFR) for pregnant women with a focus on nutrients important for bone health from food and supplements. Methods: The FFQ and 3DFR were administered to pregnant women (n = 42) aged 18-45 years in their third trimester of pregnancy in Hamilton, Ontario. Nutrient analysis of intakes was conducted using an FFQ calculator and Nutritionist-Pro software. The average daily serving consumption of Milk and alternatives group and Vegetable subgroup from Canada's Food Guide were also compared. Results: There was a high positive correlation between methods for total dietary vitamin D (r = 0.83). Low positive associations were observed for total protein (r = 0.37), calcium (r = 0.36), vitamin K (r = 0.41), and servings of Milk and alternatives (r = 0.36). A cross-classification analysis using participants' intake quartiles revealed no major misclassifications. Bland-Altman analysis showed that the FFQ mildly underestimated the intake for protein, whereas it grossly overestimated the intake of vitamin K, and daily servings of Milk and alternatives and Vegetable. Conclusions: This FFQ can serve as a useful tool in clinical and research settings to assess key bone nutrients from foods and supplement sources in pregnant women.