Abstract
BACKGROUND: Dairy food intake has been associated with infertility; however, little is known with regard to associations with reproductive hormones or anovulation. OBJECTIVE: We investigated whether intakes of dairy foods and specific nutrients were associated with reproductive hormone concentrations across the cycle and the risk of sporadic anovulation among healthy women. METHODS: We prospectively measured serum reproductive hormones ≤8 times/menstrual cycle for 2 cycles from 259 regularly menstruating women (mean age: 27.3 y). Dairy food intake was assessed via 24-h dietary recalls 4 times/cycle. Dairy food intakes were assessed by 1) total and low- and high-fat dairy products; 2) dairy nutrients, including fat, lactose, calcium, and phosphorus; and 3) dairy foods, including milk, cheese, butter, cream, yogurt, and ice cream categories. Weighted linear mixed models were used to evaluate associations between dairy nutrients or food intakes and hormone concentrations. Modified Poisson regression models with robust error variance were used to evaluate anovulation. Models were adjusted for age, body mass index, race, physical activity, Mediterranean diet score, total energy, protein, fiber, caffeine, and other hormones. RESULTS: Each serving increase in total and low- and high-fat dairy foods and all increases in amounts of all dairy nutrients tested were associated with an ∼5% reduction in serum estradiol concentrations but were not associated with anovulation. Total and high-fat dairy food intakes were positively associated with serum luteinizing hormone concentrations. We observed associations between intakes of >0 servings of yogurt (RR: 2.1; 95% CI: 1.2, 3.7) and cream (RR: 1.8; 95% CI: 1.0, 3.2) and a higher risk of sporadic anovulation compared with no intake. CONCLUSIONS: Our study showed associations between increasing dairy food and nutrient intakes and decreasing estradiol concentrations as well as between cream and yogurt intakes and the risk of sporadic anovulation. These results highlight the potential role of dairy in reproductive function in healthy women.