Dietary fatty acid intakes and the risk of ovulatory infertility.

BACKGROUND: Pharmacologic activation of the peroxisome proliferator-activated receptor gamma (PPAR-gamma) improves ovulatory function in women with polycystic ovary syndrome, and specific dietary fatty acids can affect PPAR-gamma activity.

OBJECTIVE: The objective of the study was to assess whether the intakes of total fat, cholesterol, and major types of fatty acids affect the risk of ovulatory infertility.

DESIGN: We conducted a prospective cohort study of 18 555 married, premenopausal women without a history of infertility who attempted a pregnancy or became pregnant between 1991 and 1999. Diet was assessed twice during follow-up by using a food-frequency questionnaire.

RESULTS: During follow-up, 438 incidents of ovulatory infertility were reported. In logistic regression analyses, intakes of total fat, cholesterol, and most types of fatty acids were not related to ovulatory infertility. Each 2% increase in the intake of energy from trans unsaturated fats, as opposed to that from carbohydrates, was associated with a 73% greater risk of ovulatory infertility after adjustment for known and suspected risk factors for this condition [relative risk (RR) = 1.73; 95% CI: 1.09, 2.73]. Obtaining 2% of energy intake from trans fats rather than from n-6 polyunsaturated fats was associated with a similar increase in the risk of ovulatory infertility (RR = 1.79; 95% CI: 1.11, 2.89). In addition, obtaining 2% of energy from trans fats rather than from monounsaturated fats was associated with a more than doubled risk of ovulatory infertility (RR = 2.31; 95% CI: 1.09, 4.87).

CONCLUSION: trans Unsaturated fats may increase the risk of ovulatory infertility when consumed instead of carbohydrates or unsaturated fats commonly found in nonhydrogenated vegetable oils.