Background: Later age at menopause is associated with a greater risk of breast cancer. Dietary factors may at least partially influence breast cancer risk through an effect on the age at menopause.
Objective: We studied the effect of a low-fat, high-carbohydrate (LFHC) dietary intervention on the timing of menopause in women with greater risk of breast cancer.
Design: The study population included participants from an LFHC dietary intervention trial for the prevention of breast cancer in women with extensive mammographic density, a strong risk factor for breast cancer. Women who were premenopausal at baseline (n = 2611) were followed for an average of 7 y for menopause. Survival analysis was used to compare the time to menopause between the LFHC and control groups and to assess other factors associated with age at menopause.
Results: The LFHC intervention did not affect the time to natural menopause overall (P = 0.72 for log-rank test comparing study groups; n = 699 events). An observed interaction between study group and baseline body mass index (BMI; P = 0.01) indicated that the intervention group experienced earlier menopause than did the control group when BMI was low and that a higher BMI was associated with later menopause in the intervention group only. Greater parity, weight, and education were associated with later menopause, and greater age at first birth and baseline smoking were associated with earlier menopause.
Conclusions: Overall, the LFHC dietary intervention did not influence the timing of menopause. Factors associated with age at menopause in this population were consistent with those reported in other populations.