Protein intake and the risk of premenstrual syndrome

OBJECTIVE: To examine the relationship between protein intake and the risk of incident premenstrual syndrome (PMS). DESIGN: Nested case-control study. FFQ were completed every 4 years during follow-up. Our main analysis assessed protein intake 2-4 years before PMS diagnosis (for cases) or reference year (for controls). Baseline (1991) protein intake was also assessed. SETTING: Nurses' Health Study II (NHS2), a large prospective cohort study of registered female nurses in the USA.ParticipantsParticipants were premenopausal women between the ages of 27 and 44 years (mean: 34 years), without diagnosis of PMS at baseline, without a history of cancer, endometriosis, infertility, irregular menstrual cycles or hysterectomy. Incident cases of PMS (n 1234) were identified by self-reported diagnosis during 14 years of follow-up and validated by questionnaire. Controls (n 2426) were women who did not report a diagnosis of PMS during follow-up and confirmed experiencing minimal premenstrual symptoms. RESULTS: In logistic regression models adjusting for smoking, BMI, B-vitamins and other factors, total protein intake was not associated with PMS development. For example, the OR for women with the highest intake of total protein 2-4 years before their reference year (median: 103·6 g/d) v. those with the lowest (median: 66·6 g/d) was 0·94 (95 % CI 0·70, 1·27). Additionally, intakes of specific protein sources and amino acids were not associated with PMS. Furthermore, results substituting carbohydrates and fats for protein were also null. CONCLUSIONS: Overall, protein consumption was not associated with risk of developing PMS.