Abstract
BACKGROUND: Choline and betaine, similar to folate, are nutrients involved in one-carbon metabolism and hypothesised to reduce breast cancer risk. No prospective study among post-menopausal women has examined choline and betaine intakes in relation to breast cancer risk. METHODS: We examined the intake of choline and betaine and breast cancer risk among 74 584 post-menopausal women in the Nurses' Health Study. Nutrient intake was assessed using a validated food-frequency questionnaire six times since 1984. During 20 years of follow-up from 1984 until 2004, we documented 3990 incident cases of invasive breast cancer. RESULTS: Overall, choline (mean+/-s.d.; 326+/-61 mg per day) and betaine (104+/-33 mg per day) intake was not associated with a reduced risk of post-menopausal breast cancer. Participants in the highest quintile of intakes had multivariate relative risks of 1.10 (95% confidence interval (95% CI): 0.99-1.22; P-value, test for trend=0.14) for choline and 0.98 (95% CI: 0.89-1.09; P-value, test for trend=0.96) for betaine, compared with those in the lowest quintiles of intakes. The results were similar in breast cancer stratified by hormone receptor (oestrogen receptor/progesterone receptor) status. The association between choline intake and breast cancer risk did not differ appreciably by alcohol intake (non-drinker, <15 or 15+ g per day) or several other breast cancer risk factors, including family history of breast cancer, history of benign breast disease, body mass index, post-menopausal hormone use, and folate intake. CONCLUSION: We found no evidence that higher intakes of choline and betaine reduce risk of breast cancer among post-menopausal women.