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Folate and Breast Cancer: Does folate reduce the risk of breast cancer?

Clinical bottom line: for women who consume at least one alcoholic drink a day, folate supplementation probably protects against breast cancer.

The Nurses' Health Study showed that high folate intake is associated with reduced risk of colon cancer ( Bandolier 60 ). Information from the same study was used to examine the association between folate and risk of breast cancer, particularly among women who regularly consume alcohol.

Message

Overall, folate was not associated with reduced risk of breast cancer. However, women who regularly consumed at least one alcoholic drink a day reduced the risk of breast cancer with a high folate intake (from foods and multivitamin supplements). It is unlikely that foods alone provide enough folate, so a multivitamin supplement would be beneficial for women having at least one drink a day.

Study

In 1980, 88,818 women from the Nurses' Health Study, aged 34-59 years, completed questionnaires on their medical history, lifestyle and diet (including multivitamin supplement use). This information was updated regularly over 16 years. During this time 3,483 cases of breast cancer were documented.

Results

Allowances were made for many factors associated with breast cancer (eg. history of breast cancer in mother or a sister). Folate from foods alone was not associated with overall risk of breast cancer. A higher folate intake from foods and multivitamin use was also not associated with overall risk.

However, women who consumed at least 15 g/d of alcohol (about one drink a day), with a total folate intake of at least 600 µg/d (compared with 150 to 299 µg/d), reduced their risk of breast cancer by 45% (relative risk 0.55, 95% confidence interval 0.39 to 0.76). The risk remained essentially the same after allowing for other nutrients in multivitamin supplements.(12.8g ethanol for 360ml/12oz beer; 11.0g for 120ml/4oz wine; 14.0g shot of liquor 45ml/1.5oz, 80% proof).

Among women who consumed at least 15 g/d of alcohol, taking a multivitamin supplement reduced their risk by 26% compared with women not taking a supplement (relative risk 0.74, 95% confidence interval 0.59-0.93).

Comment

Bandolier has previously reported on the importance of folate in relation to colon cancer ( Bandolier 60 ) and indirectly heart disease, through homocysteine ( Bandolier 57 ). This study shows the association between folate and breast cancer among women having approximately just one drink a day. Folate from foods alone is unlikely to be sufficient. The message from these three reports is the same: eat properly; and take a multivitamin supplement to ensure a high folate intake.

Reference

S Zhang et al. A prospective study of folate intake and the risk of breast cancer. JAMA 1999 281: 1632-1637.