A 20% reduction in breast cancer risk was observed by researchers among women that used vitamin E supplements and had a low dietary intake of vitamin E. Researchers also noted a 20% risk reduction in breast cancer risk in women who used supplemental vitamin B and had low dietary vitamin B intake.
The Shanghai Breast Cancer Study was conducted in Shanghai, China from 1996-1998 (Phase I) and 2002-2004 (Phase II). Study participants in phase I were aged 25 to 64 years old and in phase II 20 to 70 years old. It was a large population-based, case control study with 3,454 incident breast cancer cases and 3,474 controls. Researchers used unconditional logistic regression models to determine adjusted odds ratios for breast cancer risk associated with vitamin supplement use.
The researchers stated, "This study suggests that vitamin E and B supplements may confer protection against breast cancer among women who have low dietary intake of those vitamins."
Dorjgochoo, T., et al. "Vitamin Supplement Use and Risk for Breast Cancer: the Shanghai Breast Cancer Study" Breast Cancer Res. Treat., 2007, Oct. 5; [Epub ahead of print].