The second most prevalent cancer among American women, breast cancer affects approximately one in eight women, according to the American Cancer Society. Research conducted over the past decade suggests that vitamins and diet may modify breast cancer risk. While as of 2011 the evidence is mixed as to whether vitamins B6 and B12 play a protective role in breast health, observational studies highlight possible linkages between low nutrient intake and increased risk.
Breast Cancer
With significant improvements in breast cancer screening, treatment and public health measures, rates of breast cancer incidence and mortality have declined steadily since the 1990s. However, invasive breast cancer continues to affect approximately 12 percent of the female population, and according to the Centers for Disease Control and prevention, 202,964 women were diagnosed with breast cancer in 2007 alone -- the most recent year for which statistics are available. Breast cancer risk has been linked to family history, environmental toxins, smoking, reproductive activity, hormone replacement therapy, obesity and age. While firm connections between breast cancer and nutrition have not been established, the CDC notes that investigators are currently examining the relationship between risk and diet, including the intake of vitamins B6 and B12.
Vitamin B6
B6 is an essential nutrient required by your body for red blood cell formation and the healthy functioning of the immune and nervous systems. B6 occurs naturally in a variety of food sources, including meat, fish, poultry, beans and legume, and certain fruits and vegetables, such as potatoes, bananas, avocados, spinach and tomatoes. The standards established by the Institute of Medicine recommend that adult women intake a minimum of 1.3 mg of B6 per day, but advise that daily consumption not exceed 100 mg, as excessive amounts can result in nerve damage.
B6 and Breast Cancer
Existing research on the association between B6 and breast cancer is conflicting. A prospective study of 195 breast cancer cases and matched controls published in March 1999 in "Cancer Epidemiology, Biomarkers and Prevention" found no connection between B6 intake and cancer incidence. However, a March 2003 article appearing in the "Journal of the National Cancer Institute" reports that higher intake of B6 may reduce breast cancer risk.
Vitamin B12
Vitamin B12, or cobalamin, is essential to red blood cell formation, oxygen delivery, neurological function and DNA synthesis. B12 also plays a central role in hormone regulation and fat and protein metabolism. B12 derives from animal products, such as meat, fish, poultry and diary, though is frequently added to fortify commercial grains and breakfast cereals. The Institute of Medicine standards recommend that adult women consume at least 2.4 mcg of B12 per day, and because of the nutrient's low toxicity, no upper limit has been set for daily intake.
B12 and Breast Cancer
Although findings from the 1999 prospective study indicated no linkages between B6 status and breast cancer, the researchers did find that women with the lowest levels of B12 had the greatest cancer risk. This evidence suggests that B12 may be protective against developing breast cancer, and that deficiencies may increase the likelihood of occurrence. A case control study of 475 Mexican women published in March 2006 in "Cancer Epidemiology, Biomarkers and Prevention" similarly found evidence for B12 serving as a protective factor, and noted that women with a high B12 intake had a decreased breast cancer risk.
References
- American Cancer Society: Breast Cancer
- Centers for Disease Control and Prevention: Breast cancer Statistics
- National Institutes of Health Office of Dietary Supplements: Vitamin B6
- "Cancer Epidemiology, Biomarkers and Prevention"; A Prospective Study on Folate, B12 and Pyridoxal 5-Phosphate and Breast Cancer; K. Wu et al.; March 1999
- "Journal of the National Cancer Institute"; Plasma Folate, Vitamin B6, Vitamin B12, Homocysteine, and Risk of Breast cancer; S.M. Zhang et al.; March 2003
- National Institutes of Health Office of Dietary Supplements: Vitamin B12
