Up to 10 percent of breast cancer cases are caused by mutations in tumor suppressor genes, including breast cancer susceptibility gene-1 (BRCA1) and breast cancer susceptibility gene-2 (BRCA2). Proteins made by these genes are used to repair damaged DNA. Defects in this process cause mutation carriers to have high lifetime risks of developing breast, ovarian and some other cancers.
One study foud that BRCA1 carriers in Poland had far lower rates of breast cancer than BRCA1 carriers in North America, indicating that the increased risks associated with BRCA mutations might be modified by lifestyle factors, including nutrition. Medium intensity physical activity has been found to be associated with a modest reduction in breast cancer risk for BRCA1 and BRCA2 carriers. In addition, there are some foods that have been found to protect against breast cancer in BRCA1 and/or BRCA2 carriers. BRCA1 and BRCA2 carriers diagnosed with breast cancer can also refer to our articles concerning their breast cancer subtypes (e.g. triple negative, ER+/PR+) for additional advice on what to eat.
Foods that reduce the risk of breast cancer in BRCA1 and BRCA2 carriers
The following foods have been found to be associated with reduced risk of breast cancer in BRCA1 and/or BRCA2 carriers or are rich sources of compounds that have been found to influence BRCA1 and/or BRCA2 expression in a favorable way:
There is also some evidence that maintaining optimal levels of vitamin D could reduce the risk of triple negative breast cancer among BRCA1 carriers. In addition, young women in general and BRCA1 mutation carriers in particular should avoid iron deficiency, since it has been linked to higher risk of breast cancer in these populations. However, one 2013 Korean study suggested that meat consumption preferentially increased breast cancer risk in BRCA2 carriers. Another study reported that consumption of flame-broiled fish was associated with increased risk of breast cancer in BRCA mutation carriers through its heterocyclic amine (HCA) content.
Several studies have found that heavy coffee consumption is associated with significantly reduced breast cancer risk among women with BRCA1 or BRCA2 gene mutations. However, a 2013 study reported that increased breast cancer risk was found for BRCA1 mutation carriers who were heavy coffee drinkers. The relationship between alcohol and breast cancer risk in BRCA mutation carriers is unclear because not all studies have reported a harmful effect of alcohol consumption. However, one compelling 2015 study reported that embryos with BRCA1 deficiencies were particularly susceptible to the carcinogenic effects of alcohol in an animal model of breast cancer.
Foods that reduce the risk of ovarian cancer
The following foods have been found to be associated with lower risks of both ovarian cancer and breast cancer:
Foods that increase the risk of ovarian cancer
The following foods have been found to increase the risks of both ovarian cancer and breast cancer:
- Bread, white
- Cured and salted meats
- Fish contaminated with PCBs
- Milk, including low-fat
- Salted fish
- Salted shrimp paste
- Soybean paste
While supplements containing I3C, DIM, resveratrol, and genistein (all protective against BRCA-associated breast cancer) are readily available, the safer and healthier strategy is to consume foods that contain these substances. Safe and effective dosages have not been determined for the supplements and there is some evidence that taking them could backfire, actually promoting breast cancer or other cancers. One 2016 study reported that high circulating levels of folate was associated with increased risk of breast cancer in BRCA 1 and BRCA 2 mutation carriers, suggesting that folic acid supplements could be harmful.
Bisphenol A (BPA) exposure
Bisphenol A (BPA), an endocrine disruptor, is suspected of increasing the risk of breast cancer. BPA has been found to stimulate mammary cell proliferation in BRCA1 mutant mice, leading to hyperplasia. This suggests that women with BRCA1 mutations might be particularly vulnerable to the cancer promoting effects of BPA. BPA exposure can be limited by avoiding canned foods, canned sodas, and polycarbonate plastic bottles and food containers, which may be marked with a 7 or 3 recycling number in a triangle-shaped icon (normally found on the base).
Antiperspirants containing aluminum compounds
Most antiperspirant sprays, sticks, and roll-ons contain aluminum chlorohydrate or other aluminum salts designed to block the secretion of sweat. The aluminum in such preparations has been shown to enter through the skin in tiny amounts and to accumulate in breast tissue. Applying an antiperspirant to skin that is scraped, cut or irritated (such as may occur after shaving) can result in significantly higher exposures. Aluminum has been demonstrated to cause DNA damage and to induce inflammatory responses within the breast. Aluminum salts found in antiperspirants were also shown in one study to reduce level of BRCA1 mRNA and BRCA1 protein in normal breast epithelial cells. Levels of BRCA2 and other tumor suppressor genes (CHK1, CHK2, Rad51, and ATR) were also reduced. Given that aluminum appears to interfere with the functioning of tumor suppressor genes, BRCA mutation carriers should probably entirely avoid using aluminum-containing antiperspirants and deodorants.
Eat a wide variety of foods
It is important for BRCA1 and BRCA2 mutation carriers to eat a wide variety of the foods from our recommended food list and limit or avoid those on our avoid list, in addition to paying particular attention to the foods on the lists above. Please see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.
Below are links to recent studies on this topic. For a more complete list of studies, please click on BRCA1 and BRCA2.