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.
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 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:
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.

Beneficial supplements for BRCA mutation carriers

There is no supplement or combination of supplements that has been shown conclusively to reduce the risk of breast cancer recurrence. Attempting to take advantage of the apparent treatment effects of micronutrients and other dietary components by using supplements carries the risk of adverse and paradoxical effects, including promoting breast cancer growth and metastasis.
What is known is that when a beneficial micronutrient is administered at low doses by consuming food, it is likely to have subtle chemopreventive effects, whereas when the same micronutrient is administered at high doses, it is more likely to have pharmacological effects, with mostly unknown results. It is best to obtain beneficial compounds by consuming food, if possible. Supplements should be used if medically necessary or to make up for deficiencies that are difficult to correct through diet.
The following supplements generally have been found to be safe and beneficial for carriers of harmful BRCA mutations:
CoQ10 (if needed for heart health)100 to 400 mg/day
Fish oil (from wild-caught fish)1000 to 2000 mg/day
Vitamin D1000 to 2000 IU/day
Avoid taking supplements during the two days before, the day of, and the day after any chemotherapy treatment. Please consult your oncology team for advice concerning your situation and dosages.
There is some specific evidence that maintaining optimal levels of vitamin D could reduce the risk of triple negative breast cancer among BRCA1 carriers. It might make sense to be tested for deficiency in vitamin D and plan for follow up to determine if your reading has reached a desirable level.
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 Korean study suggested that meat consumption preferentially increased breast cancer risk in BRCA2 carriers.

Foods to limit or avoid for BRCA mutation carriers

One 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. Another 2020 study reported that consuming reheated cooking oil intensifies harmful BRCA1 mutations, apparently since repeated heating of oils produces reactive toxic intermediates that can lead to such mutations. This suggests that restaurant foods such as French fries that are cooked in oil that is used for many hours over a period of days should be avoided. Milk has also been linked to increased breast cancer risk in BRCA1 carriers.
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. Smoking during the pre-reproductive years appears to increase breast cancer risk for harmful BRCA mutation carriers.

Supplements to be avoided by BRCA mutation carriers

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 these compounds.
A 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. On the other hand, a 2019 study reported that folic acid and/or vitamin B12 supplement use was associated with reduced risk of breast cancer for BRCA 1 carriers.

Foods that reduce 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 risk of ovarian cancer

The following foods have been found to increase the risks of both ovarian cancer and breast cancer:

Additional comments

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.