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Supplements & Breast Cancer Risk -- doctor holding pink breast cancer awareness ribbon


Although there is not enough evidence to support the use of a particular vitamin or supplement to directly reduce the risk of breast cancer, associations have been found between intake of certain foods and food-based nutrients - such as omega-3 fatty acids, extra virgin olive oil, vitamin C and others - and a reduced risk of breast cancer, as discussed below. At the same time, an increase in the risk of breast cancer has been identified with certain other foods and supplements, as discussed further below. Use the links for more details.

Supplements and foods associated with reduced breast cancer risk

Fish oil supplementation was associated with a reduced risk of breast cancer. Eating fish is associated with a lower risk of recurrence, and risk of death, from breast cancer and eating fish is associated with a lower risk of recurrence, and risk of death, from breast cancer. In women with early stage breast cancer, higher intakes of the omega-3 fatty acids DHA and EPA from fish have been associated with a 25% lower risk of breast cancer recurrence.

Maintaining a Mediterranean diet supplemented with extra virgin olive oil was associated with a lower risk of breast cancer compared to a low-fat diet, according to one study.

Women who eat a lot of soy early in life may have a lower risk of breast cancer, but it's not known whether soy supplements have a benefit (be aware that soy isoflavones may not be safe for women with estrogen-sensitive breast cancer).

Higher dietary intakes of choline have also been associated with a reduced risk of breast cancer. (However, choline intake may also trigger the creation of a compound, TMAO, that can increase the risk of cardiovascular disease.)

Similarly, preliminary research suggests that higher intakes of CLA (conjugated linoleic acid) from foods are associated with a reduced risk of breast cancer in postmenopausal women. [Note: This association is with foods with CLA, not supplements — which can potentially adversely affect the liver. Increased lutein intake has been associated with a reduced risk of breast cancer, and population studies suggest that vitamin A (both pre-formed and beta-carotene) may also reduce the risk, but studies are needed to investigate the effects of these nutrients when taken as supplements.

Population studies have found drinking green tea to be associated with a reduced risk of breast cancer recurrence, but studies have not been consistent regarding an overall effect on breast cancer risk.

Higher blood levels of vitamin D have been associated with higher overall survival rates among women with breast cancer.

A study among older women with invasive breast cancer found those who took a daily multivitamin were 30% less likely to die from the disease, compared to non-users, over a seven year period.

Supplements and foods associated with an increased risk of breast cancer risk

High intake of vitamin C from food was associated with a decreased risk of postmenopausal breast cancer in one study; however, the same study also found that women with a high intake of vitamin C from food who also took vitamin C supplements had an increased risk.

Cow's milk contains estrogens (lower amounts are found yogurt and cheese), as well as insulin-like growth factor-1 (IGF-1), hormones that can play a role in breast cancer development. Nevertheless, as noted by the National Breast Cancer Association, several studies did not find a link between the consumption of dairy or dairy milk (i.e., cow's milk) and the risk of breast cancer. However, in 2020, a large study that followed over 50,000 women (average age 57) in the U.S. and Canada for an average of eight years found that drinking 1/4 to 1/3 cup of dairy milk per day was associated with a 30% increase in the risk of developing breast cancer compared to drinking little or no milk. Drinking 1 cup of milk per day was associated with a 50% increase in risk, and drinking 2 to 3 cups per day was associated with a 70 to 80% increase in risk. The type of dairy milk (full fat, reduced, or nonfat) was not a factor. Intakes of cheese, yogurt, soy milk, or other soy products were not associated with breast cancer risk (Fraser, Int J Epidemiol 2020).

A note of caution: Be aware that it may be dangerous to use antioxidant supplements during chemotherapy and radiation therapy for breast cancer, as this has been associated with lower survival and higher recurrence rates.

See the American Cancer Society's website for more information about nutrition and cancer prevention, as well as other lifestyle factors which can be addressed, such as alcohol intake and bodyweight.

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September 11, 2021

Has anyone heard of the Chek 2 gene? It supposedly is a high risk for breast cancer also.

Dennis 21431
November 25, 2020

My wife had breast cancer. Her oncologist recommended she take 2000 IU of Vitamin D. Her blood count was 20 ng.

March 2, 2020

I'm wondering if organic or grass-fed cow's milk was considered in the above study. Cows from CAFO's (Concentrated Animal Feeding Operations - where 99% of our dairy comes from) are given hormones and antibiotics, which could contribute to breast cancer.
March 2, 2020

Hi Jeanette - That study was based on a tens of thousands of people in the U.S. and Canada, so the vast majority of the milk was likely not from grass-fed cow's milk.

March 1, 2020

Regarding the study of 50,000 women in the "Cow's milk" paragraph: what could account for the different outcome when milk is cultured (i.e., yogurt and cheese)?
The microbes to culture milk use up all or most of the sugar lactose I suppose, but does the study imply that the microbes metabolize and change the hormones or simply absorb them? That's all I can think of, but surely that would be mentioned or studied or something...?

Just yesterday I bought a gallon of milk to supplement the calcium supplements. Now I guess I'll turn all of it into yogurt rather than the half of it I had planned -- the same milk magically transformed from dangerous to harmless by probiotics. I wonder if anyone has ever added estradiol to probiotics just to see what happens. Of course estradiol's human; maybe acidophilus only goes for bovine hormones, who knows.

I'm grateful I don't need to give up yogurt and cheese! I love cheese!

Anyway I find the results weird (like many things in life) and I'm very curious if anyone here has a clue what happens to hormones with the culturing.

March 1, 2020

If participants in the studies on milk consumption and breast cancer were drinking conventional non-organic milk, it doesn't seem surprising that they would have increased risk of breast cancer. Conventionally produced milk comes from cows treated with recombinant bovine growth hormone, and this milk contains some RBGH along with traces of whatever pesticides were in what the cows were fed. The European Union refused for decades to take American milk containing RBGH, believing, on evidence, that it is a cancer risk. (They may still outlaw it, but am not sure; possibly they may have been pushed into allowing such milk to be sold there, through NAFTA or some other means.)

March 1, 2020

Total confusion about yogurt on my part now because of this recent article from Science Daily, below. Can you clarify. Should breast cancer survivors eat yogurt or not?

"One of the causes of breast cancer may be inflammation triggered by harmful bacteria say researchers.

Scientists say their idea- as yet unproven -- is supported by the available evidence, which is that bacterial induced inflammation is linked to cancer.

The paper in the journal Medical Hypotheses is by Lancaster University medical student Auday Marwaha, Professor Jim Morris from the University Hospitals of Morecambe Bay NHS Trust and Dr Rachael Rigby from Lancaster University's Faculty of Health and Medicine.

The researchers say that: "There is a simple, inexpensive potential preventive remedy; which is for women to consume natural yoghurt on a daily basis."

Yoghurt contains beneficial lactose fermenting bacteria commonly found in milk, similar to the bacteria -- or microflora- found in the breasts of mothers who have breastfed.

Dr Rigby said: "We now know that breast milk is not sterile and that lactation alters the microflora of the breast.

"Lactose fermenting bacteria are commonly found in milk and are likely to occupy the breast ducts of women during lactation and for an unknown period after lactation."

Their suggestion is that this lactose fermenting bacteria in the breast is protective because each year of breast feeding reduces the risk of breast cancer by 4.3%.

Several other studies have shown that the consumption of yoghurt is associated with a reduction in the risk of breast cancer, which the researchers suggest may be due to the displacement of harmful bacteria by beneficial bacteria.

The researchers conclude that: "The stem cells which divide to replenish the lining of the breast ducts are influenced by the microflora, and certain components of the microflora have been shown in other organs, such as the colon and stomach, to increase the risk of cancer development.

"Therefore a similar scenario is likely to be occurring in the breast, whereby resident microflora impact on stem cell division and influence cancer risk."

A.K. Marwaha, J.A. Morris, R.J. Rigby. Hypothesis: Bacterial induced inflammation disrupts the orderly progression of the stem cell hierarchy and has a role in the pathogenesis of breast cancer. Medical Hypotheses, 2020; 136: 109530 DOI: 10.1016/j.mehy.2019.109530"

October 7, 2018

Alcohol can increase the risk of breast cancer because it increases estrogen. Soy may also be in that category. Yearly mammograms increase the chance of early detection. Don't miss getting them. Stage 1 is much more treatable than Stage 2 and above and 1/8 of all women get breast cancer.

October 8, 2018

Technically alcohol increases estrogen because the liver is what removes both alcohol and estrogen. The more you drink, the less effective your liver becomes at removing the estrogen from our bodies - which can cause an imbalance in levels, which can increase your risk of breast cancer. It's good to get your hormone levels checked regardless of if you drink or not as there are MANY things that can cause imbalances. Once you get them in check, your risk decreases tremendously (unless you have the BRCA gene). And yes, GET YOUR MAMMOGRAMS. #breastcancersurvivor

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