Turmeric is a bright yellow spice used extensively in Indian cooking. It made from the dried rhizome (underground stem) of the plant Curcuma longa. Biologically active components of turmeric include several curcuminoids (including curcumin) and other diarylheptanoids, as well as various turmerones and sesquiterpenoids.
Turmeric and its components have been shown to have antioxidant, anti-inflammatory, antibacterial, antifungal, antiparasitic, anti-thrombotic, antiproliferative, anti-angiogenic, radioprotective, neuroprotective and cardioprotective effects.
Curcumin has been shown to inhibit proliferation and induce apoptosis of chronic and acute myeloid leukemia, Burkitt’s lymphoma, melanoma, osteosarcoma, head and neck squamous cell, esophageal, brain, thyroid, lung, synovial, pancreatic, liver, intestinal, colorectal, endometrial, cervical, bladder, ovarian, and prostate cancer cells.

Breast cancer-related effects of consuming turmeric

Curcumin has been shown in the laboratory to have profound and diverse effects on breast cancer development, proliferation and metastasis. Furthermore, these anticancer actions have been observed against several types of breast cancer, including hormone receptor positive (ER+/PR+), triple negative (ER-/PR-/HER2-), and HER2 overexpressing (HER2+) cell lines. Some degree of selectivity for cancer cells (rather than normal breast cells) also has been observed.
While cell and animal study evidence of curcumin's anti-cancer activities is remarkable, there have been no population studies that specifically address the association between turmeric consumption and the risk of breast cancer. India, where turmeric is a dietary staple, has lower overall cancer rates and breast cancer rates than countries in the West (although the rates are rising, particularly in urban areas). One 2005 study found that south Asian women (having origins mainly in India, Pakistan, Bangladesh and Sri Lanka) living in California were 3.5 times more likely to develop breast cancer than native Asian Indian females. However, these results likely are the result of a variety of non-dietary as well as various dietary factors.

Curcumin increases the effectiveness of various chemotherapy drugs

Adding curcumin to chemotherapy regimes that include Taxol (paclitaxel), Adriamycin (doxorubicin), cisplatin, or 5-Fluorouracil (5-FU) has been shown to enhance their cytotoxicity. Curcumin has also been shown to reduce cardiomyopathy in a mouse model of Adriamycin treatment. Curcumin might also protect the brain from chemotherapy, thereby reducing chemo brain. On the other hand, supplementation with curcumin has been shown to interfere with the effectiveness of tamoxifen treatment.

Curcumin is a heavy metal chelator

Curcumin has been shown to be an iron and copper chelator, which may be helpful for some women (since high stores of copper or iron can contribute to breast cancer risk), but could increase risk of anemia in women with marginal levels, especially those undergoing chemotherapy.

Curcumin is radioprotective while increasing radiotherapy effectiveness

Curcumin has been found in mouse models to effectively protect skin from radiation damage, while at the same time sensitizing breast cancer cells to radiation and making them more susceptible to its effects. Therefore, it appears that adding turmeric to the diet during radiation treatment does not lessen the radiation's effectiveness and could be beneficial. Also, there is some evidence that turmeric could help protect normal breast cells from radiation-induced cancer (e.g., when radiation is used to treat other cancers).

Curcumin may help protect against the harmful effects of HRT

Curcumin has been shown to inhibit progestin-accelerated mammary tumors in rats. Combined hormone therapy containing both estrogen and progestin has been found to result in increased risk of breast cancer in postmenopausal women. Treatment with curcumin was found to postpone the first appearance of progestin-accelerated tumors, decrease overall tumor incidence, and reduce proliferation. These results suggest that curcumin might be an effective a dietary chemopreventive agent in women already exposed to combined hormone therapy.

Curcumin may reduce harmful BRCA1 effects

Curcumin can restore BRCA1 expression in triple negative (ER-/PR-/HER2-) breast cancer cells, thereby potentially reducing the effects of harmful BRCA1 mutations in carriers.

Turmeric and curcumin supplements are not recommended

Although turmeric contains 4% to 6% curcumin and related compounds, their bioavailability is limited because of poor absorption and rapid elimination from the body. The levels of curcumin used in laboratory experiments to assess its chemoprotective effects typically are many times higher than that which would result from consuming dietary turmeric.
This has made turmeric and curcumin supplements popular. However, we recommend consuming turmeric as food rather than taking such supplements, whose safety and effective dosages for breast cancer patients and survivors have not been established.

Turmeric and curcumin supplements are high in phytoestrogens

Turmeric contains a number of diarylheptanoids, including curcumin, bismethoxycurcumin, demethoxycurcumin, and other compounds structurally related to them. Depending on their chemical structure, some of the more than 400 diarylheptanoids that have been identified in a variety of plants act as phytoestrogens, i.e., structurally and functionally similar to mammalian estrogens and able to bind to estrogen receptors. However, curcumin and other turmeric diarylheptanoids are only weakly estrogenic and do not produce significant effects when turmeric is consumed in food.
When phytoestrogens bind to cell receptors, they can have either anti-estrogenic activity (which reduces ER+ cell proliferation and growth), or estrogenic activity (promoting ER+ cell proliferation and growth), or both (depending primarily on dosage). Based on available evidence, the phytoestrogens in turmeric are associated with reduced ER+ breast cancer risk.
On the other hand, turmeric and curcumin supplements, which concentrate the phytoestrogens in turmeric, have the potential for adverse effects, depending on the formulation. In any case, they should not be taken during tamoxifen treatment since curcumin has been shown to interfere with the metabolism of tamoxifen and reduce it's treatment efficacy (see our article on tamoxifen and turmeric or curcumin supplements).

Additional comments

Turmeric should be purchased organic. Imported turmeric can sometimes incorporate relatively high levels of lead, in some cases because of the addition of lead chromate (a yellow pigment) to improve its color.
Curcumin has been shown to have a cytotoxic impact on microbes such as the malaria parasite Plasmodium falciparum. One study also showed that long-term use of low-dose curcumin supplementation suppressed immunity against some other microbes (i.e., pathogens whose elimination primarily involves reactive radicals generated from inflammation).
Consuming black pepper along with turmeric may increase the spice's anti-breast cancer action by enhancing breast cancer cell (including breast cancer stem cell) sensitivity to curcumin.

Sources of information provided in this webpage

The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.
Below are links to 20 recent studies concerning this food and its components. For a more complete list, including less recent studies, please click on turmeric.