Sesame (Sesamum indicum) seeds and sesame oil have been shown to have antioxidant, antihypertensive, cholesterol lowering, and blood sugar lowering properties. Sesame seeds are an abundant source of fiber, copper and iron and also are a source of calcium, campesterol, CoQ10, magnesium, manganese, phosphorus, selenium and zinc.
In addition, sesame seeds incorporate the lignans sesamol, sesamin, sesamolin, and sesaminol, which have been shown to have anti-cancer properties. Sesamol has been shown to inhibit melanin synthesis in mouse melanoma cells, resulting in reduced viability and proliferation of the cells. Sesaminol glucosides have been shown to inhibit carcinogenesis of premalignant lesions of rat colon in the laboratory. One Korean study found that frequent consumption of sesame seed oil was associated with reduced risk of stomach cancer.

Breast cancer-related effects of consuming sesame seeds and sesame oil

While sesame seeds and sesame oil have some chemopreventive properties, on balance their consumption should be limited or avoided for those with breast cancer.

Sesame has some chemopreventive properties

Sesame seed lignans are converted in the human intestine to the estrogen-like compounds enterolactone and enterodiol. The sesame seed lignan sesamin has been found to reduce mammary tumor size in rats with hormone receptor positive (ER+/PR+) tumors. Postmenopausal women with breast cancer and a high intake of the lignan enterolactone have been found to be less likely to die from their breast cancer than those with a low intake. Enterolactone has also been found to increase the sensitivity of breast cancer cells to radiation, thereby potentially enhancing the treatment effects of radiotherapy.
Sesame seeds are a very good source of fiber. High intake of dietary fiber has been reported to be associated with reduced risk of breast cancer. Sesame seeds are also a good source of dietary selenium, which has been linked to reduced risk of breast cancer. One study of Chinese women found a reduction in the risk of breast cancer among women who used sesame oil for cooking compared with those who did not.

Sesame has the potential to promote breast cancer

Cell and animal studies report sesame can promote ER+ disease
There is evidence that sesame seeds and sesame seed oil can promote breast cancer under some circumstances. Several studies have found that sesame seed compounds can stimulate the growth of estrogen-dependent (ER+) breast cancer cells. A 2024 study reported that sesame oil effectively maintained serum estradiol (E2) and aromatase levels in ovariectomized rats.
A study using a mouse model of premenopausal ER+ breast cancer to evaluate the interaction between tamoxifen and dietary sesame seeds reported that the sesame seed diet failed to inhibit breast cancer growth. In fact, the sesame seed diet partially negated the cancer inhibitory effect of tamoxifen by promoting cancer cell proliferation and decreasing apoptosis (programmed cell death).
Sesame seeds are abundant in copper
Sesame seeds contain approximately of 0.4 mg of copper per ounce, which could contribute to angiogenesis (new blood vessel formation) and metastasis of breast cancer, especialy in women with inflammatory breast cancer (IBC) or triple negative (ER-/PR-/HER2-) disease. Although copper is a vital nutrient, women with breast cancer who are not anemic probably should not exceed the RDA (recommended dietary allowance) of approximately 0.9 mg.

Additional comments

Highly refined sesame oil is less desirable than extra-virgin or cold pressed sesame oil since refining greatly reduces the lignin content of the oil. Cold-pressed sesame oil made from raw sesame seeds is close to colorless. Toasted sesame oil is darker since the seeds are roasted before processing.
Sesame seeds are prone to molds which produce aflatoxins, which are mutagenic, carcinogenic and teratogenic and cause immuno-suppression in humans. Aflatoxin B1 has been shown to cause liver cancer, especially in hepatitis B-positive individuals. Sesame paste and sesame seed butter produced in China are subject to less stringent quality and safety standards than U.S. products and even these relatively low standards may not be met. One Chinese study found aflatoxin B1 in 37 of 100 sesame paste samples measured.
There is some evidence that breathing cooking oil fumes can contribute to lung cancer and that sesame oil heated to the smoking point may act as a carcinogen.
Tahini, a paste used in Near and Far East cuisine, is made of ground sesame seed kernels. Halvah is a confection made with tahini.

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 sesame seeds, sesame oil and their components. For a more complete list of studies, please click on sesame.