Mustard is recommended for breast cancer in moderation

Like horseradish sauce, mustard is made from a brassica vegetable. The yellow mustard commonly used in the U.S. is made from the ground seeds of the white or yellow mustard plant (Sinapis alba Linn., otherwise known as Sinapis hirta), which are mixed into a paste with water, vinegar, curcumin and other spices or flavorings. Mustard is also made from brown or Indian mustard (Brassica juncea) seeds or black mustard (Brassica nigra) seeds. Brown and French-style mustards typically are made with Indian mustard seeds. Mustard greens, which are the leaves of Indian mustard, are covered in a separate web page. Biologically active compounds in various mustards include sulforaphane, allyl isothiocyanate, alpha-linolenic acid, sinalbin, sinigrin, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid. Components of mustard have been shown to have antimutagenic, antidiabetic, antifungal, antimicrobial and antioxidant effects. White mustard seed has been shown to inhibit colon cancer formation when added to the diets of both normal and obese rats. Brassica compestris, another mustard grown in India, has been shown to inhibit the formation of carcinogen-induced stomach and uterine cancer in mice. Cruciferous vegetables have also been shown to reduce the risk of gallbladder and urinary bladder cancer and to inhibit the proliferation of lung, pancreatic, and prostate cancer cells.

Breast cancer-related effects of eating mustard

Sulforaphane, a component of mustard, has been found to inhibit the proliferation of human breast cancer cells. Oral administration of either sulforaphane, or its glucosinolate precursor, glucoraphanin, has been shown to inhibit carcinogen-induced mammary carcinogenesis in rats. A small study of healthy women undergoing breast reduction found that sulforaphane metabolites were readily measurable in the breast tissue removed during surgery after ingesting a single dose of a brassica vegetable preparation containing 200 µmol of sulforaphane, indicating that the substance is bioavailable after consumption. Sulforaphane has been shown to arrest proliferation and mitosis of breast cancer cells in a manner weaker than, but similar to, antimitotic chemotherapy drugs such as the taxanes paclitaxel and docetaxel. While one carefully designed study of Chinese women found that brassica vegetable consumption was associated with significantly reduced breast cancer risk, population studies specifically evaluating the impact of consuming mustard seed are not available.

Additional comments

Indian mustard is known for its tendency to incorporate heavy metals and other minerals (e.g., cadmium, arsenic and lead) from its soil. This property has been used to develop a high-selenium mustard (i.e., Brassica juncea that has been grown in soil with high levels of selenium) for use in combating prostate and other cancers (see the discussion regarding selenium and breast cancer in our brazil nuts web page). However, it also means that pollution resulting in heavy metal contamination of soil will result in the accumulation of high concentrations of such substances in locally grown mustard, with potentially harmful health effects. Heavy metal contamination of agricultural soils and stream sediments have been reported in many countries, including China near coal and copper mines, in India near tanneries, and in Russia near uranium plants and heavy metal smelting complexes. Much of the foreign Indian mustard consumed in the U.S. is imported from Canada, but it is also imported from parts of the old Soviet Union, India and China. Buyers of Indian or black mustard from specialty markets should be aware of its source and assure themselves of its safety and quality.

Although it is used widely in Indian cooking, depending on the mustard seed from which it is prepared, mustard oil (mustard seed oil) can be hazardous to health because of its high content of erucic acid and/or allyl isothiocyanate. In addition, mustard oil adulteration (e.g., the addition of argemone oil, a poison) has occasionally been reported in India. Mustard oil has been shown to cause early carcinogenic changes in rat livers, especially when consumed after the oil has been heated to the boiling point. The FDA has not approved mustard oil for human consumption. We do not recommend using it.

Mustard oil should not be confused with mustard essential oil (also known as volatile oil of mustard) which is produced by grinding the seeds, adding water, and extracting the resulting volatile oil by distillation. The high allyl isothiocyanate content of mustard essential oil makes it frankly toxic when used undiluted.

Tags: Chinese, EasternEurope, Indian, Taxol, Taxotere, antifungal, cadmium, chemotherapy, curcumin, docetaxel, greens, mustard, paclitaxel, selenium, sulforaphane, taxanes

Selected studies

Regulation of estrogen receptor α expression in human breast cancer cells by sulforaphane Journal of Nutritional Biochemistry, March 2009

Sulforaphane [1-isothiocyanato-4-(methylsulfinyl)butane] is an isothiocyanate in cruciferous vegetables with a number of potential chemopreventive actions. The current study examined the effects of sulforaphane on the proliferation of human MCF-7 breast cancer cells and on the expression of estrogen receptor α (ERα) protein and mRNA in the cells. Sulforaphane was found to inhibit cell proliferation and ERα protein expression. Lowered ERα expression was also found to be accompanied by decreased progesterone receptor expression. MCF-7 cell mRNA expression was inhibited by sulforaphane at relatively high doses, but not at low sulforaphane concentrations. The authors conclude that sulforaphane can inhibit proliferation of MCF-7 breast cancer cells and down-regulation of hormone receptor expression.

Effect of dietary allyl isothiocyanate from Brassica vegetables on serum glutathione S-transferase-α concentration The FASEB Journal, 2008 22:887.11

In the current crossover study, the anticancer activity of allyl isothiocyanate, a compound derived from foods including brown mustard and green cabbage, was evaluated. Twelve men and 34 women were selected in part by genotype for DNA repair enzyme gene XPD and glutathione S-transferase (GST) M1. Subjects participated in three treatment phases with an 11-day basal diet supplemented as follows: (1) 11.4 mg allyl isothiocyanate; (2) 100 g pureed cabbage plus 30 g brown mustard; and (3) unsupplemented control. Baseline blood samples were collected on day one and blood collection was repeated on day 11. Outcome measures included COMET, 8-oxo-dG, F2-isoprostanes, IL6, VEGF, GST activity, and GST-α concentration. Unexpectedly, the mustard allyl isothiocyanate content was found to decrease over time. The response of GST-α concentration to treatment was proportional to baseline values, but the degree of response was higher for participants on the allyl isothiocyanate treatment. Consumption of the pureed cabbage plus brown mustard treatment resulted in increased log GST-α concentration independent of baseline value. The authors indicate that evaluation of other outcome measures and the effect of genotype on treatment response is underway.

Novel mucilage fraction of Sinapis alba L. (mustard) reduces azoxymethane-induced colonic aberrant crypt foci formation in F344 and Zucker obese rats Phytomedicine, August 2007

In the current study, the efficacy of a novel mucilaginous fraction of mustard seeds in inhibiting precancerous colon changes associated with sporadic and obesity-related colon cancer was assessed. Seeds of Sinapis alba Linn. (yellow or white mustard) and their constituents have been reported to possess anticancer activities. In two separate studies, male Sprague-Dawley and female Zucker obese rats were injected with the carcinogen azoxymethane once per week for two weeks. The rats were fed purified AIN-93G rodent diets with or without 5% mustard mucilage for eight weeks. The main study aim was to measure the ability of the mustard mixture to modulate the number of aberrant crypt foci, i.e., presumed preneoplastic lesions of the colon. The data were classified into total numbers of aberrant crypt foci and large aberrant crypt foci (with crypt multiplicity of four or more). The 5% mustard mucilage treatment was found to significantly (p<0.05) lower the overall total (~21% inhibition) and large (~50% inhibition) numbers of aberrant crypt foci in the colons of the male Sprague-Dawley rats compared to the untreated controls. The mustard mucilage supplemented diet was also found to significantly decrease (p<0.05) the total (~63% inhibition) and large (~60% inhibition) colonic aberrant crypt foci in the female Zucker obese rats compared to the untreated obese controls. This diet was also found to have no effect on fasting plasma cholesterol or triglyceride levels in the obese rats. The authors conclude that mustard mucilage has a possible role as a functional food against sporadic and obesity-associated colon cancer.

Preclinical and clinical evaluation of sulforaphane for chemoprevention in the breast Carcinogenesis, July 2007

Oral administration of either the isothiocyanate, sulforaphane, or its glucosinolate precursor, glucoraphanin, has been found to inhibit mammary carcinogenesis in rats treated with 7,12-dimethylbenz[a]anthracene. The present study was designed to determine whether sulforaphane exerts a direct chemopreventive action on animal and human breast tissue. The pharmacokinetics and pharmacodynamics of a single oral dose of sulforaphane were studied in the rat mammary gland. Sulforaphane metabolites were detected at concentrations sufficient to alter gene expression in cell culture. In a small pilot study, eight healthy women undergoing breast reduction were given a single oral dose of a broccoli sprout preparation containing 200 µmol of sulforaphane. Following the dosing, sulforaphane metabolites were readily measurable in human breast tissue.

Cisplatin combination with allyl isothiocyanate, a constituent of cruciferous vegetables, synergistically increases cancer cell death through activation of caspase 3 and downregulation of the antiapoptotic protein Bcl-2 and survivin American Association for Cancer Research (AACR) Meeting, April 2007

Cisplatin is one of the first-line chemotherapy drugs in the treatment of many human cancers. Allyl isothiocyanate occurs abundantly in many cruciferous vegetables such as mustard and horseradish and inhibits cancer cell proliferation through inducing G2/M arrest and apoptosis. The present study was designed to determine the combined effects of cisplatin and allyl isothiocyanate cancer cell growth and death. Three cancer cell lines were studied, including a highly invasive human ovarian cancer cell line, the HCT116 colon cancer cell line and the MCF-7 breast cancer cell line. It was found that combining allyl isothiocyanate with cisplatin significantly increased cancer cell death and decreased cell viability in all three human cancer cell lines compared with each substance used alone. The combination significantly increased caspase-3 activation and reduced the expression of antiapoptotic protein Bcl-2. More interestingly, the combination appeared to neutralize the increase in the antiapoptotic protein survivin expression resulting from treatment with either substance alone. Note that both Bcl-2 and survivin are involved in cancer cell survival and chemotherapy drug resistance. In addition, the combination of allyl isothiocyanate and cisplatin was found to alter cell cycle distribution. The authors conclude that combining allyl isothiocyanate and cisplatin significantly increases cancer cell death as compared with using each compound alone, thus potentially providing a new strategy for cancer treatment.

Enhancing effects of mustard oil on preneoplastic hepatic foci development in Wistar rats Human & Experimental Toxicology, February 2003

The present student was designed to determine the effect of mustard oil on the livers of laboratory labs. Mustard oil, used extensively in India and elsewhere as a frying and cooking medium, has been reported to induce an inflammatory response. When rat liver cancer is induced by the carcinogen diethylnitrosamine, an early carcinogenic change is the development of altered hepatic foci. In the current study, the development of preneoplastic lesions was found to occur following administration of mustard oil (0.5 mL/day for eight weeks) in diethylnitrosamine-initiated and partially hepatomized Wistar rats. The relative and absolute liver weights of the mustard oil-exposed rats also was found to decrease significantly. This was associated with a significant increase in the number and area of placental glutathione S-transferase-positive and g-glutamyl transpeptidase-positive foci. In addition, the glutathione S-transferase and g-glutamyl transpeptidase-positive foci were found to be more prominent in the animals given boiled mustard oil compared to the animals given fresh mustard oil. The authors conclude that these results indicate a possible tumorigenic risk associated with mustard oil consumption.