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, turmeric 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 allyl isothiocyanate (AITC), phenethyl isothiocyanate (PEITC), melatonin, and ferulic acid, as well as sinalbin, sinigrin, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, p-coumaric 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
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.
Both white and black mustard seeds are an excellent source of melatonin. Melatonin protects against breast cancer in several ways, including by reducing aromatase activity within the breast, thereby reducing estrogen production.
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 relatively high content of erucic acid and 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.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on mustard.