Foodborne Chemicals: Heterocyclic Amines ^20,21and Nitrates

Heterocyclic amines (HCAs) are carcinogenic compounds that form during cooking of all meats, including fish. In general, grilling causes the greatest amount of HCA formation, followed by pan–frying. Chicken products contribute the greatest quantity of HCAs in North American diets, compared with other meats, in part due to the quantity of chicken products consumed. Several cancers are associated with HCAs, including those arising in the colon and rectum, stomach, breast, lung, and prostate. Modification of cooking methods (such as microwaving) and reducing meat consumption are effective preventive steps.

The intake of cruciferous vegetables, such as broccoli and Brussels sprouts, has been found to increase HCA metabolism in humans by induction of hepatic detoxification enzymes.^22–24

Nitrates

Nitrates and nitrites are used as preservatives in hot dogs, pickled meats, some cheeses, and other foods. They are metabolized in the body to form N–nitroso compounds, which are associated with gastric cancer. Nitrates are also a natural component of many vegetables, and produce commonly contains nitrate residues from fertilizers. However, despite the presence of nitrates in and on many fruits and vegetables, protection from gastric cancer is afforded by the consumption of these foods, presumably because of the inhibitory effect of vitamin C on the formation of N–nitroso compounds.

Other foods and nutrients also inhibit N–nitroso compound formation. These include polyphenolic compounds in fruits and vegetables;²⁵ garlic and other allium species²⁶; and vitamin E and selenium.²⁷