In recent decades, scientists have begun to recognize the profound impact that vitamins, minerals, and other nutrients have on our health. Because antioxidant vitamins are usually the focus of scientific scrutiny, the value of minerals as part of an anticancer diet is frequently overlooked. However, minerals can play a vital role in fighting cancer.
A prime example is the mineral selenium, which has powerful antioxidant properties. Like vitamins C, E, and beta-carotene, it counteracts the harmful effects of free radicals—stray, highly-reactive forms of oxygen and nitrogen that accumulate in the body as byproducts of normal metabolism. Free radicals ricochet wildly, injuring surrounding cells in a process called oxidation. Left unchecked, free radicals can damage DNA, potentially causing cancer. Free radicals are linked not only to cancer but to many other diseases as well as the aging process.
Studies supporting a connection between selenium intake and cancer risk have not always produced consistent results, but data do suggest that a diet rich in selenium protects against cancers of the stomach, esophagus, lung, prostate, colon, and rectum.
In addition to neutralizing free radicals, selenium appears to help fight cancer by enhancing vitamin E’s antioxidant activities. Selenium also appears to increase the body’s immune response, produce antioxidant enzymes, suppress cell proliferation (a cancer precursor), and perhaps alter the metabolism of carcinogens (cancer-causing substances) so that the body produces fewer toxic substances.
Supplements of selenium are not recommended, since selenium is a trace mineral, which means it is needed only in tiny amounts. Consuming excess levels of a trace mineral in the form of supplement pills can throw the body off balance, interfering with the metabolism and absorption of other nutrients.When large amounts of trace minerals are consumed in food, however, the body maintains its ability to balance its needs, storing the required amounts and excreting the excess. Thus consuming selenium in foods, not pills, is the safest strategy. Fish, grains, and meat are the best dietary sources of selenium.
Calcium is also a mineral with cancer-fighting properties. In sharp contrast to trace minerals, calcium is the most abundant mineral in the body. It is best known for building strong bones and reducing the risk of osteoporosis. But calcium has many other functions, playing a role in transmission of nerve impulses and regulation of muscle contraction, blood pressure, and immune defenses. Most relevant, the latest research suggests that a calcium-rich diet may protect against colon cancer by limiting potentially dangerous cell growths. Calcium also appears to bind potential carcinogens to bile and fatty acids that are excreted, thereby decreasing exposure of the colon to cancer-causing substances.
Good dietary sources of calcium include low-fat dairy products, dark green leafy vegetables, almonds and hazelnuts, and salmon and sardines (both canned with bones). Because the body needs large amounts of this mineral, calcium supplements are often advisable. Discuss supplementation with your physician.
Besides selenium and calcium, the anticancer properties of many other minerals are under investigation. Preliminary data suggest a relationship between low intake of magnesium and kidney cancer, for example. Undoubtedly, research will continue to reveal the power of many nutrients in battling cancer. Until we know more, the take-home message is to eat a wide variety of foods in your diet with a heavy focus on fruits, vegetables, and grains to make sure you’re getting at least a little bit of every nutrient.