Selenium is a trace element obtained from our diets that is necessary for different cellular functions. Selenium has been noted to have antioxidant activity.

Certain strains of laboratory rats are prone to developing breast tumors when exposed to particular chemicals. This makes them good research subjects for studies looking at the origin of breast cancer and its possible treatments. In one experiment, a group of these rats was exposed to the tumor-inducing chemical and then fed selenium and/or retinyl acetate. Although selenium alone had no effect on the rate of development of breast tumors, the combination of selenium and retinyl acetate produced a significant reduction in the breast cancer rate.³⁶

In Japan, where seaweed is a popular part of the diet, the incidence of breast cancer is lower than in the US. Seaweed contains both iodine and selenium. Although iodine has known benefits in reducing thyroid goiter and benign breast disease, iodine plus selenium works even better.³⁷ More work is ongoing to determine if these two elements together are indeed a potent anti-cancer antioxidant combination.

Older people whose diets are deficient in such substances as zinc, vitamin B6 and selenium have been observed to have weakened immune systems.³⁸

Many people with cancer are treated with radiation therapy, but radiation can damage the healthy tissue that surrounds the cancerous cells. This radiation damage is due to oxidative processes. In a study of rats that were given abdominal radiation, selenium and/or vitamin E reduced the oxidative damage to the cells of the intestine and thus reduced the amount of radiation injury the rats sustained.³⁹ Whether selenium can reduce radiation injury in human cancer patients is not yet known.

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Coenzyme Q10 is an antioxidant thought to have benefits in heart disease.

Pigs have hearts quite similar to humans, and many heart treatments are studied in pigs before they are tried in people. A herd of laboratory pigs was divided into two groups. Half were given diets high in coenzyme Q10, and half received no supplementation. Both groups were then subjected to deliberate heart attacks, by tying off one of their coronary arteries. The coenzyme Q10 group of pigs had smaller heart attacks and less heart failure than the second group.⁴⁰

The promising pig results prompted studies of coenzyme Q10 in humans with heart failure. Patients with heart failure were given supplements of coenzyme Q10 or placebo. Disappointingly, at the end of the study, there was no difference between the two groups in either heart pumping strength or exercise tolerance.⁴¹ Other studies of coenzyme Q10 and heart disease are ongoing.

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BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene) are synthetic antioxidants used as preservatives in many packaged foods. Studies are underway to determine whether these added antioxidants might have any health benefits.

Laboratory rats given supplements of BHA and BHT that are then exposed to cancer-causing chemicals developed far fewer precancerous changes in their DNA than rats that had not received the supplements.⁴² This was the first study to show any anti-cancer benefit in these synthetic antioxidants.

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Melatonin is a substance secreted by the pineal glands in our brains. Because melatonin is known to have antioxidant properties, studies have begun to see if melatonin supplements can reduce the risk of certain diseases.

Chromium compounds are known to cause cancers in humans through oxidative damage to DNA. In cell cultures, calf tissue was exposed to chromium and then treated with vitamin C, Vitamin E or melatonin. Melatonin was 60 times more likely to prevent oxidative damage to the calf cell DNA than either vitamin.⁴³

Melatonin combined with retinyl acetate dramatically reduced the risk of breast cancer in laboratory rats, although melatonin alone had little effect.⁴⁴ Whether melatonin has any effect in cancer prevention in humans remains to be seen.

In a study of laboratory rats given deliberate heart attacks, those rats pre-treated with melatonin had smaller heart attacks (with less heart muscle damage) than those who had no treatment.⁴⁵

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The flavonoids found in green tea (and also in black tea) have been observed to have antioxidant effects in laboratory studies. Mice fed diets high in the flavonoids of green tea develop fewer skin tumors after ultraviolet radiation than mice who had received no flavonoids.⁴⁶

Flavonoids have been observed to improve diabetic control, apparently by promoting the action of the antioxidant glutathione and preventing vitamins C and E from being consumed in oxidative processes.⁴⁷

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A few studies have suggested that natural honey has antioxidant properties.

Laboratory rats deliberately given stomach ulcers were then treated with either natural honey or nothing. The honey-treated rats had far less ulcer damage.⁴⁸

Natural honey has been observed to promote wound healing. In cell culture, honey inhibits the growth of both bacteria and fungi. The antimicrobial effect of honey is likely due to the presence of antioxidant flavonoids.⁴⁹

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