Antioxidants and Free Radicals
All cells face constant threats from what are known as free radicals. We obtain these potential scoundrels from the metabolism of the food we eat, the air we breathe and from sunlight’s action. Free radicals are in varying chemical states, but their main danger lies in their need for obtaining electrons for stability. In order to do this, they “steal” electrons from nearby substances such as body cells and DNA, causing potential damage and destruction. They may damage the instructions in a DNA strand creating a harmful mutation or create low-density lipoproteins (LDL) that could increase heart disease risk in an artery of the heart, or alter a cell membrane that could affect what enters or leaves a body cell. The body also uses free radicals in a necessary way as part of the immune system to help destroy foreign invaders such as bacteria, viruses, and toxins.
Antioxidants are found naturally in the body such as glutathione, coenzyme Q10, superoxide dismutase among other systems. We obtain many from various foods in the form of vitamins (C, E, beta-carotene and related carotenoids), minerals (selenium, manganese) and various phytonutrients such as flavonoids, phenols, polyphenols, phytoestrogens, and many more found in many plant foods.
Antioxidants probably number in the hundreds or thousands of different substances. Their main function is to act as an electron donor to help squelch the actions of harmful free radicals. Some antioxidants in certain situations can be called prooxidants – electron grabbers. This is likely to be the method found in the defense of the body (e.g. immune system) Nevertheless, they are all considered to be unique with different roles. “So, no single antioxidant can do the work of the whole crowd.” We obviously need a variety of foods to provide as many as we need to get the job done.
Health Benefits of Antioxidants – What’s the Hype?
Antioxidants came into attention when the research suggested that free radical damage may be involved in chronic diseases such as heart disease, cancer, and vision loss. Studies initially indicated that people who ate the most fruits and vegetables had lower risk of these diseases than people who ate lesser amounts. Clinical trials began to test individual nutrients found in fruits and vegetables that were known antioxidants (vitamin C, E, and beta-carotene) to test their efficacy against these diseases. This took the food and supplement industry and media by storm for a long time with proclaiming protection against diseases by consuming large amounts of antioxidants provided by their products.
However, despite these results and disappointments, antioxidant supplements represent a $500 million-dollar industry that continues to grow. Antioxidants continue to be added to cereals, sports and energy bars and drinks, and other processed foods. Lately, however, the hype appears to have abated somewhat due to the reports of no effects of these vitamins and minerals, and phytochemicals (my opinion).
Heart Disease and Antioxidants
In the Women’s Health Study, 39,876 women took 600 IU of natural vitamin E or a placebo every other day for 10 years. The results? At the end, the rates of major cardiovascular events and cancer were no lower among those taking vitamin E than they were among those taking the placebo. One large study (the HOPE Trial) found that those taking Vitamin E versus a placebo showed no benefits vs the placebo and vitamin E and that those in the Vitamin E group actually had higher risks of heart failure and hospitalization for heart failure. Not all trials were negative, however. In a recent trial of vitamin E in Israel, there was a market reduction in coronary heart disease among people with type 2 diabetes.
In the Women’s Antioxidant Cardiovascular Study, vitamin E, vitamin C and/or beta-carotene had much the same effect as a placebo on myocardial infarction, stroke, coronary revascularization, or cardiovascular death, although there was a modest and significant benefit for vitamin E among women with existing cardiovascular disease.
Age-Related Eye Disease and Antioxidants
Some good news for antioxidant supplements was found in a six-year trial, the Age-Related Eye Disease Study (AREDS). The results were that a combination of vitamin C, vitamin E, beta-carotene, and zinc offered some protection against the onset of advanced age-related macular degeneration in people who were high risk for the disease.
Potential Hazards of Antioxidants
Several studies have raised some concerns about supplemental beta-carotene. One study even found that when smokers were fed beta-carotene supplements, the chances of developing lung cancer were increased. Follow-up studies reported the same results. Another possible caution: In the SU.VI.MAX Trial, rates of skin cancer were higher in women assigned to take vitamin C, vitamin E, beta-carotene, selenium, and zinc supplements.
The studies so far have been inconclusive and are far from providing strong evidence that supplementation with antioxidants have much impact on chronic disease prevention. There was some positive benefits of beta-carotene on cognitive function in the Physicians’ Health Study after 18 years of follow-up; however most studies are of shorter duration, so few comparisons can be made.
What to do? There is abundant evidence that the first observations of fruit, vegetable and whole grain consumption were correct since subsequent studies have supported the fact that consumption of antioxidants via eating natural whole foods provides protection against many of our common chronic diseases.
Bottom Line: Get your antioxidants from whole, natural foods, not supplements. Research is still limited and results are not conclusive, but supplement companies still claim benefits even though more evidence of safety and efficacy is sorely needed.