Week 21 – The antioxidant myth

A recent article in New Scientist throws significant doubt on the value of consuming antioxidants for various health reasons. (New Scientist, 5 August 2006).

We have all heard of antioxidants. A search on Google brings up over 10 million hits for the term. According to some estimates around half the adults in the US take antioxidant pills daily in the belief they promote good health and stave off disease.

“Our cells produce thousands of free radicals every day. Free radicals from the environment occur as an effect of stress, pollution and unhealthy eating habits. … Fortunately, we can protect our bodies with the super power of antioxidants.”

“Recent tests have shown that … is the most powerful antioxidant in the world, in fact, it is 902 times more powerful than vitamin E and 216 times more powerful than vitamin C.”

“… is ten times stronger than beta carotene and up to 500 times stronger than vitamin E as an antioxidant. Other unique aspects of its structure allow it to pass the "blood brain barrier", meaning it can deliver antioxidant benefits directly to the brain and central nervous system.”

However, evidence gathered over the past few years shows that at best, antioxidant supplements do little or nothing to benefit our health. At worst, they may even have the opposite effect, promoting the very problems they are supposed to stamp out.

Stephen Barrett has written (http://www.quackwatch.org/) “It is known that people who eat adequate amounts of fruits and vegetables high in antioxidants have a lower incidence of cardiovascular disease, certain cancers, and cataracts. Fruits and vegetables are rich in antioxidants, but it is not known which dietary factors are responsible for the beneficial effects. … Only well-designed long-term research can determine whether any of these chemicals, taken in a pill, would be useful for preventing any disease.”

An article on Wikipedia (http://en.wikipedia.org/wiki/Antioxidant) describes the field in some detail. What comes across is that this is an extremely complex area. The concept of oxidation is intimately tied to life as we know it. As New Scientist says, “Free radicals are an unavoidable hazard of being alive. We live in an oxygen-rich atmosphere, and radicals… are natural by-products of respiration.”

The myth dates back to the 1980s. Scientists had known for a long time that people whose diets are rich in fruits and vegetables have a lower incidence of heart disease, diabetes, dementia, stroke and certain types of cancer. The hypothesis developed that antioxidants are free-radical sponges which can stave off the diseases of old age. An additional leap was then made, that taking them as supplements or in fortified foods would decrease oxidative damage and diminish disease. It seemed an obvious conclusion...

However, over the last 20 years scientists have been putting these compounds through their paces. True, antioxidants knock the wind out of free radicals in a test tube. But once inside the human body, they appear to be bad at preventing oxidative damage, and they can even make things worse. There are some serious horror stories surrounding beta carotene supplements: In May 2006 an expert panel convened by the NIH concluded that there was no evidence to recommend beta carotene supplements for the general population, and strong evidence to recommend that smokers avoid it. Similar results exist for vitamin E, the world’s most popular antioxidant, as well as vitamin C.

Now, no-one is saying that there are not advantages to following a healthy diet. If you improve your diet, and eat many fruits and vegetables, you are bound to benefit. But it is wishful thinking if you think you can simply pop a few pill supplements each day to avoid the consequences of eating badly. And, as with iron supplements, there is the serious possibility that you can damage your health by excessive pill popping. Which brings me to an important point made, again, I think, by Stephen Barrett: For most of us, you can obtain much more significant health benefits simply by improving your diet and lifestyle: Exercise more, smoke less, eat more fruits, nuts and vegetables, and keep your weight under control.

To which I would add: Drive carefully, and don’t go out into the sun without a hat and your sunscreen!