Radical therapy
It seems blindingly obvious. As our cells metabolise the food we eat, they produce rogue molecules called free radicals that wreak havoc. Over a lifetime, the damage they do slowly builds up and may cause all kinds of degenerative diseases. Luckily, though, many chemicals can act as antioxidants that mop up free radicals. Plus, eating vegetables rich in antioxidants seems to reduce the risk of degenerative diseases. So popping pills packed with antioxidants must surely help stave off these diseases too?
That鈥檚 what some scientists started thinking from the 1970s onwards. Linus Pauling enthusiastically promoted high doses of vitamins without waiting for the evidence, the public lapped it up and a whole new industry sprang up to meet demand.
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Then, in the 1990s, the results of rigorous trials of some of the most popular supplements, including beta carotene, vitamin E and vitamin C, started to come in. Study after study has found that while these substances do work as antioxidants in the test tube, popping the pills does not provide any benefit.
On the contrary, some studies suggest that they are harmful. A 2007 review of nearly 70 trials involving 230,000 people concluded that not only do antioxidant supplements not increase lifespan, but that supplements of beta carotene and vitamins A and E actually seem to increase mortality ().
Why? Perhaps because high levels of free radicals tell cells to ramp up their own built-in antioxidant defences, says Barry Halliwell, a biochemist at the National University of Singapore. He thinks these internal defences are far more effective than the antioxidants we get from food. So by taking supplements we may be deactivating a first-rate defence mechanism and replacing it with a poorer one (). 鈥淔ree radicals in low amounts also play useful roles,鈥� Halliwell says.
If this is right, the benefits of vegetables may have nothing to do with antioxidants. One suggestion is that vegetables are beneficial because they are mildly poisonous 鈥� a little poison may activate protective mechanisms that ward off disease.
In the meantime, the antioxidant juggernaut rolls on. No one seems keen to abandon the idea that antioxidant supplements are good for you.
Read more: 鈥�Don鈥檛 swallow it: Six health myths you should ignore鈥�
This article appeared in print under the headline 鈥�4 Antioxidant pills help you live longer鈥�
