If, 15 years ago, you were au fait with the word antioxidant, then you probably had a chemistry degree. These days, you’re almost certainly an expert on the subject yourself. Every time we read a magazine, turn on the TV or pop to the supermarket, we’re bombarded by claims about the ability of these apparently miraculous chemicals to ward off serious illness and help us live longer. As a result, swathes of the public, in particular the “worried well”, now expound knowledgeably about the “antioxidant power” of their purchases from the fruit and veg counter at Waitrose to neutralise the dangerous ”free radicals” in our bodies.
But although “antioxidant good, free radical bad” has become the nutritional rallying cry of a generation, scientists say that worrying questions remain about the complex role the two interlinked chemicals play in our lives. This has been underlined by new research suggesting that, far from protecting us from harm, high doses of antioxidants can do significant damage to our bodies.
Scientists at the Cedars-Sinai Heart Institute in Los Angeles reported in the journal Stem Cells that high doses of antioxidant supplements, such as vitamins C and E, raised the risk of dangerous changes in human cells.
“In simple terms, by taking high amounts of antioxidant supplements, you may be increasing your chances of cancer,” explained the team leader, Dr Eduardo Marbán.
Confused? Before we turn to Dr Marbán’s explanation, it’s worth recapping what we do – and don’t – know about free radicals and antioxidants. The starting point is that our bodies generate a class of molecules called free radicals, both as a by-product of our normal metabolic processes and as a result of contact with pollutants. These reactive molecules contain oxygen atoms with unpaired electrons. Since electrons have a very strong tendency to exist in a paired rather than an unpaired state, the free radicals indiscriminately “seek” to grab electrons from nearby molecules. These are then converted into secondary free radicals, setting up a chain reaction that damages our tissue.