Scientists bust the antioxidant mythComment on this story
London - We all want to stay as healthy and young-looking as possible, which is why millions of us dutifully take antioxidant supplements such as vitamins C, E and beta-carotene, as well as splashing out on costly antioxidant “superfoods” such as blueberries.
For years we’ve swallowed the line from scientists that antioxidants could slow the rate at which our cells - and therefore our bodies - age. The theory is that antioxidants reduce the ‘oxidising’ damage caused by free radicals - corrosive molecules produced by our bodies as we process oxygen, and which we also breathe in from polluted air and smoking.
It is thought that when these free radicals attack proteins and lipids (fats in the cells), it breaks down the cell membrane and damages the DNA inside. This in turn may cause cancerous mutations, as well as making the cells age more rapidly. Free-radical damage to brain cells is also believed to cause the sort of drops in cognitive functioning associated with ageing.
In Britain, we spend £175-million a year on antioxidant supplements - but a new study suggests we might be wasting our money. Not only do free radicals not cause ageing, say researchers at McGill University in Canada, but taking antioxidant pills may actually make our bodies age faster- making them a short cut to an early grave. So what is going on?
When free radicals interact with the cells, proteins and DNA in the body, they can cause damage by interfering with their chemical structure. Until now, it has been believed that, as a result, we inevitably suffer the ravages of ageing, from normal physical ageing to diseases such as cancer.
But the Canadian study, published in the respected journal Cell, says the opposite. Researchers found that free radicals can make our cells live longer.
This happens by altering a mechanism called apoptosis. This is a process by which damaged cells are instructed to commit suicide in a variety of situations, such as to avoid becoming cancerous when their DNA has mutated dangerously, or to kill off viruses that have invaded the cell.
The scientists have found that free radicals can stimulate this “suicide mechanism” to do something completely different in healthy cells - bolstering their defences and increasing their lifespan.
Siegfried Hekimi, professor of biology at McGill University, who led the study, says: “The so-called free-radical theory of ageing is incorrect. We have turned this theory on its head.”
Professor Hekimi says that when he raised levels of free radicals in nematode worms (these simple roundworms are used because their nervous system performs many of the same functions as higher organisms), he got the creatures to live “a substantially longer life”.
His study reinforces suspicions raised by other scientists. Last year, for example, researchers at the Multimedica Cardiovascular Research Institute in Italy warned that our bodies need the stress caused by free radicals to stimulate them to fight infectious disease and to properly regulate vital bodily functions such as our cardiovascular system.
The Milan-based researchers had surveyed all previous research evidence and concluded in The International Journal of Biochemistry and Cell Biology: “Increasing the levels of antioxidants in our bodies may harm our health. Balanced levels of antioxidants are important for our cardiovascular system and for healthy ageing.”
The theory behind this idea is called hormesis - which may be more described as “what doesn’t kill you, makes you stronger”.
Scientists believe our bodies have evolved an array of defence mechanisms for surviving tough environments, but that these systems are not switched on unless we are challenged. And that is where free radicals come in.
The problem with antioxidants is that they may neutralise this “protective” effect. It may also help explain why antioxidant pills have been found to produce some unexpectedly harmful results.
For instance, laboratory studies have shown how high doses of antioxidants such as N-acetyl cysteine - a popular antioxidant supplement - may promote the spread of breast cancer cells.
Meanwhile, the antioxidants beta carotene and vitamin A have been linked to an increased risk of death from lung cancer and lung disease.
The precise reasons for this remain uncertain. However, some studies, such as one performed in 2009 by Harvard Medical School and published in the prestigious science journal, Nature, have indicated that the high-dose supplements may, ironically, help rogue cancer cells survive and multiply - by shutting down the free radicals and their stimulation of the body’s self-repair mechanisms.
Here, it is important to point out the antioxidants derived from the food we eat are important. The amount we consume in this way is much lower than the quantities found in supplements. At these lower levels they are thought to provide a protective effect.
But recent research findings about free radicals may be a disappointment to the legions of us who take antioxidants in the hope they will extend our lifespans and keep us looking youthful.
However, according to Helen Bond, of the British Dietetic Association, the answer was never to be found in a bottle.
“Whether or not there are benefits from antioxidant vitamins, the best way to get them is from a diet that is rich in fruits and vegetables,” she says. “You get important vitamins, many of which have antioxidant properties, but you also get all the other benefits that come from eating whole foods.
“Vitamin supplements may be of use to young children, elderly people and pregnant women, but for the rest of the population it is far better to focus on diet, and spend money on fresh, wholesome food instead.” - Daily Mail