Vitamin Information Center

The notion that antioxidant supplements such as vitamins C and E could slow ageing has been dealt a blow by a scientific study showing that the theory behind the advice is wrong.

Beloved of health food shops and glossy magazines alike, antioxidants have long been peddled as preventative pills that have the ability to slow ageing and protect against diseases such as cancer. But the research has shown that the molecular mechanism proposed to explain how they work is mistaken.

David Gems, at University College London, who led the study, said: “It really demonstrates finally that trying to boost your antioxidant levels is very unlikely to have any effect on ageing.”

The dominant theory for ageing has been around since the 1950s; it blames glitches in cells caused by the damaging byproducts of our metabolism. As cells break down sugars to release energy, they also unleash reactive forms of oxygen such as superoxide. These supposedly cause the damage which is the hallmark of ageing.

Gems’ team set about testing the theory that raising or lowering the body’s natural defences against superoxide could affect an individual’s lifespan: make the defences stronger, and lifespan should increase; make them weaker, and it should decrease.

As it would be unethical to experiment on humans, his team used the nematode worm, Caenorhabditis elegans. By tweaking its genes, the scientists were able to “tune” the worms’ natural defences - enzymes it produces to tackle superoxide. However, this made no difference to the worms’ lifespan.

“You can drastically change the natural defence levels and there’s just no effect on ageing,” said Gems, who published his results yesterday in the journal Genes and Development. He added that molecular damage was probably caused by numerous different chemicals within the cell.”With increasing lifespan comes greater exposure and vulnerability to the ageing process,” said Alan Schafer, head of molecular and physiological sciences at the Wellcome Trust. “Research such as this points to how much we have to learn about ageing, and the importance of understanding the mechanisms behind this process. This new study will encourage researchers to explore new avenues in ageing research.”

Gems’s findings coincide with a recent US study on the effectiveness of antioxidants against cancer. The clinical trial on nearly 15,000 men tested whether vitamin C and E supplements were effective against the disease. After following the subjects for several years, researchers found no statistical difference in the number of cancers between the groups taking the vitamins and those on a placebo.

Taking vitamin supplements does not improve health and may increase the risk of premature death, according to media reports.

A review of 67 randomised trials found that taking the supplements vitamin A, vitamin E and beta-carotene could lead to premature death.

The evidence for vitamin C and selenium suggested that the pills did not increase the risk of death, but there was no benefit in taking the pills compared with a placebo.

The researchers concluded that the current evidence does not support the use of antioxidant supplements in a healthy population.

There is no suggestion from the review, however, that a diet rich in natural sources of antioxidants could be damaging to health, say the papers.

Around 12 million people in Britain are taking vitamin supplements fuelling a £330 million industry.

What is the research?
The reports are based on the findings of a Danish study into the impact of antioxidant supplements on mortality rates.

A search of published literature and other studies held by manufacturers identified 815 trials. But only 67 were considered to be adequately run randomised controlled trials. These included 232,550 people aged an average of 62 years.

Twenty-one of the trials focused on the use of supplements in healthy individuals, while the rest tested patients with a range of diseases. Trials including children, pregnant women or patients with acute conditions, such as cancer, were excluded.

Antioxidant supplements were found to increase the risk of premature death in 47 trials.

Overall, antioxidant supplements were linked to a 4 per cent increased risk of death compared with placebo.

But when antioxidants were assessed separately, the researchers found that vitamin A was linked to a 16 per cent increased risk of premature death. For beta-carotene there was a 7 per cent increased risk of death and for vitamin E a 4 per cent increased risk of death.

The use of vitamin C or selenium did not increase the risk of death but showed no beneficial health effects compared with placebo.

Antioxidant supplements could lead to early death by eliminating too many free radicals, suggest the researchers. This could interfere with some essential defensive mechanisms such as apoptosis and detoxification, they say.

What do the researchers say?
Lead author Dr Christian Gluud, from the centre for clinical intervention research at Copenhagen University, called for better regulation of antioxidant supplements.

‘If a patient can eat a healthy, varied diet, then there is no need to take vitamin supplements. According to our results this may even be harmful.

‘Based on our results, as well as the results from other studies, it seems that these supplements might increase the progression of cardiovascular diseases and certain cancers.

‘It seems that the increased mortality comes from an acceleration of disease progression rather than from the development of new diseases.’

The team has not looked at whether a diet rich in natural antioxidants could be harmful to health but it would be good to conduct some large scale trials into this, said Dr Gluud.

What do other experts say?
Anne Sidnell, nutrition scientist at the British Nutrition Foundation, said: ‘The findings of this study are in line with other studies that have shown that antioxidants have no health benefits when consumed as supplements rather than through food.

‘Our bodies are designed to take in the correct amounts of nutrients from food, but there is a danger of overdosing when using supplements.’

There may be occasions when supplements are needed, such as vitamin D supplements for the elderly or folic acid for pregnant women, but overall a balanced diet is the best way to stay healthy, she added.

But Pamela Mason, nutritionist and spokeswomen for the Health Supplements Information Service, said: ‘Trials using antioxidant supplements have shown inconsistent findings and yet another review or meta-analysis is not going to tell us anything at this stage.

‘Antioxidants, including these noted in the Cochrane review, are essential for health and UK national dietary surveys have shown that some people have poor intakes of such nutrients.’

Antioxidants are not ‘magic bullets’ and were never intended for the prevention of chronic disease and mortality but for health maintenance, she added.

Popping vitamin pills ‘like sweets’ could seriously damage your health, warn experts

HEALTHY people who take vitamin supplements were last night urged to be careful after research suggested they may do more harm than good.

Welsh health experts advised people to meet their nutritional needs by eating five portions of fruit and vegetables a day.

There were also calls for tighter regulation of the sale of vitamins and minerals, which the public can buy “like sweets”, according to dietary advice groups.

The warning comes after researchers found that people who take antioxidant supplements, including vitamins A and E, to try to keep diseases such as cancer at bay, could in fact be interfering with their natural body defences and may be increasing their risk of an early death by up to 16%.

About 12 million Britons supplement their diets with vitamins and the industry is worth about £330m a year.

Paul Walker, chairman of the National Public Health Association Cymru, said: “We all need vitamins up to a certain level, but there is a misconception that taking more must be good for you.

“The evidence shows that this isn’t true. Having too much does no good and, in fact, could do people harm.

“The key is to have a very varied diet with at least five portions of fruit and vegetables per day.

“More regulation of this industry is probably required.”

Antioxidants, including vitamins A, E, C and beta-carotene and selenium, are said to mop up disease-causing compounds called free radicals. It is this action that researchers say may cause problems with the defence system.

The research by Copenhagen University, released by the influential Cochrane Library, applied only to synthetic supplements and not to vitamins that occur naturally in vegetables and fruit.

Researchers carried out a review of 67 studies on 230,000 healthy people and found “no convincing evidence” that any of the antioxidants helped to prolong life expectancy but some “increased mortality”.

They found that vitamin A supplements increased the risk of death in healthy people by 16%. Taking beta-carotene was linked to a 7% increased risk, while regular users of vitamin E supplements increased the risk of an early death by 4%.

Although the review found no significant detrimental effect caused by vitamin C, it found no evidence that it helped ward off disease. Millions take it in the hope of avoiding a common cold.

Goran Bjelakovic, who led the review, said: “We could find no evidence to support taking antioxidant supplements to reduce the risk of dying earlier in healthy people or patients with various diseases.

“If anything, people in trial groups given the antioxidants beta-carotene, vitamin A and vitamin E showed increased rates of mortality.”

Catherine Collins of the British Dietetic Association said: “This study is deeply worrying and shows that there should be more regulation for vitamins and minerals.

“The public can buy vitamins as easily as sweets. They should be treated in the same way as paracetamol with maximum limits on the dosage.”

Camille Clarke, a naturopathic nutritionist, based at the Natural Health Clinic in Cathedral Road, Cardiff, backed calls for tighter controls.

“It [the industry] needs to be regulated, vitamins are too freely available,” said Camille, who urged people to opt for naturally- occurring vitamins.

“People read things in magazines and they are taking huge amounts of vitamins and minerals but have a terrible diet.

“There’s no point in taking vitamins if you don’t have a healthy diet. You should only take them if you have a health problem and only for a little while.”

Denise Parish, a lecturer in dietetics at the University of Wales Institute, Cardiff, and a state registered dietician of 14 years, said: “As a general rule there is no evidence to say taking vitamins is of any benefit. Actually eating the foods that contain them is the best way of getting antioxidants.”

She said the only people who should take vitamin supplements are those who have particular health problems or pregnant women who are advised to take folate.

The chief medical officer for Wales, Dr Tony Jewell, said: “A good balanced diet which includes fresh fruit and vegetables will always provide individuals with the vitamins that they need.

“We would always advise people not to rely on such supplements as their primary source of vitamin intake.”