Vitamins and other food supplements taken by millions of women may actually put them at more risk, according to a major study.
Scientists say there is little evidence the pills do any good – and in fact some could be causing serious harm.
A study involving nearly 39,000 women has found multivitamins, vitamin B, folic acid, iron, magnesium and copper all increased the statistical risk of premature death.
Nearly a third of adults in Britain take some form of dietary supplement most days and the industry is worth £675million a year.
Some of the most popular pills include multivitamins, vitamin A, C and E, iron, folic acid and calcium – which are all thought to improve long-term health and ward off illnesses.
Scientists from Finland, Norway, the U.S. and South Korea looked at the long-term health effects of common vitamin pills and minerals on 38,772 women aged 55 to 69.
Over an 18-year period the women recorded any supplements they regularly took.
The results, published in the Archives of Internal Medicine, found copper increased the risk of dying prematurely by 18 per cent. Folic acid – which pregnant women are told to take to protect their child against spina bifida – increased risk of death by almost 6 per cent, while iron raised the risk by nearly 4 per cent.
Multivitamins raised the risk by 2.4 per cent, vitamin B6 by 4 per cent, magnesium by 3.6 per cent and zinc by 3 per cent.
The scientists do not fully understand how supplements may trigger early death, but they may interfere with the body’s natural defences. They say the supplements should only be taken by patients who are malnourished and only under the supervision of a doctor. Everyone else should ensure they eat a balanced diet to get adequate vitamins and minerals.
Jaakko Mursu, from the University of Eastern Finland, said: ‘Based on existing evidence, we see little justification for the general and widespread use of dietary supplements.
‘We recommend that they be used with strong medically-based cause, such as symptomatic nutrient deficiency disease.’
The results back up a major Danish study carried out at the University of Copenhagen in 2008 which found some vitamin supplements increase the risk of dying early by 16 per cent.
Last night experts dismissed the latest findings. They claimed many patients took supplements to treat underlying health problems – for example iron for anaemia – so were more likely to die early anyway.
Dr Glenys Jones, from the Medical Research Council’s Human Nutrition Research unit in Cambridge, said: ‘This observational study is interesting, but it does not show supplement use causes women to die earlier.’
Dr Carrie Ruxton, from the Health Supplements Information Service, which provides the public with information on vitamins and minerals, said: ‘Multivitamin supplements contain a variety of essential vitamins and minerals which help those with less healthy, or irregular diets, to meet recommended intakes of nutrients, thus ensuring the maintenance of normal health and well-being.
‘The findings should be treated with extreme caution given the poor methodology and lack of reliable information about the health of participants, or the type of diets consumed.
‘As there is no credible biological reason why normal supplement use should impact on mortality, it is likely these findings represent an effect of age and ill-health rather than supplement use.’