At some point in the next year, one in three of us will turn to pills to supplement our diet. But, apart from the still-sprightly 93-year-old Dame Barbara who pops around 60 pills a day, where is the evidence that vitamin pills do us any good?
In America, the vitamin supplementation debate is in danger of raging out of control. Manufacturers, feeding off a health-crazy market, pledge hundreds of potions and pills as protection against illness and disease.
In response to the deluge of claims made on behalf of food supplements, the United States Food and Drug Administration has implemented new laws stipulating that claims printed on labels must be supported by "significant agreement among qualified experts".
In Britain, the Department of Health's advice is that all our vitamins and nutrients can be obtained from a balanced diet. Last month, a report on the effects of diet on health by the Government's Committee on Medical Aspects of Food Policy (Coma) concluded: "We do not recommend supplementation with concentrated or purified preparations ...as long-term safety and efficacy in a variety of population groups has not been demonstrated."
Earlier this year, two reports in the prestigious New England Journal of Medicine questioned the value of vitamin supplementation.
The first, the most thorough trial so far, looked at 29,000 middle-aged male Finnish smokers. It found that the smokers had an increased risk of lung cancer while taking vitamin E and beta carotene (an antioxidant nutrient and source of vitamin A).
The results also showed higher rates of heart disease among those taking beta carotene. The authors concluded that these vitamins might "have harmful as well as beneficial effects".
The second study looked at 864 patients suffering from cancer of the intestine. They were given doses of vitamins C, E, and beta carotene. Again, the results failed to support the use of supplementation. The researchers concluded: "Other dietary factors may make more important contributions to the reduction of the risk of cancer associated with a diet high in vegetables and fruits."
Under British law, companies cannot make direct medicinal claims on behalf of vitamins and supplements, which are classified as foods. However, this did not prevent unsubstantiated claims about boosting children's IQ and curing arthritis a few years ago.
Nevertheless, the vitamin and food supplement market is one of those rare phenomena - ever since the sale of the first vitamins, the market has expanded. Last year it was worth £258m, an increase of 12 per cent on the previous year. A spokesperson for Sanatogen, the vitamin and food supplement brand leader, said: "We expect the market to continue to grow at the same rate this year and the year after that."
Sue Dibb is co-director of the Food Commission, an independent food watchdog. She believes manufacturers are preying on people's fears: "They are pandering to a neurotic middle class. The people who most need to improve their diet can't afford to buy these supplements."
And results from an investigation carried out by the commission show that the body is unable to properly absorb many vitamin and mineral pills. The commission is pressing the Government to insist that all food supplements be manufactured to the same standard as that required for medicines.
The one thing scientists can agree on is that we can get vitamins and nutrients by eating fruit and vegetables. Even the Proprietary Association of Great Britain, which represents the vitamin and food supplement industry, accepts that vitamins should only be used to supplement the diet.
But the Government's message is still the same. A DoH spokesperson says: "We take a fairly strong line on this. As food is the best way to obtain the body's requirements, supplementing your diet with vitamin and mineral pills is rarely necessary."
Professor Michael Marmot,who chaired this month's report by Coma on nutritional aspects of cardiovascular disease, says: "There is reason at least to be wary before recommending to everybody that they go and start popping vitamin pills. There may be something about vegetables that is protective over and above the particular vitamin."
Catherine Rice-Evans is professor of biochemistry at Guy's Hospital, London, where she is studying the effects of antioxidants on heart disease. She believes supplementation is necessary because the body can't get enough of some vitamins from a normal diet.
"There are populations in Scotland which don't eat vegetables from one year to the next. And that is one of the reasons why the incidence of heart disease in Scotland is one of the highest in the world.
"For those people who are eating five to nine portions of fruit and vegetables a day, I would agree with Professor Marmot, that supplementation is rarely necessary, but many people aren't or are genetically predisposed to heart diseases."
Professor Rice-Evans believes we mustn't be too blase about applying the Government statements to the whole population. She says there have been more than 200 studies looking at the relationship between eating fresh fruit and vegetables and heart diseaseand some types of cancer. Most of these have shown the relationship to be beneficial.
"The results of the Finnish trial do not surprise me," she says. "They had been exposed to smoking for so long that a few years taking vitamin pills could not have significantly affected the incidence of lung cancer."
Professor Rice-Evans admits that there are many small [vitamin and food supplement] companies which bring the market into disrepute by making exaggerated claims. "But generally the others do good by educating the public - and they could do more."
Maurice Hanssen is president of the Health Food Manufacturers' Association and has written 27 books on health and food, including the million seller E for Additives.
He believes that research into antioxidant nutrients shows that in northern Europe there is little chance of getting all our vitamins from our diet.
He says: "Eating five to seven portions of fruit and vegetables a day - excluding potatoes - as recommended in the Coma report, is not achievable by normal people."
But Ms Dibb argues: "We have to look at supplementation sceptically because there is still no evidence that you are getting the full protective benefit that you would get by eating real food."
And while the nutrition experts continue to disagree, politely, eating healthily becomes ever more confusing.Reuse content