Now, worries about one particular vitamin, B6, have caused the Government to act. Large doses - and we are talking gobstopper sizes here - can cause nerve damage. The ministry of agriculture is to introduce legislation limiting the dose level to a modest 10mgs for general sale and up to 49mgs from pharmacies. Doses of 50mgs and above will be available only on prescription. In future, all pills will have to carry a warning label about the risks of exceeding a 10mg dose a day.
The outrage that has greeted this apparently modest change is remarkable. Lobbyists on behalf of the vitamin manufacturers accuse the Government of choosing a soft target to establish its credentials as an administration that cares about public health. They also fear that this may be a harbinger of a more concerted assault on the lucrative herbal medicine and food supplement markets.
The reaction is in marked contrast to that which greeted last week's Government announcement of tough new controls on Britain's most popular painkillers, paracetamol and aspirin, limiting the size of packs on general sale, in the hope of cutting the 140,000 hospital admissions for overdoses each year. That proposal met with hardly a murmur of protest, despite the fact that the smaller pack sizes will mean significantly higher prices for the millions of people who buy the drugs each week.
Vitamin B6 is found in a wide variety of foods, including cereals, potatoes, milk, meat and beer, and is essential for breaking down protein for use by the body. The recommended daily requirement is 1.6mgs for adult women and 1.4mgs for adult men. Healthfood shops recommend larger doses for treating conditions such as premenstrual syndrome, which can only be achieved by taking supplements. A 10mg supplement is more than five times the daily recommended dose and should be enough to deal with a sackload of protein. Vitamin B6 is a constituent of many multivitamins and is available in doses up to 200mgs.
Jeff Rooker, food safety minister, insisted that he was acting on the best scientific advice. "Vitamin B6 is an essential component of people's diets. But, like many things, too much can be harmful," he said. This apparently innocent remark was seized on by Maurice Hanssen of the Council for Responsible Nutrition, set up to represent vitamin manufacturers, who pointed out that too much of anything is harmful, saying, "100 grams of salt will kill you".
So it will, but no one has claimed 100gms of salt would do you good. Rooker's point was that vitamin retailers were suggesting that 100mgs or 200mgs of vitamin B6, or even more, could be used to treat conditions as diverse as menstrual problems, acne and sickle-cell anaemia.
A new survey for the Council shows that one million people are estimated to take B6 regularly, with an average dose being 50mgs to 100mgs a day, although some people take more. One in five users are men. Concern had originally been raised by the Consumers Association, which was worried by the high levels of the vitamin in some dietary supplements. One contained 100mgs in a single dose, more than 50 times the daily amount required to maintain normal bodily function and like swallowing a small boat.
The Government asked the Committee on Toxicity of Chemicals in Food to examine the evidence. It looked at a series of human and animal studies and concluded that although no one study was conclusive, the findings were generally consistent and pointed to evidence of harmful effects when the vitamin is taken in doses of 50mgs or more for long periods of months or years. The effects included numbness, tingling and pins and needles. There is general agreement on both sides of this dispute that at very high levels of 1,000mgs, vitamin B6 can cause nerve damage of the kind noted by the committee on toxicity. The argument is about the threshold at which that damage starts.
A spokesman for the ministry of agriculture, bemused by the vehemence of the opposition, stressed that the Government was not banning the vitamin nor arbitrarily choosing to restrict its sale, but was merely acting on the advice of independent scientists. "If people think they may be doing themselves some good [by taking large quantities of B6], when in fact they may be doing themselves harm, then we have a responsibility to tell them about it," he said.
The vitamin lobby, however, questions both the Government's motives and the quality of the science on which the decision is based. It says the new Government is keen to be seen as the consumer's champion and is bending the evidence to suit its public relations needs. Derek Shrimpton, a nutritionist and advisor to the Council for Responsible Nutrition, says: "Here we have a new ministry that wants to show it is serious about consumer safety. There is a political advantage to finding something to make a song and dance about."
Shrimpton says that only one study, by Dr Katherina Dalton, has suggested evidence of harm at a dose level of 50mgs and that has been "completely discredited". Another study showing harm at 200mgs was "very dubious". "A level of 500mgs is where you start to get a problem," he said.
Consumers will have to make up their own minds about these competing claims. But the strength of the industry's response indicates that they fear more could be at stake than a few bottles of vitamins. Holland and Barrett, the healthfood chain with more than 410 outlets in Britain, made profits of pounds 7.8 million on turnover of pounds 90.6 million last year. It is set to be sold to US firm Vitamin World but it is unclear whether the Americans have taken account of the new restricitions on B6 which features in 40 of Holland and Barrett's most popular lines and contributes more than pounds 2 million to the chain's revenues.
There is also a wider question: whether vitamin supplements are worth taking at all. Many doctors believe that they are a waste of time and money because any excess over what the body needs is excreted - as expensive urine.Reuse content