Britons are wasting their money and possibly risking their health by taking vitamin supplements, Professor Brian Ratcliffe, a leading nutritionist has claimed, according to The Telegraph.
Popular multivitamin and mineral supplements are completely pointless for the majority of people on a healthy diet, Professor Brian Ratcliffe argued.
He added that topping up on vitamins could occasionally prove dangerous especially if you already ate a healthy diet.
Safe levels of vitamin A can easily be exceeded, for instance, by taking both multivitamin and fish oil supplements, Prof Ratcliffe said.
Excess vitamin A, which accumulates in the liver, led to headaches and nausea and over a long period of time increased the risk of osteoporosis, and damage to the eyes and liver which cannot be reversed.
Large doses of vitamin C - taken by many in the belief that they fight colds - may also be harmless but can also have unpleasant effects on the stomach, said the professor, an expert advisor to the Food Standards Agency.
Taking large doses of vitamins can also interefere with prescription drugs, making them more or less potent, and affect the body`s ability to absorb other vitamins and minerals.
Speaking at the British Festival of Science he pointed out that ideal vitamin intake levels varied enormously between individuals.
But he said millions of the population took vitamin supplements as part of a "belt and braces" approach to health.
"They may not be thinking very much about how much they should taking or whether they should be taking them at all," said the professor at the Robert Gordon University in Aberdeen.
"People who take multivitamin supplements are probably just wasting their money and boosting the profits of vitamin companies.
"With the sort of multi-vitamin mix that`s readily available, if you`re taking one of those on top of your normal vitamin intake you`re unlikely to push yourself beyond safe levels.
“There is a chance you could be dabbling in areas where there is a potential for harm.
"It`s a whole new area. We haven`t had a significant proportion of the population taking all these supplements before.
"They should certainly speak to a doctor or dietician or nutritionist. I think they`d be better off investing time in trying to choose healthy items for their diet rather than thinking you can bolt on that safety margin by just taking a supplement."
Vitamin C was one of the most abused vitamins, said Prof Ratcliffe.
People often had the mistaken belief that heavy doses of the vitamin staved off colds, he said.
In fact research evidence suggested that vitamin C might shorten the length of a cold but could not prevent one.
"If you take a megadose of vitamin C, say 1.5 grams, 50 per cent of that will go straight through you and down the toilet, and make you feel uncomfortable on the way," said the professor.
"A further amount, probably a quarter or third, will disappear in the urine. You`ve taken this massive dose of vitamin C and the majority of it will go down the toilet pan."
Vitamin C is found naturally in citrus and soft fruits, leafy green vegetables, kidney and liver.
Vitamin A was another example of one micronutrient that was potentially harmful, said Prof Ratcliffe.
"You only need to be taking a small amount more than you should be," he said. The safety limit for vitamin A can be passed if you take a multivitamin supplement plus fish oil."
Dairy products, fortified margarine and liver are high in natural vitamin A and pregnant women in particular are warned against consuming too much.
Smokers have been warned against taking too much betacarotene, found naturally in carrots and other brightly coloured foods, as high doses have been linked with cancer in this group.
The number of Brits popping supplements has been in steady decline since 2007, with the total number of users falling from 43 per cent in
Sales number of single and multi-vitamin pills fell from £121 million in 2007 to £118 million in 2008 and expected to fall to below £100 million within the next six years, Mintel predicts.
Improved education on diet and nutrition has been a root cause of the slump in pills and return to real food.By Richard Alleyne, Science Correspondent, The Telegraph