New York, Aug 10 (IANS): Are you among those who gulps down a multivitamin every morning, probably with a sip of water? It may be of no use, finds a study.

While multivitamins aren't helpful, at least they're not harmful. But the money people spend on them could be better spent on purchasing healthy foods, according to Dr. Pieter Cohen, an associate professor of medicine at Harvard Medical School.

Researchers analysed 84 studies involving nearly 700,000 people. Their review, published in JAMA, found little or no evidence that taking vitamin and mineral supplements helps prevent cancer and cardiovascular disease that can lead to heart attacks and stroke, nor do they help prevent an early death.

"Most people would be better off just drinking a full glass of water and skipping the vitamin," said Cohen, an expert in dietary supplementAresearch and regulation.

"We have good evidence that for the vast majority of people, taking multivitamins won't help you," he added.

There are some exceptions, however. Highly restrictive diets and gastrointestinal conditions, or certain weight-loss surgeries that cause poor nutrient absorption, are examples of reasons why a multivitamin or individual vitamins might be recommended.

A daily vitamin D supplement may be necessary when a person gets insufficient sun exposure. Your doctor may recommend an iron supplement if you have a low red blood cell count (anaemia).

Surveys suggest people take vitamins to stay healthy, feel more energetic, or gain peace of mind. These beliefs stem from a powerful narrative about vitamins being healthy and natural that dates back nearly a century.

"This narrative appeals to many groups in our population, including people who are progressive vegetarians and also to conservatives who are suspicious about science and think that doctors are up to no good," Cohen said.

Vitamins are very inexpensive to make, so the companies can sink lots of money into advertising, he noted. But because the FDA regulates dietary supplements as food and not as prescription or over-the-counter drugs, the agency only monitors claims regarding the treatment of disease.

For example, supplement makers cannot say that their product "lowers heart disease risk". But their labels are allowed to include phrases such as "promotes a healthy heart" or "supports immunity", as well as vague promises about improving fatigue and low motivation.

"Supplement manufacturers are allowed to market their products as if they have benefits when no benefit actually exists. It's enshrined into the law," Cohen said.

It's wise to note the legally required disclaimer on each product: "These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease," he advised.