Two of the most popular products in Britain’s vast health food industry come under attack today, as scientists cast doubts on the benefits of vitamin supplements and low-fat dairy products. Research published today suggests that regular consumption of a wide range of vitamin pills, taken by more than ten million people in the UK, may actually increase the risk of dying, while eating low-fat dairy products could make it harder for some women to conceive.

The vitamin study, published in The Journal of the American Medical Association, overturns earlier research suggesting that vitamins A, E and beta carotene could protect against heart disease and cancer.

But far from helping, the new study says, the evidence is that taking vitamins, either singly or as part of a multivitamin pill, actually increases mortality by 5 per cent.

The scientists, based at Copenhagen University Hospital, who carried out an in-depth analysis of research involving more than 200,000 people, conclude that the “public health consequences could be substantial”.

A second study in the journal Human Reproduction, by researchers from Harvard Medical School , indicates that the rush into low-fat foods, driven by fear of heart disease and obesity may also have consequences for fertility.

The researchers found that women eating normal amounts of low-fat dairy products stood a higher risk of failing to conceive. Their diet appears to be implicated in a failure to ovulate, which is responsible for 12 to 15 per cent of cases of infertility. Women who ate whole-fat dairy products suffered fewer cases of this form of infertility.

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