Taking vitamin E supplements may make bones old and frail before their time, Japanese researchers say. A study found that animals fed on a diet supplemented with the vitamin had bones 20 per cent weaker than those that ate normally. More worrying is that the effect was seen after just eight weeks, the Daily Mail reported. The scientists behind the research said that given the popularity of vitamin E supplements, a larger study on people is now warranted. The vitamin, which occurs naturally in cereals, nuts, olive oil and egg yolks, is credited with helping hold back the hands of time by 'fighting ageing from within'. Benefits are said to include cutting the risk of heart disease, cancers and cataracts, as well as helping keep the mind sharp into old age and the skin supple. One of the world's most popular supplements, it is taken daily by hundreds of thousands, if not millions, of Britons. In the US, more than one in ten adults take vitamin E tablets. The latest study looked at the effect of alpha-tocopherol, the most common form of the vitamin, on bone strength. Bone is constantly changing, with old bone broken down and new bone being built. Osteoporosis occurs when old bone is broken down by the body far more quickly than it is replaced. In the Japanese study, mice genetically modified to have low levels of the vitamin in their blood, grew bones that were extra-thick. This was found to be due to them being poor at breaking down old bone, rather than good at making new stuff. When vitamin E was added to the animals' diet, their bone density returned to normal. In another experiment, giving normal mice alpha-tocopherol vitamin E supplements at doses equivalent to those taken by people, led to their bones thinning by a fifth in just two months. The same result was seen in rats. Researcher Dr Shu Takeda, of Keio University in Tokyo, called for a larger study on the vitamin's effect on human bones. "There is nothing to worry about if you are getting plenty of vitamin E from your diet but those taking high doses of the nutrient in supplements need to bewary," said Professor Helen MacDonald, an advisor to the National Osteoporosis Society. "You have to remember this research was carried out on animals and findings in humans can be very different. But more research is needed," Dr Takeda added. Details of the study appeared in the journal Nature Medicine.