Why vitamin E pills could risk weaker bones Its health benefits are said to include reducing the risk of heart disease, cancers, cataracts and age-related mental decline, but the evidence for such claims is patchy. The new research focused on bone "remodelling" - the maintenance of bone by balancing its formation and breakdown. When bone is broken down, specialist osteoclast cells cause its minerals to be released and recycled into the body in a process called "resorption." The study suggests that while vitamin D promotes bone generation, alpha-tocopherol vitamin E performs the opposite role. Researchers led by Dr Shu Takeda, from Keio University in Tokyo, found that genetically modified mice with low blood levels of the vitamin developed excessively high bone mass. This was found to be due to lower levels of bone resorption, rather than greater bone formation. When vitamin E was added to the animals' diet, their bone density returned to normal. Normal mice given alpha-tocopherol vitamin E supplements at doses equivalent to those taken by humans showed a 20 per cent reduction in bone mass after eight weeks. The same result was seen in rats. However, the effect did not occur when animals were given the less common delta-tocopherol form of vitamin E, which showed it had nothing to do with antioxidant properties common to all versions of the vitamin. The findings are published in the latest online edition of the journal Nature Medicine. Dr Takeda's team found that alpha-tocopherol stimulated the fusion of osteoclast precursor cells - the first step in osteoclast formation. The researchers wrote: "In summary, we show that vitamin E stimulates bone resorption and decreases bone mass by inducing osteoclast fusion. Moreover, we provide evidence that serum vitamin E is a determinant of bone mass. Given the widespread use of vitamin E, and especially alpha-tocopherol, as a supplement in humans, a larger, controlled study that addresses its effects on human bone is warranted. Several previous studies had indicated beneficial effects of alpha-tocopherol on bone, probably due to its antioxidant properties, the scientists acknowledged. But they added: "Most of these studies used a small sample size and were not well controlled."