Studies have shown that people over the age of 50 often believe that taking vitamin D supplements can lead to stronger bones and prevent osteoporosis in patients who lose bone density as they age, leading to weaker bones. Weak bones are prone to fractures. A common preventive measure is to take calcium tablets and vitamin D supplements. Vitamin D facilitates the absorption of calcium in the body. However, vitamin D is not often found in food, except in concentrated foods like most milk. The body can produce vitamin D in the presence of sunlight, and although calcium is necessary for strong bones, the safety of calcium supplements has been questioned. Recent evidence suggests that calcium supplements may increase the risk of heart attack when used with or without vitamin D. Dr. Reid and colleagues collected 23 previous studies on vitamin D and bone mineral density and then reanalyzed their findings. A total of 4,082 subjects with an average age over 50 and 92% of whom were women were included in the study. Each study measured bone mineral density in one to five areas of the body (e.g., spine, hip and forearm). A total of 70 separate site-specific BMD measurements were taken before and after taking vitamin D supplements, of which six showed a benefit from the supplements, two showed bone loss, and the rest showed no benefit from vitamin D. The researchers found that any dose of vitamin D supplementation did not change bone density much. Dr. Reid said it was surprising that so many detailed studies did not show a benefit of vitamin D supplementation on bone density, even when the subjects in the study had fairly low baseline levels of vitamin D. He found the available evidence – that calcium supplements can increase the risk of cardiovascular events – to be compelling. Therefore he does not recommend that people take calcium supplements unless their doctor recommends it. Dr. Reid suggests that people interested in making lifestyle changes to improve bone health should get enough calcium in their diet, as well as some regular exercise and sun exposure without sunburn, rather than relying on supplements. However, some people do need to consider taking vitamin D supplements. People who have been housebound for a long time due to old age, black people who live in equatorial zones, and people who are used to wearing veils are all in need of supplements. Paul Coates, director of the Office of Dietary Supplements at the National Institutes of Health, agrees that many people in the United States take vitamin D supplements, although they are fewer in number than those who take multivitamins and calcium supplements. Vitamin D may have other benefits, but Dr. Coates said there is not enough evidence to make any recommendations or suggestions beyond those for maintaining bone health. Recent studies are analyzing the relationship between vitamin D and the prevention of cancer and type 2 diabetes.