Washington ? Supplements containing calcium and vitamin D provide only modest protection against bone fractures, according to a large government study being published today that fell short of showing a strong advantage to taking the commonly used nutrients.

The study of more than 36,000 middle-aged and elderly women – the largest ever to test the health benefits of the dietary supplements – found they help reduce bone thinning slightly and cut the risk of hip fractures among older women and those who take their supplements diligently. But the supplements did not reduce the risk of fractures as much as had been expected and provided no defense against colon cancer, as earlier research had suggested.

The findings are the latest in a series of recent major studies that have failed to find a clear association between diet, dietary supplements and health. Data from the same study last week showed that low-fat diets failed to protect women against heart disease, colon cancer or breast cancer.

“These negative results might give people the feeling that diet doesn’t matter,” said Volker Mai of the University of Maryland. “Diet does matter. The problem is we don’t know enough about diet to know what specifically matters.”

Although the study found a weaker effect for bones than expected, the researchers said it was enough to make taking supplements worthwhile, at least for older women or those at particular risk of fractures.

Although the study involved only women, there is no reason to think the findings, published in The New England Journal of Medicine, would not apply to men as well, officials said.