When studies came out showing that women with breast cancer tended to have low levels of vitamin D, doctors hoped that boosting vitamin D in women could reduce their breast cancer risk.

But in a study of more than 36,000 women, those taking daily supplements of vitamin D had the same risk of developing breast cancer as those taking a placebo.

People with low levels of vitamin D tend to have a higher risk for a wide range of diseases, from cancer to diabetes and heart disease.

But the question remains: can we make people healthier by boosting their consumption of vitamin D?

Researchers tested the theory in a large study of more than 36,000 older women, half of whom took daily supplements of vitamin D for seven years while the other half took a placebo.

Results showed no differences in their odds of developing breast cancer and no difference in their colon cancer risk either.

Some experts say that women need to take even higher doses - more than the 400 daily international units used in this study - to alter their cancer risk.

Others suggest that women need to start taking the vitamin D while they are young to see any benefit.

Future research will address these claims.

In the meantime, doctors recommend that women take daily vitamin D for bone health and wait to see if any additional health benefits emerge.

Source: published in the Journal of the National Cancer Institute by researchers from the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center