BAKERSFIELD, Calif. -- A large study of women at risk for heart disease found no differences in cancer rates among those who took a daily B-vitamin supplement and those who took a placebo.

In the past, studies have shown that people with low levels of vitamin-B often have a greater risk for certain cancers.

But new research has suggested that simply increasing vitamin-B levels with a daily supplement does not lower the risk for cancer.

Doctors from Brigham and Women's Hospital studied more than 5,400 women at high risk for heart disease who were taking either a daily supplement of vitamins B12, B6 and folic acid -- or a placebo.

The women took the pills for more than seven years but did not lower their overall risk for heart disease or for cancer.

However, researchers did find some possible benefit for older women. In those over 65, there were 25 percent fewer cancers among women taking supplements.

Experts said the findings will require confirmation.