CHICAGO, Ill. -

A new study of recently revised vitamin D guidelines finds that millions of Americans may no longer need to take the supplements.

Researchers at Loyola University say, under recent recommendation from the Institute of Medicine, nearly 80 million Americans no longer need additional vitamin D.

The 2010 guidelines said people get enough vitamin D if their blood levels are at or above 20 nanograms per milliliter.

Older guidelines indicated that levels about 30 were necessary.

Vitamin D is critical for healthy bones, but too much can damage your kidneys and heart.

When in doubt, you should always check with your doctor to see what your vitamin D level is, and whether you need to take additional supplements.