(CBS) A new study of recently revised vitamin D guidelines found millions of Americans may no longer need to take the supplements.

That might be confusing for patients who previously required extra vitamin D.

Doctors put 63-year-old Allegra Lubicz on vitamin D supplements after blood tests showed low levels. “I’m taking it at least for two years,” she says.

But now, a new study shows she doesn’t need to take it anymore.

"The deficiency of vitamin D is not as prevalent as we thought prior to this study, which is good news,” Dr. Albert Levy, a family doctor at Beth Israel Medical Center,” says.

Researchers at Loyola University say under recent recommendations from the Institute of Medicine nearly 80 million Americans would 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 millileter. Older guidelines indicated levels above 30 were necessary.

But some doctor groups don't agree with the new guidelines and are still prescribing doses of vitamin D under the old guidelines.

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

Dr. Albert Levy says a balanced diet and a little sun can help maintain vitamin D levels.

Lubicz is taking her doctor's advice. “That is a good thing –to have one pill less,” Lubicz says. But she says she'll let her doctor know if she starts to feel different without it.

Patients should talk to their doctor if they're feeling fatigued or tired because that may be a sign of low levels.Vitamin D Guidelines Changing