Vitamins and supplements: What you need to know

A new Centers for Disease Control and Prevention report finds the use of some dietary supplements is on the rise. More than half of all U.S. adults - a whopping 53 percent - are popping vitamins and minerals. Americans spend $26 billion a year on them. But are they worth it?

CDC: Half of US adults take vitamins, supplements

Many people in the U.S. take calcium, vitamin D and some supplements, CBS News Medical Correspondent Dr. Jennifer Ashton explained on "The Early Show."

But are they making us healthier?

Ashton said the data is conflicting.

"Some say yes. Some say no," she said. "There's no question ideally we should get these ingredients from our diet. But you know, as well as I do, the American diet is really lacking, so probably the people who need these supplements most are usually not the ones taking them, unfortunately."

Ashton said people need to be aware of the ingredients in their vitamins and supplements.

"They need to talk to their doctor about these ingredients, because anything that's found on a shelf, you don't need a prescription for it," she said. "That's what people are usually drawn to in terms of taking."

Women take more supplements than men do, according to the study. Ashton said there are some supplements that women should take, including folic acid.

"For a woman of reproductive age (take folic acid)," she said. "You have to remember in this country half the pregnancies are unintended. That doesn't mean undesired. And when you talk about folic acid, women need 400 micrograms a day. You need to have that in your blood system months before conception to prevent neural tube defects. And then calcium. Young kids, teenagers, women after menopause, very important (for strong bones.)"

However, vitamins and supplements can be harmful in some cases.

"We tend to think if a little is good, more must be better. Not true," Ashton said. "These vitamins can have toxicities. They can interact with other drugs. If you're going to take a vitamin or supplement, you want to something for something called a USP label, which is usually stamped on the more reputable brands of vitamins. Tells us about the purity and contents, so you know what is on the label is in the pill."

However, getting vitamins from your diet, Ashton said, is the best route.

She said, "If your diet is lacking, sure, in moderation, these supplements can be very good. You want to have a nice, healthy lifestyle. "

Your doctor, Ashton said, should always know if you're taking a supplement or vitamin.

If you are taking vitamins or supplements, Ashton advised keeping them in place that's cool and dry.

"Not in the places most people put them. Not in a moist bathroom, not in a hot kitchen," she said. "... A lot of those plastic containers are very helpful."

She added, "And they don't last forever."