(HealthDay News) -- More than half of Americans take a dietary supplement of some kind, the Cleveland Clinic says.

But all supplements aren't safe and effective. The clinic offers this primer:

• There's no better substitute for a healthy, balanced diet, which can provide most healthy people with all of the nutrients they need.
• Supplements are a good option for people who can't get enough of certain needed nutrients through diet. Pregnant women, athletes and vegetarians are prime examples.
• Too much of a good thing can cause serious health problems. Be sure not to exceed the recommended daily amount of any supplement.
• Supplements aren't regulated by the U.S. Food and Drug Administration, so it's up to consumers to carefully check supplement labels to be sure what they're taking.