Even with the new regulations, if they are enforced, supplements still have fewer controls than drugs -- an important health consideration for the 150 million Americans who take these products.
"Most people don't realize that dietary supplements can have side effects, just as there are potential side effects to prescribed medications," says Dr. Nieca Goldberg, medical director of the New York University women's heart program. "Because they are chemicals that are added to your body, I think they should be subjected to the same rigorous evaluation as prescription pharmaceuticals."
A drug that the FDA suspects is unsafe can be removed from the market until the manufacturer demonstrates its safety. However, for diet supplements, the onus is on the FDA to prove a product is unsafe before it can be pulled from shelves.
In 2005, after reports of more than 155 deaths were linked to the dietary supplement ephedra, the FDA prohibited its sale. Some experts think that the FDA reacts too slowly when it comes to the safety.
"In many countries -- Germany, in particular -- nutrient supplements are regulated like drugs," says Dr. David Katz, director of the Prevention Research Center at Yale University School of Medicine. "The U.S. has lagged behind in that area."
Though most experts agree that the regulations will increase the likelihood that supplements will be of high quality, some raise the issue of whether these products -- which claim to remedy everything from decreased sex drive to damaged joints -- actually work.
"Nothing here deals with the question of efficacy, which is a shame," said Dr. Jerry Avorn, chief of pharmacoepidemiology and pharmacoeconomics at Brigham and Women's Hospital. "Knowing you have pure and well-made useless crap is a little better than having impure useless crap, but not by much."
Some doctors have been sending their patients to Web sites like www.consumerlab.com to determine if a supplement is of reliable quality.
"It would be as if you could learn about car safety through a Consumer Reports subscription, but there were no federal standards for auto safety," said Yale's Katz.
"We really need both -- for cars, and supplements," he said. "For cars, we have both -- but for supplements, until now, we have not. The new FDA ruling narrows the gap."