Unlike F.D.A. labeling rules, which forbid claims that supplements can treat or prevent disease, the F.T.C. guidelines allow such claims in advertisements, provided that the manufacturer can substantiate them.

The supplements have been used for years by veterinarians in the U.S. and abroad to treat animals for symptoms of osteoarthritis.

Dr. Bill McGhee, a clinical pharmacy specialist at Children's Hospital in Pittsburgh, said that 25 to 30 percent of people with liver disease take supplements to treat themselves.

Under F.D.A. rules, manufacturers may not claim that their supplements can treat or prevent disease.

Find vitamins or supplements to treat:

Makers of dietary supplements cannot legally say that dietary supplements can diagnose, cure, treat, or prevent disease.

Thus manufacturers could say that their supplements can treat morning sickness or leg swelling in pregnancy.

Ask your doctor whether you should take supplements to treat these deficiencies.

Some people take supplements of L-tryptophan to treat sleeplessness, depression, premenstrual syndrome, stress and other problems.

I read online that a supplement can treat my dogâ s illness.