Manufacturers of dietary supplements will need to prove that what they describe on the label is actually in the bottle under new regulations announced by U.S. regulators on Friday.

Makers of supplements such as vitamins and herbal pills will have to test all ingredients in their products, the U.S. Food and Drug Administration said.

The new rule is meant to address concerns that supplements could be contaminated or lack ingredients stated on the label, such as offering less vitamin C than claimed.

"This rule helps to ensure the quality of dietary supplements so that consumers can be confident that the products they purchase contain what is on the label," FDA commissioner Andrew von Eschenbach said in a statement.

Manufacturers will be required to evaluate the identity, purity, strength and composition of their supplements. They will also need to check for contamination from toxins, bacteria, pesticides, glass and lead, as well as improper packaging and labels.

Under the new standards, inspectors will check for compliance at the manufacturing plant. The regulations also include requirements for record keeping and handling of complaints from customers.

The requirements are effective Aug. 24, and apply to domestic and foreign companies that manufacture, package and label supplements for sale in the U.S.

Companies with more than 500 employees have until June 2008 to comply, while smaller companies will have an extra year. The smallest companies employing fewer than 20 employees will have to comply by June 2010.

Bar raised far enough?

Most companies already test their raw ingredients, said Steve Mister, president and CEO for the Council for Responsible Nutrition, a trade association representing about 65 manufacturers in the $22-billion US industry.

"This raises the bar so that all have to comply," Mister said.

Companies can ask to be exempt from testing of all of their ingredients, or can provide documents showing less-frequent testing would still assure quality.

It will still be too easy for unsafe supplements to get on the market, said Dr. Sidney Wolfe, director of Public Citizen's Health Research Group, a consumer watchdog.

"You still don't have to show the product is safe. You don't have to prove it works," said Wolfe, who has testified to the U.S. Congress about the safety of dietary supplements.

Health Canada's guidelines for natural health products aim to clear up confusion about conflicting health claims and warnings about mixing natural products with other medicines. The department's Natural Health Products Directorate regulates the industry.

Manufacturers of supplements in Canada must obtain a product licence from Health Canada, which assesses the product to determine if it is safe, effective and of high quality.

With files from the Associated Press