WASHINGTON (AP) - The Food and Drug Administration is cracking down on manufacturers of certain weight loss, body building and sexual enhancement supplements that contain potentially dangerous ingredients.

The FDA said Wednesday that some manufacturers are deceptively labeling products to hide that they contain ingredients known to cause adverse health effects. Other supplements contain ingredients that should only be available by prescription.

Dietary supplements can slip through the regulatory cracks because, unlike drugs, they do not have to be approved by the FDA before they are marketed. Manufacturers are responsible for making sure their products are safe.

In a letter to the supplement industry, the agency said manufacturers who distribute tainted products could face criminal prosecution.

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