How is the safety of herbs verified?

Essentially, there is no oversight by the Federal Drug Administration over herbal ingredients.

Anyone who can package, market and distribute products including herbal ingredients can do so, without regulation by the FDA. Thus, herbal supplement manufacturers can made all sorts of claims concerning the benefits their products will provide.

The FDA can only file a complaint after a drug has been proven to be an "imminent hazard to public safety" or an "unreasonable" health risk.

However, the Dietary Supplement Heath and Education Act of 1994 provides wide latitude for producers of herbal supplements. They can make all kinds of claims about their products as long as they do not claim that a produce can "treat, mitigate or cure a disease."

That creates a lot of leeway for marketers of supplements. For instance, instead of saying their product containing hoodia cures obesity, the producer can simply say it leads to quick weight loss. Other producers can claim that Echinacea boost the immune system and that St. John's Wort helps create a sense of well-being.