The US Food and Drug Administration (FDA) has relaxed guidelines for the sale of herbal supplements. Its decision has opened the way for manufacturers of vitamins, herbs, and dietary supplements to market their products for conditions such as morning sickness, hot flushes, and memory loss in ageing without first proving that they are safe or effective.

The decision marks the latest in a series of legal and regulatory victories for the dietary supplement business, which has been growing since Congress passed a law in 1994 that severely restricted the FDA's authority to regulate it.

Under the new law manufacturers of dietary supplements can make claims about how their products affect the structure or function of …