Scientists have uncovered a new worry about some of the most popular herbal remedies: the possibility that they could cause infertility, or genetically damage sperm. Many women who are pregnant or trying to conceive carefully avoid taking prescription and even over-the-counter medications for fear they could endanger their chances of a healthy pregnancy.

But herbs and other dietary supplements are advertised as "natural," with the implication that they're safe, non-drug remedies. In fact, many powerful prescription drugs were derived from plants, and many of the herbs sold in health-food stores and supermarkets also can have powerful, medicine-like actions - and side effects.

The new study by researchers at Loma Linda University suggests that the side effects of some of popular herbs - St. John's wort, echinacea and ginkgo - could include blocking conception. The study also uncovered suggestions of genetic damage to sperm, raising questions of whether such changes could cause problems for a resulting baby.

The test-tube study is not proof that couples trying to conceive should avoid taking herbs. Indeed, lead researcher Dr. Richard Ondrizek stressed that laboratory research doesn't always accurately predict what happens in humans. Nobody has ever tested actual herb users to see if the products concentrate in their sperm or eggs - the key to knowing if there's any risk.

Fertility and Sterility March 1999

Dr. Mercola's Comment:

I have not evaluated the doses they used in the study to see if they would approximate reasonable levels that one would expect to find in the body. However, I do believe the caution should be heeded. Herbs and drugs share many similar characteristics. Just because it is natural does not mean it can not harm you or a fetus. The wisest approach would be to avoid taking all herbs during pregnancy unless you have a very good reason or some expert advice to convince you otherwise.