This line of reasoning sums up why herbal and vitamin supplements are so popular these days. The perception is that a substance coming from a plant or natural source must be less harmful than anything produced by the pharmaceutical industry.

Let me explain why that may not always be the case and why I have a lot of reservations. For one thing, herbal medications currently are considered nutritional supplements. As such, they do not have to be regulated by the Food and Drug Administration, which ensures that certain quality standards are met.

Without FDA regulation, there is no standardization of dosing. The therapeutic doses and toxic doses for a given substance may vary depending on the brand. There also is no guarantee that the substance in the bottle is the same as what is on the label. Or that what is in this month’s bottle is the same as next month’s, even within the same brand.

There is a perception that natural, herbal medications are gentler or less potent than prescription medications. But substances derived from nature can have serious side effects. After all, arsenic is natural, too. In some cases, herbal treatments have been known to cause severe organ damage.

They also can interact with prescription medications. As a doctor, this is one of the most frightening aspects about supplements. Many herbal companies report that there are no known drug interactions with their products. In truth, there simply is not enough research to know which supplements are safe with which prescription drugs. Given that the herbal doses can vary from one bottle to the next, you can see where trouble can arise.

Patients may be stable for months on a prescription/herbal combination, but with a slightly modified dose of one or the other, interactions can occur.

Still, nutritional supplements may have some merit. The Chinese have been using them for centuries and the German government created a commission that studies herbal medications, indicating which should be approved for therapeutic use. A lot of potential exists for use of natural substances in medicine and I think that over the next few decades we will continue to see supplements gain popularity. I also think we will find increasing numbers of studies validating their usefulness in certain situations.

Even now, research has shown that some herbals do seem to show modest benefit. I occasionally have recommended natural supplements to certain patients. Some of the more promising herbs are melatonin for sleep; St. John’s Wort for depression; red yeast rice for cholesterol; and black cohosh for menopausal symptoms.