If there’s one thing I’ve been consistent about, it’s that, however ridiculous all the other woo I routinely discuss here is—homeopathy, reiki, reflexology, I’m talking to you and your friends—herbal medicine and supplements might have value because they might have a physiological effect that is beneficial in treating or preventing disease. Of course, if that’s the case, it’s because the herb or supplement contains chemicals that act as drugs. They’re “dirty” drugs in that they are mixed with all sorts of other substances in the herb or supplement that might or might not have effects, which means that different lots of the herbs or supplements often have different activity, but they are drugs nonetheless. That’s why, for instance, doctors don’t tell patients to chew on foxglove leaves when they want a patient to get digoxin. Digoxin is a powerful drug with a relatively narrow “therapeutic window,” meaning that the difference between the levels of the drug in the blood needed for therapeutic effect are not very far from toxic levels; so predictable, reliable drug content is essential. I just learned a while ago that within the living memory of some older physicians digoxin actually was prescribed as crude extracts, which was very difficult and dangerous, hence the necessity of purification. In other cases, (such as Artemisinin, for which Youyou Tu was recently awarded the Nobel Prize in Physiology or Medicine), crude plant extracts do not contain sufficient quantities of the active component, necessitating its isolation, purification, and, in some cases, chemical modification to increase its absorption, stability, or activity.
One thing that proponents of herbal medicine and supplements often forget, though, is that if herbs or supplements can have potentially beneficial effects (albeit difficult to regulate effects due to the crude, impure nature of the extracts often used) because they contain drugs, then herbs and supplements can also produce adverse events, again, because they contain drugs. You can overdose on herbs and supplements. This point was recently reinforced by a new study by Geller et al. published last week in the New England Journal of Medicine (NEJM), entitled “Emergency Department Visits for Adverse Events Related to Dietary Supplements.” It was carried out by investigators from the Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, and Chenega Government Consulting; and the Center for Food Safety and Applied Nutrition and the Division of Public Health Informatics and Analytics and the Division of Dietary Supplement Programs, Food and Drug Administration. The title pretty much tells you what the study is about, and what the study is about is that dietary supplements cause a lot of visits to the emergency room every year; 23,005 (95% confidence interval [CI], 18,611 to 27,398) emergency department visits per year can be attributed to adverse events related to dietary supplements.