Aug 10 2009
Black Cohosh is a common herbal or botanical treatment for the hot flashes and other symptoms of menopause. This treatment appeals to women who want a more natural or gentle approach to their symptoms. Unfortunately, as the latest research shows, it doesn’t work.
Interest in herbal medicine has increased in the last 15 years as a response to weakened regulation and a successful marketing strategy by the supplement industry in the context of a cultural phenomenon of changing attitudes toward medicine. This has mainly led to, however, confusion about what herbal therapy really is. Most people I talk to think of herbal treatments as natural supplements – but they are not supplements and being “natural” is irrelevant. In fact it is much more accurate to think of them as unpurified drugs.
Botanical research is a legitimate and useful branch of pharmacology, with its own experts. The plant kingdom is a vast chemistry laboratory, specializing in chemicals that have some effect on other living things. The process of experimentation through evolution is slow, but has had hundreds of millions of years to operate. As a result we are surrounded by plant-based chemicals – some benign, most toxic, and a few with pharmacological properties we can exploit to our advantage if we’re careful.
That these chemicals are “natural” is meaningless. Beyond the fact that the term in this context has no useful operational definition, that these chemicals exist in nature should give us no comfort. They exist for the survival of the plant, mostly at the expense of animals who might want to eat it. No plant evolved to be a useful medicinal for one egocentric mammalian species. Toxicity, however, is all about dose, and in essence all useful drugs are simply toxins with a dose range in which they have an effect that can be exploited with acceptable side effects.
Also, plants have dozens or hundreds of chemicals in them, and these vary in different parts of the plant, in different times of the season, in different regions, and from year to year. They are very dirty drugs, with variable doses of potentially useful but also strictly harmful substances. Botanical pharmacology focuses on identifying useful plants, and then figuring out which chemical substances in them are useful and which are simply adding toxicity. Useful chemicals can then be purified, quantified, and studied for their biochemistry and net health effects.
I still have a hard time understanding why someone would want to treat themselves with a dirty herb containing highly variable doses of multiple chemicals, rather than a precisely known quantity of a specific chemical with known properties. The justification I am almost always given is because they are “natural” – but as I pointed out, this is no justification at all, but clever marketing bordering on mythology.
The one saving grace of herbs is that the doses of most chemicals within them is likely to be low and therefore below the level of toxicity – or any useful effect, either. This does not mean their safety can be assumed, and many herbal remedies have been found to have toxicity, (like kava kava and liver toxicity or kidney failure from a variety of botanicals) or to interfere with prescription drugs (so-called drug-drug interactions – because they’re drugs).
Once modern pharmacology came into its own our accumulated wealth of botanical knowledge was raided for useful drugs, and they now comprise the majority of the drugs we use today. We have already plucked the low hanging fruit. There are likely to still be useful drugs out there in the plant kingdom, but it will take some investigation and research to find them. Such efforts are ongoing, and will likely continue to feed pharmacy shelves for years to come.
However, the herbal remedies that have come into popular use are generally not the result of investigation and careful research, but either tradition (read anecdotes) or modern marketing masquerading as tradition. For example, echinacea may have been used by Native Americans for many things (as was tobbaco, incidentally) but they did not use it for the common cold. That use was an invention of a German herbalist who used the Native American angle for marketing purposes.
It is therefore not surprise that the herbs most commonly marketed today for common ailments (read large customer base) have mostly failed in clinical trials. Gingko does not work for memory or mental focus, echinacea does not treat the common cold or its symptoms, and St. John’s Wort has minimal to no effect on depression. Black cohosh for menopausal symptoms was held up as an herbal remedy that actually works, but now we have evidence from a double-blind trial that is clearly negative.
This trial had four arms – including black cohosh, red clover, placebo, and standard hormonal therapy. They followed women with menopausal symptoms for 12 months and found that, over time, they all had a decrease in symptoms by 34, 57, 63 and 94 percent respectively. The black cohosh and red clover were not statistically significantly different from placebo, while the hormonal therapy was significantly improved from placebo. The primary weakness of the study, which was generally well designed, was that it enrolled only 89 women – this is enough to run meaningful statistics, but is smallish for a clinical study of this type.
The study also examined memory in the subjects and found no difference again among black cohosh, red clover, and placebo and a slight negative effect from hormonal therapy. So – standard hormonal therapy works, with a slight side effect on memory. The botanicals black cohosh and red clover had no detectable effects or side effects – not surprising. No one study is ever the final word on questions of clinical safety and efficacy – but the trend for research into popularly marketed herbs is definitely negative.
This, of course, raises many questions about regulation and research. The current regulation in the US is abysmal – botanical drugs are treated as if they were vitamins, and companies can even make pseudo-health claims for them (so-called structure-function claims), while having no obligation to prove safety. Research is now often funded by the NCCAM, which recently came under criticism for spending 2.5 billion dollars of tax payer money over the last decade and having nothing to show for it. This might have something to do with using politics to create a center specifically to bypass the usual methods of deciding what is useful to research.
As I said – botanical research is already a separate and useful branch of pharmacology that can be funded through other centers at the NIH. In fact this legitimate research is marginalized when brought under the umbrella of “alternative medicine” – another marketing term with no useful definition.
The good news is that quality clinical research into the effectiveness and safety of commonly used herbal remedies is being done. This research recently has largely been negative, which is not surprising given the history and nature of many of the products being studied. The bad news is that common use, regulation, and marketing are almost completely divorced from the scientific research. What, then, one might wonder, is the purpose of the research?
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