Looking for “natural cures”

Although this may be more up Abel Pharmboy‘s alley than mine, there was an article in the New York Times yesterday that indirectly demolished one of the favorite claims of advocates of “natural” medicines and cures. Appropriately enough, it appeared in the Business section. It also demonstrated just what a big business finding natural compounds with therapeutic properties.

The story opens with a description of Chris Kilham, ethnobotanist, a man who’s searched the world for medicinal plants:

Part David Attenborough, part Indiana Jones, Mr. Kilham, an ethnobotanist from Massachusetts who calls himself the Medicine Hunter, has scoured remote jungles and highlands for three decades for plants, oils and extracts that can heal. He has eaten bees and scorpions in China, fired blow guns with Amazonian natives, and learned traditional war dances from Pacific Islanders.

But behind the colorful tales lies the prospect of money, lots of money — for Western pharmaceutical companies, impoverished indigenous tribes and Mr. Kilham.

Let’s not forget this. Natural products to be used for supplements and medicines have become big business, and big pharma has has seen the potential for easy profits, mainly because “supplements” do not have to be subjected to clinical trials, as long as the health claims made for them are sufficiently vague:

Products that once seemed exotic, like ginseng, ginkgo biloba or aloe vera, now roll off the tongues of Westerners. All told, natural plant substances generate more than $75 billion in sales each year for the pharmaceutical industry, $20 billion in herbal supplement sales, and around $3 billion in cosmetics sales, according to a study by the European Commission.

Although the efficacy of some of the products the herbal ingredients go into is hotly debated, their popularity is not in doubt. Thirty-six percent of adults in the United States use some form of what experts call complementary and alternative medicine, CAM for short, according to a 2004 study published by the National Center for Complementary and Alternative Medicine, a division of the National Institutes of Health.

Yes, there’s little doubt that herbal remedies are popular, but just because they are popular does not mean that they are efficacious. Because they are popular, however, does mean that the production of various herbal supplements can be very lucrative indeed, a fact of which big pharma has taken note. Of course, there’s also no doubt that substances derived from plants have resulted in some of the mainstays of pharmaceutical treatments. Examples are numerous, including the anticancer drug Taxol (derived from the bark of the Pacific Yew tree), aspirin (willow bark), digoxin (foxglove), the anticancer drug vincristine (Madagascar periwinkle), morphine (the poppy plant), among others. True, pharmaceutical companies generally isolate the active compound from the plant and then usually develop a means of synthesizing it, mainly because it can be problematic to provide sufficient supplies of drug from natural sources, as was the case for Taxol. Early on in the history of Taxol, it was feared that it would not be possible to produce enough drug from the bark of the yew tree alone. In other words, ecological concerns alone can make it desirable to make synthetic versions of these drugs. After all, would we want to decimate the population of endangered plants just to supply these drugs? Moreover, the modifications to these chemicals are often undertaken to increase their activity or make them more readily absorbed by the gastrointestinal tract.

Unfortunately, as this article makes clear, there is the mistaken belief that just because a drug is “natural” or derived from a plant it must be safer, a belief that Kilham promotes in this article:

Mr. Kilham believes multinational drug companies underutilize the medicinal properties in plants. They pack pills with artificial compounds and sell them at huge markups, he says. He wants Westerners to use the pure plant medicines that indigenous peoples have used for thousands of years.

“People in the U.S. are more cranked up on pharmaceutical drugs than any other culture in the world today,” Mr. Kilham said. “I want people using safer medicine. And that means plant medicine.”

What a load of tripe! This is nothing more than two fallacies. First is the appeal to ancient knowledge. Many indigenous peoples also believe in spirit worship or that praying can bring rain. Does that mean that spirits in fact exist or that praying will bring rain? After all, it’s “ancient knowledge.” Just because a practice is supported by tradition and hundreds of years of use doesn’t necessarily make it superior to more recent developments. In fact, it doesn’t even imply that it’s effective at all. One only has to point to the persistence of homeopathy or Ayurvedic medicine to drive this lesson home. This is particularly true in the case of drugs, where confirmation bias and regression to the mean can provide the appearance of effectiveness even when none exists above that of placebo. Indeed, it was because of the recognized shortcomings of anecdotal evidence and personal experience in determining whether treatments were efficacious or not that medical scientists developed randomized, placebo-controlled clinical trials, which, after all, are a recent innovation in the scope of medical history. Plant-derived treatments discovered by indigenous peoples may be effective. Or they may not. If no data exists they have to be subjected to the same tests that any pharmaceutical company-produced drug does. Just because they are believed to be effective does not mean that they actually are. Worse, he’s promoting the erroneous view that just because a drug is “natural” or “plant-derived” it must be safer. As I like to say, I have news for people who make these claims: Curare is all-natural, too, and cyanide is found in peach pits. Indigenous peoples seem to know what advocates of alternative medicine forget: that nature can produce some of the most deadly toxins known to humans.

Kilham demonstrates even more flawed thinking:

In Peru, Mr. Kilham is betting on maca, a small root vegetable that grows here in the central highlands — “a turnip that packs a punch,” he says, adding “it imparts energy, sex drive and stamina like nothing else.”

That view is supported by studies carried out at the International Potato Center, a Lima-based research center that is internationally financed and staffed. Studies there show maca improves stamina, reduces the risk of prostate cancer and increases the motility, volume and quality of sperm.

Some peer reviewed studies published in the journal Reproductive Biology and Endocrinology backed up those findings.

And:

Today, Chakarunas organizes local growers to sell their maca to the French firm Naturex, which extracts it into concentrate. Naturex sells the concentrate to Enzymatic Therapy, a Wisconsin-based company that makes and markets the finished maca products.

I decided to see if I could find this peer-reviewed literature. After all, claims that a supplement “imparts energy, sex drive, and stamina” sounds more like a sales pitch on a late night infomercial than a finding in peer-reviewed scientific literature. There have been studies suggesting that maca extract can increase sperm count in rodents1, 2, 3, 4, possibly reduce prostatic hyperplasia1, 2, 3, and that it might have positive effects on depression and cognition1, 2. However, like any other drug, maca extracts may have side effects, as well, including a modest increase in diastolic blood pressure and liver function tests.

I couldn’t find any indications that maca extract imparts “energy” or “sex drive,” at least not in humans, given that all the studies I could find looking at these questions were done using rats or mice. Of course, few people will actually go and look at the peer-reviewed literature when someone like Kilham makes claims that sound more like a woo-meister than a scientist in assessing the potential pharmaceutical activities of various maca extracts. Consequently, people reading the NYT article may conclude that there is actually evidence to support his claims. There isn’t, or at best it’s spotty and based on animal studies. Indeed, the effects seen in rodent models were relatively modest, and it is not at all clear if they will translate into humans under controlled clinical trials with objective measurements.

What this article reminds me, at least, if no one else, is that the entire division of therapeutic drugs into “natural” drugs or “synthetic” or “pharmaceutical” drugs is wholly a false dichotomy. A drug is nothing more than a substance that has a reproducible physiological effect in the human body other than nutrition that can be used for therapeutic or harmful purposes. The body doesn’t give a rodent’s posterior whether the compound being used as a drug is derived from a plant, the end result of a complex chemical synthesis cooked up by the Dark Lords of Big Pharma themselves in order to bilk unsuspecting millions of huge sums of money for a “me-too” drug, or pulled out of someone’s butt. It can’t tell the difference. The drug will work by binding to a receptor or modulating some other physiological process on a purely physical, chemical basis. The true dichotomy is between pure drugs, whether derived from plants, chemically modified from a plant product, or de novo chemical synthesis that work reproducibly or impure plant extracts that may have hundreds of contaminants whose activity can vary from batch to batch. Does this mean that “natural” products and supplements are not useful or therapeutic? Of course not. Although rare, synergy between various components of an herbal concoction is a possibility. However, what all too many advocates of “natural” cures seem to want is that their favorite herbs and supplements be exempt from the same necessary scientific experiments and clinical studies to which pharmaceuticals are normally subject. However, if advocates are going to make claims of pharmaceutical activity for these supplements and herbal remedies by claiming that they are useful to treat disease, then these compounds should be subject to the same standards that any other drug would have to meet.