False Tenets of Paraherbalism

Varro E. Tyler , Ph.D.

True herbalism encompasses scientific testing, honest reporting of the results, and safe use of effective herbs by informed practitioners and the public. It also includes the production and ethical marketing of herbal products. True herbalism, which brings honor to the wonder-filled world of plants, does exist as part of the science of pharmacognosy. However, there is a dark side to herbalism which I call paraherbalism.

Herbalism and paraherbalism can be compared to Dr. Jekyll and his evil self, Mr. Hyde. As with these famous fictional characters, danger is ever-present that the good of herbalism will be destroyed by the evils of paraherbalism. That would be tragic because herbalism can play a useful role in the health-care arena.

Paraherbalism is characterized by at least ten false tenets. While not every paraherbalist embraces all of them, enough do to conclude that all are characteristic of the field.

Tenet #1: A conspiracy by the medical establishment discourages the use of herbs.

One forceful statement of this tenet is Heinerman's assertion that, "A large percentage of this suspicion of herbs and natural healing methods is due to the unmitigated prejudice and slanderous opposition posed by the regular medical community at large. Quite often they are joined in this harmful conspiracy by the pharmaceutical industry." Others have suggested that herbalists (and other health food industry "pioneers") are automatically branded as quacks and charlatans by the "AMA-FDA combine."

I have never met a physician who knew enough about herbs to raise an opposing voice. Doctors who give herbal medicine any thought at all are rare. Physicians are taught nothing about the subject in medical school. If they become curious and purchase a popular book on the subject, reading that yucca roots are "mashed and boiled to make a tea for treating diabetes" might inspire them to file the volume among others devoted to superstition and witchcraft. They might even throw the book away, but they would not stop using insulin, which they know is an effective drug.

Inquisitive physicians might even look up the credentials of those whose writings on herbal remedies are most widely distributed. If so, they might find that Sybil Leek is described in Who's Who in America as an astrologer and wrote several books on witchcraft, including Diary of a Witch. They might also learn that Richard Passwater obtained his "Ph.D." from an unaccredited correspondence school that was not authorized to grant degrees. Such credentials are not likely to inspire scientifically trained physicians to have much confidence in the paraherbal advocates.

In the pharmaceutical industry, another attitude prevails. Here it is recognized that plants have yielded effective drugs like opium, digitalis, ergot, belladonna and rauwolfia. But there is insufficient profit potential to stimulate much research into new plant drugs. With the cost of developing a new chemical entity into a marketable drug now over $100 million, pharmaceutical manufacturers focus on products where patent protection can be achieved rather than widely used plant remedies that probably cannot become patentable drugs. Again, there is no conspiracy but simply a lack of expected profit.

Tenet #2: Herbs cannot harm, only cure.

It is ancient dogma--repeated in modern herbals--that drugs of vegetable origin are automatically good, but those derived from minerals or petroleum are necessarily bad. William Smith, for example, states in Wonders in Weeds that: "It cannot be emphasized too highly that herbal medicine is 'safe medicine,' a claim that cannot be applied to orthodox remedies."

This thesis denies the fact that some plant constituents are among the most toxic substances known. Acutely toxic alkaloids, ranging alphabetically from aconitine to zygadenine, are abundant. Other constituents, such as the peptide amatoxins in certain fungi, can also kill. Even so, consumers are probably less likely to suffer from acute strychnine poisoning by eating Nux vomica seeds than they are to receive exposure to milder and less obvious toxins through repeated use of such remedies as sassafras or comfrey. And certain diterpine esters are co-carcinogens (tumor promoters).

Tenet #3: Whole herbs are more effective than their isolated active constituents.

Many modern paraherbalists maintain that plants are not only the safest way to administer medicine, but also the most effective. They claim that apart from their active principle, plants may contain other substances that enhance their therapeutic action by some sort of a synergistic process.

Perhaps the most persistent advocate of this doctrine has been Andrew T. Weil, M.D., who argues, "In the case of drug plants, the whole forms, being complex mixtures and therefore impure, tend to be safer than their unmixed derivatives, freed from diluents and made available in highly refined form." Weil also argues that the lesser concentration of an active constituent present in plant tissue renders such a drug safer to use. Finally, he contends that the various active constituents in a plant work synergistically to produce a total effect greater than the mere sum of the individual component activities.

Weil's first two points can be dismissed simply by pointing out that dosage, which governs a drug's safety and efficacy, is much more readily controlled with purified constituents. Synergism occasionally occurs, but for every case where a desirable action is enhanced, there are several where undesirable actions are produced. For example, cinchona bark contains some 25 closely related alkaloids, but the only one recognized as useful in the treatment of malaria is quinine. A person who took powdered cinchona bark would also ingest the alkaloid quinidine, a cardiac depressant, and cinchotannic acid, which would induce constipation.

An even more significant example is comfrey, whose leaves and underground parts are widely recommended by modern herbalists as wound-healers. Whatever activity of this sort the plant possesses is due to its content of allantoin, an agent that apparently promotes cell proliferation. However, comfrey also contains carcinogenic pyrrolizidine alkaloids, including echimidine and symphytine. Purified allantoin, free from accompanying carcinogens, would obviously be safer to use.

Tenet #4: "Natural" and "organic" herbs are superior to synthetic drugs.

Paraherbalists claim that products made by the metabolic processes of plants or animals possess an innate superiority over identical products synthesized in a chemical laboratory. The falsity of this claim was demonstrated as far back as 1828 when the German chemist Friedrich Wohler synthesized urea from inorganic materials. Wohler's synthetic urea was identical in every respect with the urea biosynthesized and excreted by animals or biosynthesized and accumulated by many species of higher fungi. Thus, statements like, "The pharmaceutical industry needs to stop fooling around with dangerous synthetic chemicals and return, once again, to the more natural substances God has placed upon this earth for our health and benefit," are derived from baseless belief rather than scientific methodology.

The term "organic" is used to describe plants grown without pesticides or synthetic fertilizers. Materials made from such plants are believed to be superior in some way to those produced by conventional agriculture. This belief is based on a complete misunderstanding of plant nutrition and physiology. Plants require inorganic nutrients such as nitrogen, phosphorus and potassium for normal growth. They obtain these elements from the soil and have no mechanism for distinguishing their original source. If adequate amounts are present, plants grow normally. If they are not, this does not occur.

Pesticides are a slightly different matter. Appropriate safety limits have been established, and some pesticides have been banned. It is possible to grow plants without using pesticides, but yields per acre are much diminished. So one either trusts scientific farmers and the regulatory process or one pays considerably more for food.

Tenet #5: The "Doctrine of Signatures" is meaningful.

The three most popular aphrodisiacs sold in the Orient owe their alleged properties to the so-called Doctrine of Signatures--the ancient belief that the form and shape of a drug source determine its therapeutic virtue. Thus, rhinoceros horn, deer antlers, and ginseng root with their phallic resemblance (or in the case of bifurcated ginseng with attached rootlets, its similarity to the human body complete with phallus) are all highly esteemed as agents of virility. In Chinese pharmacies, antlers are typically displayed on velvet mats in glass showcases and sold at prices comparable to fine pearls.

Deer antler and rhinoceros horn have never been proven to contain any constituent that stimulates libido or cures impotence. Any activity should be attributed to placebo effect. Ginseng does contain triterpenoid saponins, to which various physiological activities have been attributed. However, no substantial evidence that ginseng enhances sexual experience or potency has been published in the scientific literature.

The Doctrine of Signatures is not unique to the Orient. Gerard reported in 1597 that eyebright juice applied to the eyes, "taketh awaie the darknesse and dimnesse of the eies and cleereth the sight." Variations of this advice are duly repeated by most present-day paraherbalists.

Actually, no constituent of eyebright is known to be effective against any eye disease. Medieval herbalists assumed it was effective because the white to bluish corolla of its flower bears a bright yellow spot, making it resemble an eye with its pupil. Believing that this structure makes the plant effective against eye disease makes as much sense as believing that walnuts are good for mental illness because their kernels resemble the brain or that liverworts are good for jaundice because their leaves resemble the shape of the liver.

Tenet #6: Reducing the dose of a medicine increases its therapeutic potency.

This, like the Doctrine of Signatures, is a principle espoused by homeopaths. Founded near the end of the 18th century by Samuel Hahnemann, a German physician, homeopathy originally had three basic tenets: 1) diseases are cured by small doses of drugs which, when administered in large doses to healthy persons, produce effects similar to the symptoms of the disease; 2) the potency of a drug is inversely proportional to its concentration; and 3) chronic diseases are simply manifestations of a suppressed itch or psora, a kind of evil spirit. This last notion proved so outrageous, even to fervent homeopathic practitioners, that it was soon abandoned.

The eighth (1980) edition of the Homeopathic Pharmacopoeia contains some 600 pages of monographs, most of them on drugs of plant origin. Homeopathic remedies in this book are recognized as drugs under federal laws, a fact appreciated by paraherbalists. Some of the listed substances, such as cinchona, digitalis and opium, are effective in appropriate dosage. But homeopathy advocates high dilution for maximal effect. Many homeopathic remedies are so dilute that they are statistically unlikely to contain a single molecule of the original substance.

Still, there has been a resurgence of interest in homeopathy in this country in recent years. Its supposed safety and "holistic" orientation, coupled with its vast materia medica of vegetable drugs, appeal to many paraherbalists.

Tenet #7: Astrological influences are significant.

In his recent book, Herbs, Health and Astrology, Leon Petulengro comments, "Knowing as we do that planets and stars emit their own individual signals or vibrations, how can we disbelieve that ancient lore was right and that herbs and plants, and indeed humans, are ruled by these various vibrations or force fields?"

How, indeed? Just compare drugs with similar physiological effects and the different planets to which they are assigned. For example, broom, digitalis, lily-of-the-valley and black hellebore all yield drugs that can slow the heartbeat, render it more regular, or otherwise strengthen it. But they look quite different from one another and belong to different plant families. Probably for this reason, the leading 17th-century astrologer and apothecary, Nicholas Culpeper assigned each to a different "governing" planet-- a classification repeated by Sybil Leek.

Culpeper assumed that diseases caused by a certain planet are cured by herbs of the same planet or the "opposite" planet. For example, since diseases of the heart and blood vessels are caused by the sun, they should be cured by herbs dominated by the sun or ruled by Saturn. If this were true, black hellebore would be the only herb in either of the above categories that is effective against heart disease. Actually, it is probably the least effective cardiotonic drug considered by Culpeper and was dropped from the United States Pharmacopoeia in 1882. Broom was officially listed until 1936 (and its active principle until 1950), and lily-of- the-valley root appeared until 1950. Digitalis is still listed together with its constituent glycosides, which are extensively used. Thus, astrological reasoning classified only one out of four correctly and selected the worst example.

Looking in reverse, let's assume, as Culpeper would have us do, that herbs "dominated" by the sun do indeed strengthen the heart by sympathy. Saffron, he says, "is an herb of the Sun, and under the Lion, and therefore you need not demand a reason why it strengthens the heart so exceedingly." Juniper, he writes, "is an admirable solar shrub." Lovage, he continues, "is an herb of the Sun." Of rosemary, he notes, "The Sun claims privilege in it." None of these plants has any significant cardiac effect. In fact, of the more than thirty plants described by Culpeper and Leek as herbs of the sun, only mistletoe--which is fairly toxic--has any appreciable effect on the cardiovascular system.

Tenet #8: Physiological tests in animals are not applicable to human beings.

When it suits their purposes, paraherbalists typically complain that the results of animal experiments should not be applied to herbs. Heinerman has said, for example, that sassafras was removed from the marketplace "because a bunch of 'puny, sickly, all-around crummy rats' just happened to get cancer when this plant was injected into them by their larger, less intelligent relatives."

It is true that great differences exist among various animal species and between animals and humans. However, there is a high probability of significance when diverse species show similar effects. For this reason, new drugs should be evaluated in several animal species, preferably from different orders. Herbs do need to be tested for safety and effectiveness. If animal testing is not acceptable to paraherbalists, the only alternative--initial screening of drugs in human-- is even less acceptable to the public.

Tenet #9: Anecdotal evidence is highly significant.

A century ago, glowing testimonials were widely used to sell patent medicines. Today, similar ones are used for herbal remedies. For example, Herbal Success Stories, published in 1980, recounts "actual case histories" of those who "either experienced the problem and cure themselves or helped a family member or friend with the ailment or cure." According to the author, readers can "use this book with assurance that successes related there are true."

Unfortunately, in individual cases, it is difficult or impossible to tell whether a reported cure resulted from the treatment, a placebo effect, or the body's ability to heal itself. It may also be difficult to tell whether an anecdote has been reported accurately or was even fabricated. Anecdotal evidence can provide leads for research, but it is not reliable for establishing therapeutic utility of an herb. That requires preliminary investigations in laboratory animals followed by randomized, double-blind clinical trials in humans.

Tenet #10: Herbs were created by God specifically to cure disease.

Many paraherbalists claim that God has provided a remedy for every disease that might afflict us. This claim may appeal to deeply religious people, but is not testable and is not a legitimate substitute for scientific evidence.


Dr. Tyler, who died in 2001, was the Lilly distinguished professor of pharmacognosy (the science of medicines from natural sources) at Purdue University. A world-renowned authority, he wrote The Honest Herbal, an evaluation of popular herbs, and was senior author of the textbook Pharmacognosy. This article was adapted from the November/December 1989 issue of Nutrition Forum Newsletter.

This article was posted on August 31, 1999.