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Naturalistic Fallacy – Plants are nature’s pharmacy

Posted by Don McLenaghen on June 16, 2011

Naturalist or those who practice herbalism often make the claim that nature is our pharmacy (a pitch line equally used by big Pharma); that natural remedies provided by plants are innately much better than those created by chemical laboratories.

This is a classic case of the naturalistic fallacy; that is if it is in or from nature it must be better.

First, I am not going to deny that there are a number of chemicals created by plants that have beneficial properties for medicine (aspirin for example). What I am addressing is the bifurcated claim that these remedies were in some way created FOR us and that they are somehow safer and better than man-made chemicals.

This issue was directly addressed earlier this year in a speech given by Dr Henry Oakeley, the garden fellow at London’s Royal College of Physicians at the opening in Dublin of the medicinal garden at Trinity College[1].

Dr. Oakeley at the opening of the medicinal gardens

Oakeley raised a few eyebrows when he stated that “PLANTS HAVE been trying to kill us, not cure us”. When asked why herbalism has persisted for over 3000 yrs. he responded that “Because they believed in the tooth fairy. They had no concept of illness or of chemistry or biochemistry. They believed all plants had been put on the earth by the creator for mankind’s use. So if the plant had a particular shape, it indicated that the creator had put it on the planet for a particular use.”

Now, I mentioned that current medical research uses the similar rhetoric…’nature is our pharmacy’. However the methodology is completely different. Medical research is based on modern scientific techniques and the scientific method. Herbalist believed that the powers-that-be, be they gods or sprites, left clues as to the ‘intended’ purpose of plants. An herbalist job is to decipher the code.


Sometimes herbalists get lucky; Ginseng[2] looked like a human figure and has been interpreted as a symbol of divine harmony on earth. It is used in ‘traditional medicine’ to improve sexual dysfunction, anti-agent, fight fatigue, boost the immune system and more[3]. It also has a number of compounds that medical research has shown actually does seem to help in reproduction[4] and other positive effects.

Sometimes it’s ridiculous, for example it was…sadly still is believed, that ground tiger penis in a soup[5] or tonic would increase a man’s virility. This of course is the best example of symbolic herbalism; tigers are strong and ‘virile’, therefor eating their ‘male essence’ will imbue that power to the consumer. This continued insanity has in no small way helped make Asian tigers an endangered species.


Sometimes it’s dangerous, for example, blue liverwort was once cultivated as a liver tonic because its three-lobed leaf mirrored the shape of the human liver. However, this tonic was in fact a toxin that produces jaundice[6]. More commonly seen “Aloe Vera Juice” can cause stomach cramps and is a suspected carcinogen[7].

Let us not forget either that cocaine, caffeine, hemlock, tobacco and pot are all natural herbs. However, most herbs are just medically inert and if they provide any benefit it is purely a placebo…an effect that can be the quite dangerous if it delays proper medical treatment.

Now to be fair herbalism is not completely limited to this sympathetic magic view. Over the years a certain degree of trial and error has ‘advanced’ herbalism beyond the simplistic symbolic notion of nature however until recently it has not been possible to extract, when present, the effective chemicals from the chemical stew that a plant may contain. I am not trying to imply that Chinese or native healers are inferior or that somehow westerners are smarter, no; what we have is a confluence of happenstance. Until the adoption of the scientific method, modern chemistry and technological advancements of the late 18th century, ‘western medicine’ was on the same methodological footing I am here criticising.

The scientific method allowed for a systematic reductionist view of the world allowing the identification of specific compounds/chemicals that are the true source of medicine; modern chemistry (and later biology and bio-chemistry) provided a framework for interpreting the results of experiments…showing links between cause and effects; and technology provided the tools to identify, purify and manipulate the compound with the aim of making them better.

Thus, if we continue with the pharmacy metaphor, modern medicines are like opening a bottle of aspirin and popping a pill to cure a headache. Herbal medicines are like pouring all your pills into a bucket, adding in your kitchen spices and maybe some random plants from outside; then taking a handful of this mix in the hopes you get the one pill that will reduce our headache.

Oakeley said “Herbalists say these things are pure and don’t have the same side effects as Prozac, [but] they have other side effects . . . That’s the problem with herbal medicine, there is no proper long-term check on the side effects. The thousands of years of plants being used as medicines have actually taught us very little. The basic concept that most people have missed is that [many] plants are poisonous. We just have to find a way of using the poisons in plants to our advantage”.

This I think lies at the heart of the naturalist fallacy for herbalism. It’s not that there are not useful chemicals to be found in nature but that these chemicals were ever intended to be medicinal. The term used is nature’s pharmacy, a more accurate description is a chemical armoury…a cornucopia of chemical weapons we extract as a kind of chemical waste product and re-task to a useful role for humanity. The chemicals we find in plants are there for a purpose, that is true, but for the plant’s ends not our own.

Plants create chemicals in an effort to provide for themselves an evolutionary advantage. Many times these efforts are aggressive; that is the plant benefits at the expense of its cohabitants…an example when a plant grows thorns it reduces the ability of herbivores to graze on them, what benefits the plant (less leaf loss) harms the grazer (less food). Many times these efforts are symbiotic…that is a benefit to the plant and its cohabitant…an example of this is the fig and fig wasp[8]. It’s also important to remember when plants do have these symbiotic relationships they are very species specific relationships; nectar is a common bribe for animals to pollinate plants but even this is very exclusive because the shape of the flower and the proboscis of the nectar eater are so extreme only one (or a limited set) animal can actual access the nectar. The plant does this to ensure that the bribed animal visits similar plants and thus increases the chances of successful pollination.

The chemicals we extract fall into three broad groups. First are those the plant produces to promote its own health…compounds that make the plant itself healthy and which coincidently we find useful as well; such as salicylic acid i.e. aspirin. If these compounds are useful to humans it is merely accidental/coincidental.

Second compounds created to make the plant more attractive to animals for the purpose of seed dispersal and rarely predation (ie Sundew plant); such as nectar, fruit and aromatics. These compounds are often useful to humans but their PURPOSE IS NOT FOR OUR WELL-BEING but merely a bride or scam to get animals to help the plant.

The last category, the one ironically we have found most useful, are those intended to attack…compound a plant used to fend off fungal infections (terpenes) or make itself unfit for animal consumption plant predators (capsicum i.e. pepper). These compounds are not only not intended to be beneficial they are created by the plant explicitly as a hostile act.  None of these were intended for humans nor are they specifically ‘safer’ for us than man-made chemicals. In fact the opposite is true.

Current research is done by extracting chemicals, testing their properties and interactions, attempting to tweak the chemistry to remove ‘side-effects’ and strengthen the desired property. Once this is done the resulting, naturally derived but whole-ly man-made, compound becomes a drug…no longer a herbal remedy (with dubious efficacy but medicine with empirical evidence of its effectiveness). Because we have a purer form of the active ingredient which has been stripped of the superfluous chemicals along with their potential side-effects; we can say that on a equal footing the man-mades are innately safer.

Last note, although I think scientific medical medicine is innately better than herbalism; I am not saying that ‘big pharma’ should be blindly trusted…they make errors as well. That is why I always and consistently support rigorous and thorough regulation and independent oversight of any industry (that would include the herbalist industry as well, as ineffective as i may think it…remember it is a MULTI-billion dollar a year industry[9])

Big Herbal Pharma...

[4]  Murphy and Lee Ginseng, sex behavior, and nitric oxide, Ann N Y Acad Sci. 2002 May;962:372-7 PMID

[6] IrishTimes

[7] Elvin-Lewis M., “Should we be concerned about herbal remedies”. Journal of Ethnopharmacology 75 (2001) 141-164.

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