Why medicinal herbs must be grown organically


After many years researching herbal medicines, and what improves their efface in treating illness, I have come to the conclusion that it is essential to use organically grown plants if one is going to use herbs as medicine. Herbal medicine is big business world wide now and with big business comes big corporations mass producing product, using raw materials that are grown using fungicide and pesticide chemicals and after harvesting them are manufactured them inappropriately. The resulting product will have little medicinal value.

The basic truths of herbal medicine have been known since antiquity but, recently, reductionist analysis has helped explain much of it in modern terms. We now know that key phytochemicals essential to a plant in order for it to become a good herbal medicine in most cases is based on its content of Secondary Metabolites. Secondary metabolites are organic compounds that are not directly involved in the normal growth, development or reproduction of plants. Unlike primary metabolites, absence of secondary metabolities results not in immediate death, but in long-term impairment of the organism's survivability/fecundity(1).

Secondary Metabolites

The immobility of plants in diverse and changing physical environments, along with the possibility of attack from animals and pathogens, has necessitated the development of numerous chemical mechanisms for protection and offence. These chemical mechanisim are its secondary metabolites. Under most conditions, plants produce several thousands of these compounds, and invest huge amounts of their metabolic energy, sometimes up to 90% of their nitrogen resource, into producing them.

Secondary Metabolites are usually produced in response to even low level competition. In the semi-sterile cultivations favoured by non-organic chemical methods of farming, plants have no effective competition and so no need to produce these compounds. In the total absence of natural competition, selection pressures favour the production of plant mass either devoid of, or with reduced proportions of these metabolically expensive compounds. One consequence of this is that even though they may give an impression of quality, the appearance and color of an herb are not necessarily indicators of its therapeutic quality. Indeed, plants grown under adverse conditions may sometimes have a poor appearance but higher levels of secondary metabolites.

In recent years considerable attention has been paid to the specific ecological roles of secondary metabolites, which were often formerly regarded as waste products (2).

Alkaloids

Alkaloids are thought to play a defensive role in plants against herbivores and pathogens(3). The alkaloids are said to be the active constituent responsible for the stomachic(has a medicinal action on the stomach) action of the herb Wild Yam (Dioscorea spp.)(4). Atropine is an alkaloid and main active constituent of Deadly nightshade (Atropa belladonna). Alkaloids are central to the effece of other medicinal herbs such as Damiana (Turnera diffusa) and Celery seed (Apium graveolens)

Glucosinolates

Glucosinolates play a role in protecting the plant against insect attack(5). Black Mustard contains the compound ‘sinigrin’ and White Mustard contains ‘sinalbin’, both of which are metabolised to glucosinolates. These glucosinolates are thought to be key to the rubafacient action of the herb.

Tannins

Tannins act to preserve the wood in living trees from microbial decomposition and insects(6). Tannins are key constituents of the following medicinal herbs Black cohosh (Cimicifuga racemosa), Green tea (Camellia sinensis), St john's wort (Hypericum perforatum) and Meadowsweet (Filipendula ulmaria).

Several classes of secondary metabolites are induced by infection, wounding or grazing. Variation in the speed and extent of such induction may account at least in part for the differences between resistant and susceptible varieties(7). Both salicylic and jasmonic acids have been implicated as signals in such responses. Toxic chemicals formed in response to damage, especially from fungal attack, are called phytoalexins(6). In legumes, secondary metabolites are involved in interactions with beneficial microorganisms (flavonoids as inducers of Rhizobium symbiosis) and in defence against pathogens (isoflavoniond phytoalexins)(8)

Plants have also developed defence against other plants, a phenomenon known as ‘allelopathy’. Many compounds are implicated, including phenolics(9) and terpenoids(10), again both key active constituents in medicinal herbs.

Positive interaction, or facilitation, among plants is also becoming increasingly recognized(11). UK based company Natures Defence are currently researching this phenomenon. Chief research Anthony Daniels recently told me that a current focus of research is on a gaseous defence mechanism that exists in plants. “If a plant is being attacked by pest or fungus it secrets a certain gas that initiates the production of secondary metabolites in neighbouring plants exposed to the gas”. This is amazing as it shows that there is a very intelligent communication mechanism between plants that result in the production of more (protective) medicinal constituents within the plants, when there is a pest or fungus in the area.

Research on Secondary Metabolites is in its infancy, but so far it has indicated very strongly that if one is going to use herbs medicinally then they should be either grown organically or wild crafted to maximise the potential of the plant as a medicine. This can also be extrapolated to all other members of the plant kingdom too, specifically your fruits and vegetables.

In Health

Gabriel



Reference

(1) Gibson, Shawn. University of Saskatchewan, Pl Sci 416, 2002
(2) Mills and Bone, Principles and Practice of Phototherapy; Modern herbal medicine, Edinburgh, 2000, Churchill Livingstone
(3) Castells E, Penuelas J. Towards a global theory of chemical defence: the case of alkaloids(French). Orsis 1997; 12:141-161
(4) Bruneton, J, 1995, Pharmacology, Phytochemistry, Medicinal Plants, Lavoisier, Paris, France, p 546
(5) Oleszek W. Glucosinolates: occurrence and ecological significance. Wiadomosci Botaniczne 1995; 39(1-2):49-58
(6) Laks PE. Wood preservation as trees do it. Scottish Forestry 1991; 45(4): 275-284
(7) Bennett RN. Tansley review no. 72
(8) Dixon RA. Metabolic engineering: prospects for crop improvement through the genetic manipulation of phenylpropanoid biosynthesis and defence response: a review. Gene 1996;179(1):61-71
(9) Inderijt. Plant phenolics in allelopathy. Botanical Review 1996; 62(2):186-202
(10) Langenheim HJ. Higher plant terpinoild: a phytocentric overview of their ecological roles. Journal of Chemical Ecology 1994;20(6) : 1223-1280
(11) Callaway R. Positive interactions among plants. Botanical Review 1995;61(4): 306-349

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