Other Recommended Medicinal Herbs

Essential Oils (Geranium Oil) 

Background
Essential or volatile oils are aromatic oils extracted from plants. The pharmacopoeias of the late Middle Ages through the 19th century contained several essential oils, and they are still used in medicine today. Eucalyptus oils, camphors, and menthols are active ingredients in over-the-counter medicines; several volatile oils are used in dentistry as solvents and analgesics. These extracts are common ingredients in perfumes, toiletries, and soaps. They are also used as flavors. The chemistry of these oils and their principal components is relatively well understood, and many of the components have been synthesized.

Traditional Applications
Essential oils are volatile hydrocarbons produced by plants, which account for most of their characteristic smell; their function in nature is largely unknown. Their use by humans traces vaguely into antiquity, where the oils were contained in various unguents. Steam distillation provided the first practical source of the oils and came into widespread use in the 16th century, at which time pharmacies distilled their own oils. The alchemists’ retorts and reflux devices were often charged with herbs and spices, from which they gained returns of <0.5% of a volatile oil. The industry grew as the technology improved, with the main activity in the pharmacies and perfumeries.
     In the 19th century, the chemistry of the various component oils was the subject of extensive study, and assays for these components were developed for quality control. The high point of use and appreciation of essential oils appears to be the first half of the 20th century. Guenther published a definitive series of monographs (The Essential Oils, Vol 1-6, 1948-1952) that is still in print. Recently, aromatherapy has gained fashion, and there is a revival of interest in the naturally derived oils of various plants.

Pharmacology
The most common chemical structure of the essential plant oils is an unsaturated hydrocarbon of general form C10H16 , known as terpenes. Oxygen-containing compounds of the general formula C10H16O or C10H18O are the second most common class of constituents. The backbone of the terpenes can be divided into two isopentane chains C5H8, which are joined end-to-end in several configurations. Since the terpenes are six hydrogens short of saturation, they always contain a combination of double bonds and/or rings adding to three. Differentiation through isomerism, substitutions, ring-closures, and addition of functional groups gives rise to the thousands of individual components described to date. Moreover, many of these are convertible into each other, so some components are always present as mixtures. Enzymatic conversion has also been demonstrated, so the pharmacology in vivo is quite complicated.
     Biological activity of the essential oils has been studied for numerous types. Early uses included anti-helminthic activity of American wormseed oil, antibacterial activity of wintergreen, antitussive and analgesic activity for eucalyptus oil and menthol, and the many uses of camphor. Numerous over-the-counter remedies for colds, sores, halitosis, coughs, and sore throats still use plant-derived essential oils as active ingredients. For example, Listerine contains eucalyptol 0.091% w/v, thymol 0.063% w/v, and menthol 0.042% w/v. The coumarins are a type of essential oil and their use as thrombolytic agents dates from the early 20th century. Bergaptine is a photoactive compound used in tanning lotions. Pyrethin, the active ingredient in insecticides from chrysanthemums, is derived from a bicyclic terpene D3-carene by oxidation.
     Geraniol, the chief constituent of rose and geranium oil, is easily converted into the monocyclic alcohol a-terpineol, the chief constituent of the oil of hyacinth, and into linalool, which as acetate constitutes the characteristic component of lavender oil. Longer chains of terpenes give rise to many common compounds, such as the squalene, the carotenoids, such as b-carotene C40H56, and cholesterol.

Geranium Oil
Clinical studies have shown that using the essential oils of geranium and clove topically can temporarily decrease neuropathy pain. One research trial compared three strengths of geranium oil (100%, 50%, and 10%) with a mineral oil placebo and Zostrix, a capsaicin ointment. Subjects with post-herpetic neuralgia and moderate or greater pain were recruited. The patients completed pain assessments at times 0, 2, 5, 10, 15, 20, 30, 45, and 60 minutes following medication.

Results

•  Treatment with geranium oil produced a highly significant reduction in pain (p £ 0.002) compared to treatment with the placebo.
•  The reduction in pain produced by geranium oil appears to increase as its concentration increases (p £ 0.003). The observed increase is roughly linear, but a formal dose-response function cannot be defined because of the subjective nature of pain intensity.
•  These conclusions were true both for spontaneous pain and for evoked pain.
•  The response of an individual patient to treatment with geranium oil was similar for spontaneous pain and evoked pain (p £ .008): those who experienced relief with one kind of pain also experienced relief with the other.

Conclusions
The trial demonstrates that patients with neuralgia experience less spontaneous pain when treated with 100% and 50% geranium oil than when treated with a placebo, p £ 0.002. The averaged pain relief across all evaluated patients increased with increasing dosage of geranium oil, p £ 0.003. The same conclusions hold for the evoked pain (allodynia), p £ 0.0002.
    Approximately one third of the patients had major relief, with little or no pain remaining; another third had some relief, such as reduction from severe to moderate pain; and the remaining third did not experience any benefit from geranium oil. There were no significant adverse events from the use of geranium oil. Only four patients of 30 had any adverse reactions, all mild, which were either a transient rash that resolved within the hour, or a burning sensation in the eyes that resolved within minutes.
   Generally, users of geranium oil have reported that relief is experienced within
5 minutes and lasts for between 45 minutes and 6 hours, depending on the type and severity of the neuropathy.

Other Clinical Applications
Healthcare professionals have reported that geranium oil is useful for the following conditions in addition to diabetic peripheral neuropathies:

•  Shingles (Herpes zoster)
•  Post-herpetic neuralgia (PHN)
•  Reflex sympathetic dystrophies (RSD)
•  Spinal compression pain, including sciatica
•  Causalgias
•  Radiculopathies
•  Phantom limb pain
•  Fibromyalgia
•  Bell’s palsy
•  Trigeminal neuralgias
•  Myofacial pain

Evening Primrose Oil (Gamma-linolenic acid) 

Background
Evening primrose oil is obtained from the seeds of the evening primrose (Oenothera biennis). This oil is a rich source of omega-6 essential fatty acids, primarily gamma-linolenic acid (GLA) and linoleic acid, both essential components of myelin and the neuronal cell membranes. Commercial preparations of evening primrose oil are typically standardized to 2% to 16% GLA (8% typical) and 65% to 80% linoleic acid (72% typical), with vitamin E. GLA is formed by an enzymatic reaction involving the delta-6-desaturase enzyme. The enzymatic activity of delta-6-desaturase has been shown to be compromised in patients with Type I and Type II diabetes mellitus. This may make GLA less available to protect the nerve cells and also reduce production of prostaglandin series PGE1, which is anti-inflammatory.

Clinical Studies
Gamma-linolenic acid has shown promising results in the treatment of many types of diabetic complications in several human and animal studies. In one trial of diabetic neuropathy patients, which was double-blinded, 111 patients were given either 480 mg GLA or placebo daily. After 1 year, GLA-treated patients showed favorable improvement in subjective symptoms of peripheral neuropathy, such as pain and numbness, as well as objective signs of nerve injury. People with good blood sugar control improved the most.
      In another double-blind, placebo-controlled trial of 22 Type I and Type II diabetic patients with neuropathy, patients received 360 mg per day of GLA or placebo for 6 months. Patients receiving GLA had significant improvements in all six nerve function measurements and overall symptom scores. GLA, however, had no apparent effect on glucose control parameters. Side effects from GLA consumption were mild and similar for patients receiving evening primrose oil or placebo.

Dosage
In trials reporting positive results, a treatment duration of 6 to 12 months was generally required. The recommended dose of evening primrose oil, based on these studies, is nien to twelve 500-mg capsules each day, based on 40 mg of GLA per capsule. Equivalent GLA doses can be calculated using 1000 mg of EPO capsules or other oil capsules high in GLA, such as borage or blackcurrant oil capsules.

Safety and Side Effects
The side effect profile for evening primrose oil was generally mild and similar to placebo in the clinical trials mentioned.
20

Green Tea 

Background
    Much evidence is emerging that green tea has many promising health benefits. Green tea, especially green tea catechins (strong antioxidants found in green tea), have been shown to promote weight loss, prevent a wide variety of cancers, lower cholesterol, and promote a healthy digestive tract. Because green tea offers a wealth of other health advantages, including decreased risk of cancer, heart disease and lowers cholesterol, its consumption (or the supplementation with a green tea catechin extract) by diabetics or those seeking to prevent diabetes is indicated.

Clinical Studies 

Thermogenic Effect
Green tea has a thermogenic effect, which means that it supports the body’s ability to burn fat. A number of animal and human studies have confirmed the ability of green tea catechins to promote weight loss. In one Japanese study of healthy men, weight, BMI, waist circumference, body fat ratio, abdominal fat, total cholesterol, and fasting glucose were noted to have significantly decreased after 12 weeks of supplementation with 483 mg of green tea catechins per day. The body fat reducing effect of tea catechins was confirmed in a study of 82 healthy male adults. When green tea catechins were given as a tea-like beverage for 12 weeks at a dose of 690 mg per day, approximately 10% of abdominal fat was lost. Since this corresponds to approximately 6 to 8 cups of green tea per day, it is difficult for many people to ingest this level of green tea catechins without developing side effects of caffeine consumption. In this case, a standardized capsule of green tea catechins may be more convenient with fewer side effects.
     The value of catechins supplementation was confirmed by a study that isolated their effect on health. The study measured the 24-hour energy expenditure and fat oxidation of subjects who each consumed green tea extract, caffeine, or a placebo in three separate treatments. The researchers found that the green tea extract enhanced thermogenesis and fat oxidation that wasn’t explained solely by its caffeine content, concluding that the green tea catechins were responsible for the fat burning properties. They measured a remarkable 4% increase in energy expenditure of subjects over only a 24-hour period as a result of the green tea extract. This, in turn, has the potential to reduce body weight and influence body composition over the longer term.

Antioxidant Effect
Evidence to support the effect of green tea catechins as strong antioxidant compounds that may offer protection from diabetes or even play a role in its management is also seen in research on animals. One 12-week study undertaken at the National Taiwan University found that giving green tea to rats improved their insulin sensitivity and lowered their blood glucose concentrations. The rats also had an increased number of insulin receptors and a protein, GLUT-IV, which transports glucose molecules across cell membranes more efficiently.