Herbal helpers
Welcome to the herbal helpers page! My plan is to slowly but surely build a database of some of my favourite herbs that I often find myself using time and time again in clinical practice. Click on the name of the herb to read the info. I hope you find it useful!
Ginkgo biloba |
This beautiful tree has been in existence for over 200 million years, thus being the oldest species of tree on the planet. It is so hardwearing, that a large specimen standing in the grounds of Hiroshima castle withstood the blast from the atomic bomb, when the castle crumbled! I have stood next to this very tree and the only evidence of any damage is the lower section is completely bald - no bark has grown there since the bomb.
Ginkgo biloba is now probably one of the most famous herbal remedies worldwide, and along with St John’s wort, the most widely prescribed natural remedy of conventional medics. It is famed for its ability to support and improve the health of the circulatory system, and enhance cognitive function (a consequence of the former). It has recieved vast amounts of attention in the mass media, particularly in the western world, and is amongst the top 3 selling herbal products in health food stores. But what exactly is this plant doing to instigate these wonderful effects, and how can it influence various health complaints and disease states?
Actions
One of the most widely researched and clearly understood actions of Ginkgo is its ability to improve circulation to the peripheral organs including fingers, toes, and most frequently documented - the brain. This herb has been shown to relax blood vessels that are in spasm or overly contracted, and dilate those that are abnormally constricted (Boon & Smith 2003:142). Many studies have revealed that Ginkgo seems at its most active at sites of ischemia (2003:142). The relaxant effect that it produces is thought to be due in part to the flavonoids present prolonging the half-life of ‘endothelium-derived relaxing factor’ (2003:142). There are also possible interactions with cyclic-GMP phosphodiesterase, prostaglandins, and nitric oxide (NO) (Barnes et al 2002:250).
Another very interesting action of this herb is an antagonistic action against Platelet Activating Factor (PAF). This gives it the ability to greatly reduce PAF induced thrombus formation. This is why this plant is so commonly taken as a prophylactic agent in the prevention of heart attacks and strokes. However, this does raise some safety issues. This herb must not be used by patients taking warfarin and heparin. If this is not followed, patients may be at serious risk of haemorrhage.
Clinical Applications
Intermittent Claudication - This condition is characterised by a cramping pain in the leg which arises on exercise and goes away when the patient rests. This condition is caused by peripheral vascular disease. This refers to the peripheral vessels being damaged by atherosclerotic lesions. When these lesions are present, the vessels are narrowed and lose a great deal of their flexibility. The tissues in the body require a specific volume of blood to adequately carry out all of their necessary metabolic functions. In perihperal vascular disease, the vessels, due to their reduced flexibility and lumen diameter, are unable to supply the muscles in the leg with sufficient blood to carry out metabolic functions when increased demends such as exercise are placed upon them. This causes pain. When the patient rests, the metabolic needs of the leg muscles are reduced, hence the diseased vessels can supply sufficient blood and the pain disperses. Ginkgo has shown to considerably decrease ischemia in this condition and dramatically improve symptoms of this condition. This is most likely due to the previously disussed ability of this herb to ‘normalise’ (yes i DO hate this word!) vascular pressures and tissue perfusion.
Cognitive deficiency and dementia - Dementia is characterised by disturbances in higher cortical functions such as memory, thinking, orientation, comprehension, calculation and learning. This condition affects 10% of those over 65 and 20% of those over 80. As has been discussed, Ginkgo can improve the flow of blood to peripheral tissues, thus increasing blood perfusion to these tissues. When dementia is not related to specific neurological lesions, an increased blood flow can greatly improve the overall functioning of those particular tissues. Even where there is a specific lesion, improving blood flow will be beneficial as it will ensure that tissues are well oxidised and have a good supply of nutrients which may slow down their decline.
Tinitus - This condition is described as a continual high pitch noise that is heard without any external cause. It is caused by damage to the auditory pathway especially the cochlea. It can arise for a number of reasons including anaemia, hypertension, use of prescription drugs including aspirin and chloroquine. It can also be caused by continual exposure to loud noises (headbangers be warned!). A review of randomised controlled trials using Ginkgo in tinnitus patients where Gingko, a placebo, and another active drug were used, concluded that the overall results of these trials showed Ginkgo to be a statisticallly significant treatment for tinnitus (Boon & Smith 2003:148). I have seen this herb be used to considerable levels of success in treatment of this condition. However, this has mostly been in conjunction with other herbs such as Crataegus laevigata so how Ginkgo fairs on its own, or how much it contributed to this therapeutic outcome is unclear.
References
Barnes J, Anderson LA, Phillipson JD (2002). Herbel Medicines (2nd ed). UK,London: Pharmaceutical Press).
Boon H, Smith MS (2003). The natural medicines guide to the 50 most common medicinal herbs. Canada, Toronto: Robert Rose Inc.