Wednesday, July 21, 2010

Substance Review: Ginkgo Biloba

Ginkgos are deciduous trees that are ancient enough to be considered living fossils and have been found in the fossil record across the world. They are primarily associated with Asia where the only remaining wild Ginkos grow and where the plant got its reputation as a Traditional Chinese Medicine (TCM).

Ginko's earliest mention is in the "Shen-nung pen-ts'ao ching" as an aid for circulation and breathing. Since then various applications of its fruit, leaves and bark have been administered for a range of conditions until eventually Ginkgo found its way to western medicine in the 1950s. In modern alternative medicine it is found as an extract of the fan-like leaves and most often used as a way to enhance learning, help prevent Alzheimer's and improve mood. It has reached quite popular levels with an estimate 2% of the American population using it as a herbal remedy.

Its not documented with any reliability as to how Ginkgo Biloba works, but its modern application focuses on the flavanoids or biologically active material in the leaves known as ginkgolides and bilobalides. It is theorised that these flavanoids are GABA antagonists, which means they stop or slowdown neurotransmission. A light inhibition of nuerotransmission is associated with a reduction of anxiety and a possible maintainance of concentration, while increased inhibition leads to sleepiness.

Physical effects:
If ginkgo creates this calming effect, it may be useful as a nerve settler before a big match or event, but this could come at the cost of feeling lethargic. Of more concern is Ginko's reported side-effects, in particular intercranial bleeding. A comprehensive meta-analysis showed that there was a link between gingko and spontaneous bleeding, though this was most strogly associated with participants who had existing conditions.

Cognitive effects:
For our purposes, Alzheimers is of no true relevance to the improvement of sports specifically so we should focus on ginkgo's purported learning, memory and mood enhancement. That is not to say we will ignore mature atheletes (a category where one of the better gingko studies showed some promise), only that it does not follow that older atheletes will have Alzheimers so it is of no direct benefit to sport.

The amassed research for Gingko is formed of equal parts for and against the herb as a cognitive enhancer. If you stick to the research with best-practice methodologies and ignore the more theoretical studies on rats or small samples of participants, the evidence tends to sway away from any significant cognitive benefit. A popular supplement company's gingko formula was tested to no effect. Similarly a Swedish trial found no impact on memory or learning. That said, a British trial found that Gingko improved quality of memory, while significantly hampering speed of attention. Also in one of the more reliable positive studies ginkgo was found to enhance sustained attention and pattern recognition, however after 6 weeks this enhancement was lost. I would question as to whether it washed out or if it was merely chance and other factors that improved memory attention at the beginning of the trial.

Ginkgo biloba, may have some very specific cognitive benefits, but it is unlikely. Older athletes looking to stay on top of there game might benefit from cognitive enhancement in remembering and sustained application of say a triathlete's race plan. Younger athlete's might not gain any real benefits from gingko biloba and any they do may well wash out after minimal use. The well conducted trials all point to a distinct lack of evidence for cognitive enhancement, depsite what is touted by TCM and when you consider its genesis in this field was as a blood circulator it hardly seems surprising. Under no circumstance would I recommend gingko as a supplement for martial artists or participants in contact sports. There is a significant correlation between ginkgo and exacerbating bleeding, in particular intercranial bleeding. The risk isnt worth the reward.

What to watch out for:
Sometimes its put in with other herbal remedies and while it may not necessarily be of a significant dosage its good to keep an eye out for:

  • Ginkgo biloba is sometime mislabelled as gingko
  • Yin Xing
  • Maidenhair derivatives

Further reading:

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