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Alternative therapies play an important part in the lives of some individuals. Many people put their trust in some aspects of these - but what is the evidence for their effectiveness?

A useful book which brings together a number of systematic reviews of alternative medical therapies [1] examines the evidence for effectiveness of alternative diagnosis (iridology), acupuncture, homeopathy, vitamin supplementation and plant products. Though from the excellent group with Paul Knipschild in Maastricht, the only problem for many will be that about 60% of the book is in Dutch.


One of the most interesting positive findings in the book is the evidence based on reviews of over 40 clinical trials that one alternative therapy, gingko extracts, are effective.

Extracts from the leaves of gingko biloba have been used therapeutically for centuries, especially in traditional Chinese medicine. Extracts of leaves and other parts of the tree can be made into tea. Extracts can be partially purified and dried, and a number of gingko preparations are used widely in some European countries.

The extracts contain a number of complex organic molecules, including a family of gingkolides. These are know to be platelet-activating factor antagonists (PAF-antagonists), a group of substances with an interesting chemistry and some fascinating therapeutic potential in a range of clinical conditions with effects on the nervous system, inflammatory disorders and reproduction [2,3].

The main indications for gingko are peripheral vascular disease such as intermittent claudication and "cerebellar insufficiency". This latter is an imprecise term that describes a collection of symptoms, especially in elderly people:-
Difficulties of concentration and memory
Lack of energy
Decreased physical performance
Depressive mood
These are associated with impaired cerebral circulation.

Systematic review

Forty clinical trials were found for gingko extract used in cerebral insufficiency, of which eight were high quality [4]. The results were homogeneous - virtually all produced positive results for gingko extract taken at about 120 mg a day for 4 - 6 weeks. Adverse effects are reported as rare.

Details of the results of gingko extracts in the eight quality trials in cerebral insufficiency and the two good studies in intermittent claudication have also been given [5].


These reviews have concentrated on the methodological quality of the studies, and have abstracted a number of high quality studies which predominantly favour gingko extracts over placebo for the outcomes chosen. The magnitude of the increased effects is often quite large.

It is slightly frustrating that the potential impact of gingko as a treatment or dietary supplement does not come over. It may be quite important. Given that it appears safe, positive effects on some of the symptoms of "cerebral insufficiency" in the growing number of elderly people in Britain could have profound benefits.


  1. J Kleijnen, G ter Riet, P Knipschild. Effectiviteit van alternatieve geneeswijzen: Ein literatuuronderzoek. Rijkuniversiteit Limburg 1993. ISBN 90-74130-09-7.
  2. M Koltai, D Hosford, P Guinot, A Esanu, P Braquet. Platelet activating factor (PAF). A review of its effects, antagonists and possible future clinical implications (Part I). Drugs 1991 42: 9-29.
  3. M Koltai, D Hosford, P Guinot, A Esanu, P Braquet. PAF. A review of its effects, antagonists and possible future clinical implications (Part II). Drugs 1991 42: 174-204.
  4. J Kleijnen, P Knipschild. Gingko biloba for cerebral insufficiency. British Journal of Clinical Pharmacology 1992 34: 352-8.
  5. J Kleijnen, P Knipschild. Gingko biloba. Lancet 1992 ii: 1136-9.

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