Ginkgo biloba: effects and side effects.

Date: Thu, 23 Feb 1995 09:15:04 +0000
Sender: Medicinal and Aromatic Plants discussion list <HERB.TREARN.BITNET>
From: Jonathan Treasure <jtreasure.JONNO.DEMON.CO.UK>
Subject: Re: Gingko biloba

>An acquaintance told me recently that after taking tablets of Gingko biloba extract (40 mg. 24% standardized) he experiences flushing of the face, pain at the base of the skull, headache, and extreme discomfort. Does anyone know why he would have such a reaction? Has anyone else had such "side effects"? He has discontinued use.

GB increases cerebral arteriole vasodilation - this lets more plasma than usual escape into the skull cavity which has no room for excess fluid and can only drain a limited aount (20ml/day) through its normal routes so pressure builds up - hence pressure headache, protruding eyeballs etc etc. These are the effects, not side effects.


From: Jonathan Treasure <jtreasure.JONNO.DEMON.CO.UK>

>> GB increases cerebral arteriole vasodilation -
> Is there, to your knowledge, any potential danger in this? He said he felt as if he were going to have a stroke.
> One more question--are those effects to be expected any time it is taken, or do they diminish over time--and can they be potentially damaging to some people?

The person taking Ginko extract was presumably "self-medicating". It is a by-product of the anomalies in herbal medicines legislation in the USA that herbs with complex effects that should be used with some degree of understanding of their actions are sold OTC to anyone - as Michael Moore has pointed out this opens up whole new vistas of *auto-iatrogenesis*. It may be fine to buy an OTC dandelion/yellow dock liver cleanse, but many herbs available freely OTC are potentially hazardous. in the UK for example Ephedra (Ma Huang) is a Schedule 3 Poison. but in the US it is commonly abused as a natural speed/slimming aid etc

The US supplements/herb products industry produces OTC Gb formulae such as GINKALERT etc marketed to persuade gullible students etc that their revision and exam performance will be helped if they consume it in copious quantities. The *wonder drug* image is enhanced by the some of the active constituents being antioxidant bioflavonoids and hence super-trendy. (I always thought free radical scavenger sounded like the republican right backlash myself) Anyway Not Suprisingly they get headaches.

The standardised product you refer to is a highly concentrated form of the plant, which has proven beneficial effects on short term memory in the elderly, possible applications in Alzheimer's, is specific for tinnitus, retards platelet aggregation (anticoagulant), heals head trauma neurological symptoms, and is used by herbalists to promote peripheral and cerebral circulation, especially in cases of arterial insufficiency, transient ischaemic attacks, etc etc.

Toxicologically Gb leaf extracts are considered benign - although the fruit can cause severe allergic reactions. Headaches are a rarely reported symptom, with GI symptoms also infrequently occurring. Normal doses of the standardised extract are 3x40mgm per day, athough this has been doubled without adverse effects in some recent clinical trials to 240mgm/day - not advised tho.

To answer your specific question, it is very unlikely IMO that Gb could cause your friend to have a stroke, quite the opposite, since it actually relaxes the tone of blood vessel walls, compensates for ischaemia (lack of Oxygen) and is anticoagulant (blood thinning) - indeed it is specifically indicated for CVAs (cerebro-vascular accidents). He may however have had a bad pressure headache and believed that he was going to have a stroke, which at least suggests that his body was telling him to stop taking the stuff..... often our bodies are more sensible we are he was either very sensitive, overdosing, or constitutionally contra to the herb. I do not know which.


From: Jonathan Treasure <jtreasure.JONNO.DEMON.CO.UK>

>What are the benefits of this cerebral arteriole vasodilation? This doesn't sound very pleasant.

Increased delivery of nutrients ie oxygen and glucose to brain cells.
Very handy in cases of cerebro-vascular insufficiency not unusual in the elderly