Positive results may eventually lead to British doctors prescribing the supplement for people with age-related memory loss, benefiting suppliers of high-quality products who have been suffering from growing sales of the supplement in mass market channels.
Extracts of the ancient Chinese plant Gingko biloba have been prescribed for some 20 years for cardiovascular problems by doctors in Germany and France, as the plant has been shown to improve blood flow and thin the blood, making it less likely to clot.
As a result, ginkgo has been one of the top ten pharmaceuticals in these markets until recent cutbacks in national healthcare scaled down reimbursements for prescription products.
Outside these markets however, gingko is more likely to be bought as a supplement from health food shops or supermarkets, than recommended by doctors. And these outlets are the ones driving sales of the herbal, which is thought to be increasing in annual tonnage by 2-3 per cent. The raw material comes almost entirely from growers in China.
"In markets where it is sold as a dietary supplement, like the US, UK and Australia, sales are expanding due to the quality of product available," Massimo Lattuada, sales and marketing director for Italian firm Indena, told NutraIngredients.com.
"It is getting cheaper because many of these markets have no regulations in place to enforce the quality of the raw material."
He added that future European regulations focus on the quality of the finished product rather than beginning with the raw material. "The emphasis should go on what goes into the tablets and capsules. It's fine having nice-looking capsules but you don't know what is inside."
When the quality of the ingredient varies, it may not deliver consistent activity or the same results, said Lattuada, and the researchers on the new trial agree.
The team at Imperial College London is using the gingko extract EGb 761, manufactured by German company Schwabe. The company has not been involved in the study - the product has been purchased by the researchers with funding from a charity - but the firm is one of the largest suppliers of gingko in Europe and its product one of the most widely researched.
"If we find it to be effective, we would advise the use of a high-quality product, although we wouldn't recommend specific brands," said Robert McCarney, research associate on the study. "A lot of people still don't appreciate the quality of supplements and just look for the price, but studies have shown a lot of variation in the quality of herbal supplements."
The new study will be one of the first to test gingko as a treatment for those who are still living in the community and who have been diagnosed with early dementia by their GP.
"There have been a number of trials carried out on gingko but most of these have recruited from secondary care, where the condition is often more advanced," explained McCarney. In a community setting, patients' symptoms are usually less severe.
Study leader Dr James Warner, a psychiatrist from Imperial College London and St Mary's Hospital, added: "This trial will help us to find out whether with gingko it's a case of 'the sooner the better', for patients who may benefit from taking it."
The new trial could lead to increased recommendation, or even prescription, by British doctors, benefiting sales of the higher quality gingko brands.
"All positive research is good press and will benefit everyone. But in the long-term, the serious players will benefit most," predicted Lattuada.
At its peak a few years ago, the wholesale market for gingko biloba in France and Germany was estimated to be worth $500 million, he added.
It is estimated that 700,000 people in the United Kingdom are affected by dementia, 60 per cent of whom are diagnosed with Alzheimer's disease. Gingko would provide a cheaper alternative to conventional medicines, with fewer of the potential side effects such as nausea, loss of appetite, tiredness and diarrhoea. A quality gingko extract costs around £200 for a year's supply while conventional medicines for memory loss, drugs known as cholinesterase inhibitors, cost around £1,000 a year, and prescription of these drugs is restricted.
Gingko is believed to cause blood vessels to dilate, improving blood flow to the brain, and may also have antioxidant effects, protecting nerve cells against biological 'rusting'. All of these effects would suggest that gingko might slow down a degenerative process such as dementia, said Dr Warner, and there is already some evidence to support this effect.
"There hasn't been a head-to-head trial between gingko and cholinesterase inhibitors but previous results suggest they may be similar in slowing down progression of the disease. Gingko seems to have less side effects though," said McCarney.
He added that such a trial would be useful, as well as further research into the ideal dose of the herbal.
The new double-blind, placebo-controlled study is recruiting 250 patients aged over 55 with early symptoms of dementia. Results are expected in 2006.