CHEMICALS in fruit and vegetables, as well as tea and red wine, could help to protect the brain against Alzheimer's disease, a conference will hear today.

Flavonoids - chemicals found in plants and food made from plants - have long been studied for their beneficial effects on people's health.

The British Pharmacological Society's summer meeting in Edinburgh will hear that, while more research needs to be done, there is mounting evidence that certain flavonoids might help Alzheimer's patients.

Dr Robert Williams, a biochemist at King's College London, said: "There have been some intriguing epidemiological studies that the consumption of flavonoid-rich vegetables, fruit juices and red wine delays the onset of the disease.

"These reports, while not as powerful as controlled, randomised, clinical trials, have encouraged a number of research groups, including our own, to investigate the biology of flavonoids in more detail."

Flavonoids are powerful antioxidants - compounds capable of protecting body cells from damage - known to benefit the heart and possibly reduce the risk of cancer. But there is a question mark over their influence on the brain. Dr Williams said the lack of research and clinical trial results meant research into flavonoids had suffered from a lack of scientific credibility.

He said there was also scepticism because flavonoids were known antioxidants, yet clinical trials with other antioxidants, such as vitamin E, showed no benefit on symptoms or disease progression in dementia.

However, Dr Williams said an idea was emerging that flavonoids did not act simply as antioxidants, they exerted their biological effects through other mechanisms.

Recent studies have found green tea flavonoids or grape flavonoids could help the brain and improve mental skills. Dr Williams and colleagues have focused on the flavonoid epicatechin, which is abundant in foods, including cocoa.

He said: "We have found that epicatechin protects brain cells from damage, but through a mechanism unrelated to its antioxidant activity, and have shown in laboratory tests that it can also reduce some aspects of Alzheimer's disease pathology.

"This is interesting because epicatechin and its breakdown products are measurable in the bloodstream of humans for a number of hours after ingestion, and it is one of the few flavonoids known to access the brain, suggesting it has the potential to be bioactive in humans."

In Scotland, it is estimated up to 67,000 people have dementia. By 2031, this number is expected to rise as high as 114,000.

The disease's development is linked to beta-amyloid peptide - a substance that is normally produced in the brain, but in Alzheimer's is deposited abnormally as amyloid plaques, leading to dementia.

Dr Williams has shown that flavonoids can protect brain cells against the toxic actions of beta-amyloid.

He said: "Although our findings support the general concept that dietary intake of flavonoid-rich foods or supplements could impact on the development and progression of dementia, they are clearly insufficient to make any sort of nutritional recommendations at this stage.

"The challenge now is to identify the single flavonoid or combination of flavonoids that exert the most positive effects and to define the mechanisms of action and optimal quantity required, before embarking on clinical trials to treat their effectiveness in dementia."

Kirsty Jardine, from charity Alzheimer Scotland, said: "We would advise people to eat a balanced diet, because there is evidence this helps reduce the risks of dementia. We look forward to further research into flavonoids to find out more about the benefits they offer."

'ALLERGY GENE' SUSPECT FOUND

DEFECTS in a particular gene are linked to a higher risk of allergic conditions such as eczema and asthma, researchers said yesterday.

The search for an "allergy gene" has previously proved difficult for researchers.

But studies have pointed to the filaggrin gene as a potential suspect.

Researchers from Edinburgh University analysed 24 studies looking at mutations in this gene and the link to allergic disorders.

They found that the mutations significantly increased the risk of conditions such as eczema, rhinitis and asthma.

The researchers, writing in the British Medical Journal, said: "These findings provide strong supporting evidence that, at least in a subset of those with allergic problems, the filaggrin gene defect may be the fundamental predisposing factor not only for the development of eczema but also for the initial sensitisation and progression of allergic disease."

They said more studies were needed to find if the gene could be used to identify those at high risk.