British blackcurrants are said to be especially rich in anti-oxidants
Compounds in the common British blackcurrant could help prevent Alzheimer's disease, research suggests.
A study shows blackcurrants and an American fruit boysenberries, are full of potentially beneficial anti-oxidant compounds.
Research in the Journal of Science Food and Agriculture found these compounds could block the cell damage which leads to Alzheimer's disease.
The New Zealand team said the berries could prevent but not cure dementia.
Cancer and ageing
Alzheimer's disease is thought to be caused by the build up of deposits of a protein in the brain.
These amyloid plaques are associated with damage to brain cells, which are eventually killed off.
It is this damage - known as oxidative stress - which the anti-oxidant compounds in the berries appears to combat.
The berries contain a cocktail of chemical compounds including anthocyanins - which cause the deep colour in blue and purple fruits - and polyphenolics - which can be found in red wine and chocolate.
Dilip Ghosh of the Horticulture and Food Research Institute of New Zealand tested the compounds on cultured human brain cancer cells.
They demonstrated in a test tube their ability to protect against the effects of oxidative stress - in this case caused by adding the chemical hydrogen peroxide to the culture.
Oxidative stress is an important cause of brain degeneration as well as cancer and ageing.
The researchers said: "The extracts of boysenberry and blackcurrant containing anthocyanins and phenolic compounds displayed significant inhibition against the oxidative challenge of hydrogen peroxide."
This can decrease the rate at which cells mutate and therefore give protection against age-related diseases, they added.
Fellow researcher James Joseph of Tufts University said the effect was likely to be the same in humans.
He told Chemistry and Industry magazine: "I am confident that the Alzheimer's protective effect we've seen will bear out in live humans.
"Diet will never be able to cure Alzheimer's but could prevent it or at least delay its onset."
Head of research at charity Alzheimer's Society Dr Susanne Sorensen said the study results helped to explain evidence that berries have a protective effect against a range of diseases.
She said: "The results demonstrate that a specific fraction of blackcurrant is particularly effective in this respect.
"However, the results cannot readily be transferred from this experimental system of cultures of well characterised tumour cell lines to neurons nor to complete brains."