Fruit juices are good for the brain

A surprisingly close link has emerged between drinking fruit and vegetable juices and avoiding Alzheimer's Disease.

US and Japanese researchers followed almost 2,000 people for up to 10 years and found the risk of Alzheimer's was 76% lower for those who drank juice more than three times a week, compared to those who drank it less than once a week.

Lead researcher Dr Qi Dai of Vanderbilt University told the BBC: 'We found that frequent drinking of fruit and vegetable juices was associated with a substantially decreased risk of Alzheimer's disease. These findings are new and suggest that fruit and vegetable juices may play an important role in delaying the onset of Alzheimer's disease.'

In the study, the benefit appeared particularly marked in people with a higher genetic risk of the disease.

Alzheimer's is linked to the accumulation of clumps of protein in the brain. Previous studies have suggested that polyphenols might disrupt the formation of clumps and neutralise the effects of free radicals. Fruit and vegetable juices are very rich in polyphenols.

However, they are not the only foods rich in these chemicals. In April research was published suggesting that the so-called Meditteranean diet - rich in fruit, vegetables and wholegrain cereals with some fish and alcohol and rather less dairy and meat — could reduce the risk of Alzheimer's. Extra-virgin olive oil is high in polyphenols.

At the time Professor Clive Ballard, director of research at the UK's Alzheimer's Society, said that a strong adherence to a healthy diet could reduce the risk of developing Alzheimer's disease by as much as 40%, emphasising the importance of healthy eating.

Which juices?

Unfortunately the researchers didn't ask what juices were drunk but they were most likely tomato, orange and grapefruit. Having said that, the fruits with the highest concentrations of polyphenols include strawberries, lychees, grapes, prunes and pomegranates. Vegetables with the highest polyphenol concentration include artichokes, parsley, and brussels sprouts.

A French study found that total polyphenol intake from fruit is about three times higher than from vegetables, due to the lower polyphenol concentration in vegetables. This is probably in part because most of the benefit is in the skin.

Obviously, fresh juices are better than factory-pressed verisons which appear to reduce polyphenol content. Green tea is also high in polyphenols.

Commenting on the latest research, Harriet Millward, of the Alzheimer's Research Trust, said: 'Many scientists believe there is a link between the release of free radicals within the body and early changes to brain cells in people who ultimately go on to develop Alzheimer's disease. Since fruit and vegetable juices are rich in antioxidants which 'mop up' free radicals, this interesting piece of research adds weight to this theory.'

Some previous studies have suggested that benefits of fruit and vegetables are short lived. But this study is worth taking note of as it was long-term study and involved quite a large group of people. Conversely, no association in this study was observed for vitamins E, C, or beta-carotene or regular tea.

The known risk factors for dementia are age, a low-level of education, high blood pressure, high cholesterol and obesity.