Reseachers have reviewed over 1000 studies looking into the benefits of supplementing with anthocyanins  – a type of flavonoid found in almost all fruits and vegetables but are particularly high in berry fruits. Flavonoids are powerful antioxidants with anti-inflammatory and immune system benefits– which are considered to helpful in lowering the risk of cognitive decline.

The review was carried out to provide a comprehensive overview of the many dietary intervention trials that have described the effects of berries on cognitive performance in humans.

Significant improvements were observed on memory and some studies also reported beneficial effects on attention and psychomotor speed (the relationship between cognitive functions and physical movements.)

Some studies also reported improvements in blood pressure and vascular function (blood flow to the tissues of the body) although further studies are warranted.

In the USA a small study of both men and women who had been diagnosed with ‘mild cognitive impairment’ – memory lapses that have the potential to develop into full-blown dementia – were given a blueberry powder supplement that contained the equivalent of a small teacupful of fresh fruit.

The volunteers were put through a series of mental tests at the beginning and end of the study, with a focus on memory and thinking skills that are affected by dementia.

One of the researchers said: ‘There was a significant improvement in cognitive function in those who had the blueberry powder, compared with those who took the placebo.’

Brain scans showed the brain was more active in those who had taken the blueberry powder which the researchers believe are due to the the benefits of anthocyanins, the plant chemicals that give the berries their deep blue/purple colour.

It is believed they act on the brain by boosting blood flow, cutting inflammation, and enhancing the passage of information between cells. The chemicals may also boost the defence mechanism of cells.

Dietary help

In the absence of medications that can prevent or cure Alzheimer’s or dementia it would appear to be beneficial for at risk individuals to modify their diets to include these important plant compounds.

Dr Krikorian said: ‘I believe that berry supplementation and, in particular, blueberry supplementation, may reduce the risk for late-life cognitive decline. The minimum dose is not clear but data suggest that taking blueberries several times a week should be beneficial.’

Dietary sources of anthocyanins:

  • blueberry, cranberry and bilberry  
  • Red/blue fruits: raspberry and blackberry, blackcurrant and redcurrant, cherries and black grapes.
  • the skin of dark purple aubergines
  • black rice
  • red cabbage

 Other health conditions that can be helped by anthocyanins

Anthocyanins have also been shown to be beneficial to eye health by enhancing visual acuity; for cancer by reducing cancer cell proliferation and inhibiting tumour formation; heart protective by reducing inflammation, enhancing capillary strength and permeability and inhibiting platelet formation.

So it seems that dark blue fruits and veg have earned their description of superfoods and we would all benefit by ensuring we include them in our diets.