Eating berries can delay mental decline by up to two-and-a-half years, new research has found.

The study, published in the medical journal, Annals of Neurology, found women who ate at least half a cup of blueberries, or two-and-a-half cups of strawberries per week benefited most.

Brain ageing in participants was found to be delayed by about one-and-a-half to two-and-a-half years, compared to those who ate few or no berries, explained Waikato DHB geriatrician, Dr Phil Wood.

There's no explanation as to why women are more susceptible to mental ageing, but Dr Wood said the new study "may well be more important to females."


It's the antioxidant properties of berries that ward off cognitive deterioration - mainly a flavonoid called anthocyanidin - which acts as fire extinguisher preventing the process of brain cell death, Dr Wood said.

The study, recorded the diets of 16,000 nurses participating in the Nurse's Health study.

Lead author Dr Elizabeth Devore of Brigham and Women's Hospital and Harvard Medical School said the research provides "the first epidemiologic evidence berries may slow progression of cognitive decline in elderly women.

"Our findings have significant public health implications as increasing berry intake is a fairly simple dietary modification to test cognition protection in older adults," she told the Daily Mail.

Dr Wood said it's unfortunate the study only focused on females and the elderly population. He said the health benefits of eating a variety of coloured fruits and veges applies to everyone.

"You can't just say it's what the elderly should be doing, it's what we all should be doing."

"In fact I think if you want to develop a good diet, you really want to start at a young age because that's when your food habits develop."

The flavonoid antioxidant can be found in other foods such as bananas, oranges, apples, onions and tea, Dr Wood said.

"I personally think berries have a strong part to play because they have high concentration of these antioxidants, but you can find these things in other vegetables and fruits as well, and therefore, I think it's interesting that we have good colour vision."

It's not clear if fresh or frozen berries are best, but the European Food Information Council said berries frozen immediately after harvest still have much of their nutrients preserved.

A cautionary note on the study could be the concession by the authors who said they could not rule out the possibility women who ate more berries, also had other healthy lifestyle features, like exercise and income, which could have affected the overall findings, the Daily Mail reported.

Dr Wood said his personal philosophy is to adopt a balanced good quality diet, instead of jumping on one piece of research.

"This study's looked at blueberries but they haven't looked at a heap of other things as well, so you have to piece together science and these studies, and not make too much out of any one of them. You've just got to be sensible."