Fruits, Vegetables and Your Brain

We know from recent studies that following a Mediterranean-style diet reduces your risk of Alzheimer's and can also slow the normal decline in cognition as one ages. We've written about how drinking juice, a good source of polyphenols, can also help you reduce your risk of Alzheimer's, and we've also reported on how eating fish can also help you avoid mental decline.

Researchers in The Netherlands decided to look at the amounts of fruits and vegetables in one's diet and whether that would impact cognitive decline (Brit J Nutr 2011;5(106):752-761). They made use of information gathered in a long-term, large scale dietary study of over 7700 men and women who were between the ages of 20 and 59 at the start of the study, which began in 1987 and lasted through the present day.

In 1995, the study designers introduced cognitive testing for a random sample of those participants who were 45 or older. The first set of four standard cognitive tests was performed in between the years of 1995 and 2002, then 5 years later the same tests were performed again to a total of 2,613 men and women. On both occasions the participants responded to a food frequency questionnaire which asked them to report on their consumption of 178 different foods over the past year.

The researchers focused their attention on four specific food groups: fruits, vegetabes, legumes and juices, with subdivisions of each group (for example: "fruit" included both fruits and nuts, while "vegetables" was subdivided into leafy, fruiting, root vegetables, etc.). The amounts of each group that the participants ate was grouped into five categories of intake, from least to most, and then compared with that subject's scores in the cognitive tests. Finally the researchers compared the earlier cognitive scores with the later ones and correlated those with the individual's food intakes.

Their results are rather confounding. First, at the start of the study they found that those who reported that they ate the most vegetables processed information more slowly and were less mentally flexible than those who ate the least vegetables. On the other hand, after five years those who ate the least vegetables saw their mental abilities decline 2 times as much as those who ate the most vegetables.

Other groups and subgroups (specifically nuts, root vegetables and cabbage) had similar long-term effects, in the sense that higher consumption meant less decline.

What this means for you

This study focused on those who did not already have dementia or other cognitive problems and compared information gathered over the long term. While we can't say that eating more fruits and vegetables will definitely help you avoid the loss of your mental faculties or slow down the progression of dementia, this does give you yet another reason to eat more fruits and vegetables (as if you really needed any). Pick your favorites, eat them and enjoy them!

First posted: April 13, 3011