Variety is the spice of…cognitive function

Photo by muammerokumus via Flickr.

Photo by muammerokumus via Flickr.

In September I introduced you to health sciences professor Katherine Tucker and the Boston Puerto Rican Health Study, a longitudinal research program aimed at studying the  relationships between stress and diet and their effects on cardiovascular disease and overall health among the urban Puerto Rican community in Boston. I plan to highlight, on a regular basis, research papers coming out of this Center for Population Health and Health Disparities, one of ten of its kind funded by the National Institutes of Health. This month we’ll look at a study published in the British Journal of Nutrition in May, 2012.

We all know how important it is to eat our fruits and veggies. When I was a kid, I remember the guideline being around five servings a day, but now I’m hearing nine. This is a problem for me, because I stink at eating fruits and vegetables. I try to stock my fridge, but usually the mold gets to it before I do. But perhaps I should change my approach, pending results recently published by health sciences professor Katherine Tucker: It turns out variety may be more important than overall number of servings.

Tucker and her team analyzed the behavioral and dietary patterns of 1412 Puerto Rican adults between the ages of 45 and 75 from the Puerto Rican Health Study.

In ongoing work, Tucker’s team had previously administered a food frequency survey to the cohort, asking how often they ate certain foods like beans, brown rice or hard cheese. The survey also asks about portion sizes and is specifically targeted to the Puerto Rican community, asking about such things as plantains and bacalao (salted cod), which aren’t found on traditional food frequency surveys.

Tucker’s team also developed analytical software for their survey that uses traditional Puerto Rican recipes to give more accurate nutritional estimates. When people of different cultures hear the word “rice,” for instance, very different things may come to mind. For some it may mean simply that: rice. But for others it may mean cut up vegetables, lots of butter and rice, and for most Puerto Ricans, rice cooked with corn oil.

The Puerto Rican Health Study also asks participants about their physical activity level and tests cognitive function. In this analysis, her team looked at things like memory, attention, and executive function.

After controlling for many factors including gender, education, acculturation (a measure of how often English is used in daily life), smoking and drinking habits, household income, body mass index, total energy intake, medication use, hypertension, diabetes, and physical disability, they found that the variety of fruits and vegetables a person eats, was more important than the total number of servings.

Those people who consumed twice the variety of their counterparts were 13% more likely to get a high score on the Mini Mental State Examination, which assesses global cognitive function. When it came to just vegetables, greater overall intake also had an effect. But fruit alone and the combination of the two required increased variety to see any benefits.

The work suggests that variety should be a more important target for those of us trying to do better with fruit and vegetable intake. The team notes that while the population surveyed here is limited to middle aged and older Puerto Rican adults, there’s no reason to think the same will not be true for other populations.