Variety is the spice of…cognitive function

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.