An article earlier this year in the European Journal of Nutrition reported that high consumption of ultra-processed foods is linked to worse-than-average performance on one particular test of cognitive function in older US adults (60+ years-old) who did not have chronic diseases such as diabetes or cardiovascular disease. The particular test was “Animal Fluency.” Never heard of it? Me either. Keep reading.
The study included 2,700 participants, average age 69. Participants were asked to recall what they ate in the prior 24 hours. Foods were “classified according to NOVA, a food classification based on the extent and purpose of industrial food processing, into four mutually exclusive groups: (1) unprocessed or minimally processed foods, (2) processed culinary ingredients, (3) processed foods, and (4) UPFs [ultra-processed foods].”
Ultra-processed foods? “…most foods described as “Frozen meals” or “Lunchables”, as well as some items described as consumed in “Restaurant fast food/pizza” or acquired at a “Vending machine” were classified as UPFs.” Furthermore, the authors write in the introduction that “UPFs, according to the NOVA classification system, are industrial formulations of processed food substances (oils, fats, sugars, starch, and protein isolates) that contain little or no whole food and typically include flavourings, colorings, emulsifiers, and other cosmetic additives. UPFs are becoming dominant in diets globally and are replacing traditional diets based on unprocessed and minimally processed foods.
Of the entire study population at hand, UPFs were about half of all calories consumed but ranged from 30 to 70%.
“Cognitive performance was assessed using the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD), Word Learning test, Animal Fluency test, and the Digit Symbol Substitution test (DSST).”
The Animal Fluency test “evaluates categorical verbal fluency (executive function).” “For the Animal Fluency test, the participant is requested to name as many animals as possible within a 60-s [60 seconds, I assume] time period. Each animal corresponds to 1 point and the result is presented as the total sum of points.”
The test subjects were given two other tests of cognitive function but the investigators found no differences in performance based on ultra-processed food consumption. Here are these other two tests:
The two parts of the CERAD Word Learning test consist of (1) three consecutive learning trials, where the participant was requested to recall a list of ten unrelated words immediately after their presentation. Each word corresponds to one point, and the result is presented as a total score across the three trials (range 0–30); and (2) a delayed word recall test, performed after the two other cognitive tests. The result ranges from 0 to 10. … For the DSST, the participant is presented a single sheet of paper where they are asked to match a list of nine symbols to numbers according to a key located on the top of the page. The task had 133 numbers and the participant had 2 min to complete it. The result is shown as the total number of correct matches. For all the tests, higher scores represent better cognitive function.
The authors conclude: “Consumption of UPF was associated with worse performance in Animal Fluency, a cognitive test that assesses language and executive function in older adults without pre-existing diseases such as CVD [cardiovascular disease] and diabetes, while no associations were observed for those with these conditions. While longitudinal studies are required to provide stronger evidence, these results suggest that decreasing UPF consumption may be a way to mitigate age-associated cognitive decline and reduce the risk of dementia.”
I agree these results aren’t very strong.
Steve Parker, MD
h/t Jan at The Low Carb Diabetic blog