Trending Clinical Topic: Ultra Processed Food

Ryan Syrek


August 12, 2022

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Diets high in ultraprocessed foods (UPFs) have long been known to cause a myriad of health issues. Recently, that myriad has gotten even bigger. Soft drinks, ice cream, sausage, deep-fried chicken, certain condiments, packaged breads, flavored cereals and more have now been linked to dementia and poor mental health (see infographic below). The new evidence sparked newfound interest in UPFs, resulting in the week's top trending topic.

A prospective, cohort study found that not only do UPFs increase dementia risk, replacing them with unprocessed or minimally processed foods decreases risk. Researchers analyzed 72,083 individuals from the UK Biobank, with a mean age of 61.6 years. All were free of dementia at baseline. Over 10 years of follow-up, 518 participants developed dementia. Of these, 287 developed Alzheimer's disease, 119 developed vascular dementia, and 112 developed dementia of unspecified origin. On average, UPFs comprised 9% of the daily diet of people in the lowest consumption group (an average of 225 g/d). In the highest consumption group, UPFs accounted for 28% of the daily diet (814 g/d).

Compared with those who consumed the least amount of UPFs, the dementia risk among those with the highest consumption was increased by 50% (hazard ratio [HR], 1.51; 95% CI, 1.16-1.96; P < .001). Their risk of developing vascular dementia was increased more than twofold (HR, 2.19; 95% CI, 1.21-3.96; P < .01). Beverages were the main "food group" contributing to UPF intake, accounting for 34%. The next most common was sugary products (21%), then dairy products (17%) and salty snacks (11%). Researchers determined that if a person substituted 10% of the UPFs they habitually consumed with unprocessed or minimally processed foods, it would result in a 19% lower risk for dementia (HR, 0.81; 95% CI, 0.74-0.89; P < .001) and a 22% lower risk for vascular dementia (HR, 0.78; 95% CI, 0.65-0.94; P < .01).

A separate study presented at the Alzheimer's Association International Conference 2022 confirmed the toll that UPFs take on the brain. Results from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) showed that higher intake of UPF was significantly associated with a faster rate of decline in both executive and global cognitive function. Goncalves and colleagues evaluated longitudinal data on 10,775 adults who were grouped according to UPF consumption quartiles (lowest to highest). During a median follow-up of 8 years, UPF intake in quartiles 2, 3, and 4 (vs quartile 1) was associated with a significant decline in global cognition (P = .003) and executive function (P = .015).

"Participants who reported consumption of more than 20% of daily calories from ultraprocessed foods had a 28% faster rate of global cognitive decline and a 25% faster decrease of the executive function compared to those who reported eating less than 20% of daily calories from ultraprocessed foods," Goncalves reported. "Considering a person who eats a total of 2000 kcal a day, 20% of daily calories from ultraprocessed foods are about two 1.5 oz bars of KitKat, or five slices of bread, or about a third of an 8.5-oz package of chips," she explained.

A 2021 study found that UPFs were associated with a 22% increased risk for future depression, which took 2-10 years to develop. The effect the unhealthy food has on mental health continues to be elucidated. The precise reason why UPFs are associated with depression and similar conditions is unclear, but a leading theory involves the effect on the gut microbiome and associated inflammation.

Long-term impact on brain health from UPFs is especially concerning when considering that they account for most energy intake by young people in the US. Last year, a large cross-sectional study of National Health and Nutrition Examination Survey (NHANES) data showed that in young people aged 2-19 years, the estimated percentage of total energy from consumption of UPFs increased from 61.4% to 67.0% (95% CI, 3.5-7.7; P < .001 for trend). In contrast, total energy from unprocessed or minimally processed foods decreased from 28.8% to 23.5% (difference, -5.3%; 95% CI, -7.5 to -3.2; P < .001 for trend).

Although no one solution will curb the consumption of UPFs, the value of a warning label has been debated. The NOVA system divides foods into different categories: fresh or minimally processed (eg, strawberries, steel-cut oats); processed culinary ingredients (eg, olive oil); processed foods (eg, cheeses); and UPFs. According to doctors who participated in a virtual conference session sponsored by the American Society for Nutrition, because obesity and poor health are skyrocketing, increased awareness and labeling of UPFs can only be a good thing. In contrast, others noted that the NOVA Food Classification system is too mushy, confusing, and ultimately unhelpful.

Perhaps the best dietary solution is the easiest. As David A. Johnson, MD, suggests, "You can still have your occasional cheeseburger and French fries but use common sense." With more and more evidence mounting about the dangers of UPF, including findings about increased mental health and dementia risks, perhaps common sense will soon take over.

Learn more about dementia pathology.


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