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Too much junk food increases Alzheimer's risk

It is known for some time that diet quality is inversely associated with the risk of overall dementia. For example, people who eat two sausages or a burger every day have a high risk of developing Alzheimer's disease. Recent large scale studies (published in 2022) now confirm this hypothesis and reveal that people who eat a quarter of their calories from processed foods are 28% more likely to suffer cognitive complications than those with lower sugar and fat intakes.

Over recent decades, the consumption of ultraprocessed foods (UPF, colloquially called junk food) has increased dramatically worldwide due to the fact that they are easily accessible, tasty, and affordable. These include cookies, deep-fried snacks, ice cream, candy, cream cheese, white bread, sausages and other processed meat products, and soft drinks. Previous research has found that, on average, more than half of an American's diet consists of processed foods containing more than 5 commercial preparations. Generally, UPF are energy dense (high in added sugar, fat, and salt) and low in protein, polyunsaturated fat, and soluble fibers. Importantly, UPF contain newly formed molecules produced during heating, food additives used in manufacturing, and molecules dissolved from packaging materials, all of which have shown adverse effects on cognitive function in experimental and population studies.

As part of the new studies, researchers examined the dietary habits of 10,000 adults in Brazil to determine if their food intake affected their brain function. The proportion of these foods is very high; according to a 2016 study, they account for about 58 percent of all calories consumed in the U.S.. In Brazil, the share of these foods is more like 25 to 30 percent, as the authors of the study now presented estimate. No data are known for Austria in this regard, but there are studies that young people in particular are eating more junk food and that consumption may have increased overall during the Covid pandemic. Slightly more than half were women, white or college graduates, and the average age of the subjects was 51. Cognitive tests were administered at the beginning and the end of the study, which included immediate and delayed word recall, word recognition and verbal fluency, and participants were asked about their diet.

The researchers found in one study that participants who ate more processed foods had a nearly 30% higher risk of experiencing cognitive complications. Participants who met 20 percent or more of their daily caloric intake from highly processed foods were found to have a more rapid decline in cognitive performance over a six- to ten-year period than those who consumed fewer processed foods. In addition, those who ate a lot of processed foods were at higher risk for impaired executive function, which made it more difficult to process information and make decisions. This could trigger inflammatory processes or lesions in the brain which can increase the speed of the cognitive decline.

In another study a 10 percent increase of UPF in the diet was associated with significant increases of 25% in the risk of overall dementia, 14% in the risk of Alzheimer's disease, and 28% in the risk of vascular dementia (all values adjusted for age, sex, ethnicity, education, smoking status, drinking status, physical activity, body mass index, sleep duration, history of cardiovascular disease, family history of dementia, total energy intake, and healthy diet score). The authors of these correlative studies did not conclude, however, that eating highly processed foods was a direct cause of the observed cognitive decline. This needs to be investigated in future studies.

The message we should take away from these data is easy: Stop buying things that are super-processed and do not forget that the recommended daily caloric intake is 2,500 for men and 2,000 for women (according to the Centers for Disease Control and Prevention).


Ferreira, N.V., Lotufo, P.A., Marchioni, D.M.L., Barreto, S.M., Viana, M.C., Caramelli, P., Bensenor, I.J.M., and Suemoto, C.K. (2022) Association between adherence to the MIND diet and cognitive performance is affected by income: The ELSA-Brasil Study. Alzheimer Disease & Associated Disorders 36:133

Li, H., Li, S., Yang, H., Zhang, Y., Zhang, S., Ma, Y., Hou, Y., Zhang, X., Niu, K., Borné, Y., and Wang, Y. (2022) Association of ultraprocessed food consumption with risk of dementia. A Prospective Cohort Study 99:e1056

Martínez Steele, E., Baraldi, L.G., Louzada, M.L.D.C., Moubarac, J.-C., Mozaffarian, D., and Monteiro, C.A. (2016) Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study. BMJ Open 6:e009892

Image credit: iStock/elenabs


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