June 4, 2026, 6:03 pm | Read time: 5 minutes
Ready meals, soft drinks, and sweet snacks are unfortunately a staple in many people’s daily lives. According to a new study from Harvard University, a high consumption of such highly processed foods could impair brain health in old age and thus increase the risk of dementia. Participants with the highest consumption were more frequently affected by dementia and other cognitive impairments. In contrast, a high proportion of unprocessed foods in the diet was associated with a lower risk.
How Was the Study Conducted?
For the study, Harvard researchers analyzed data from 5,370 Americans aged 50 and older who participated in the long-term “Health and Retirement Study.”1 At the start of the study, all participants had neither dementia nor other memory problems. Individuals who developed cognitive impairments shortly after the study began were excluded from the analysis to avoid skewing the results.2
The researchers recorded the participants’ eating habits once in 2013 using a detailed questionnaire. The focus was on the consumption of so-called ultra-processed foods. These include soft drinks, sweets, breakfast cereals, ready meals, or processed meats. Established criteria were used to determine how high the proportion of these heavily industrially processed products was in the daily diet.
The researchers then followed the participants for nearly nine years. Between 2014 and 2020, their cognitive performance was assessed every two years using standardized memory and thinking tests. This allowed the researchers to track whether dementia or milder forms of cognitive impairment developed over time.
In their evaluation, the research team considered numerous factors that can influence the risk of dementia. These included age, gender, education level, and income. Smoking and drinking habits, physical activity, and existing illnesses were also included in the analysis. The researchers then compared the risk of dementia and cognitive impairments between people with low and high consumption of ultra-processed foods.
Dementia Risk Significantly Increased
During the nearly nine-year follow-up period, 266 participants developed dementia, and another 1,191 developed mild cognitive impairment without dementia. The results indicated a significant link between the consumption of ultra-processed foods and the risk of cognitive decline.
Those with the highest consumption of heavily processed products had a 58 percent higher risk of dementia compared to participants with the lowest consumption. The risk of mild cognitive impairments was also 46 percent higher. When both conditions were considered together, there was a 47 percent increased risk. Notably, as the proportion of ultra-processed foods in the diet increased, so did the risk of cognitive problems.
The link was particularly pronounced with processed meat. Participants with the highest consumption had more than double the risk of dementia compared to those who ate little of it. Conversely, those who primarily consumed unprocessed or minimally processed foods like fruits, vegetables, and other fresh products benefited. Their risk of developing dementia over time was 41 percent lower.
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What Does This Mean Specifically?
The results suggest that not only the nutrients of a food are important. Its degree of processing could also play a role in brain health. People who regularly consume many heavily processed products could have a higher long-term risk of dementia and other forms of cognitive decline. Participants who consumed particularly many unprocessed or minimally processed foods like fruits and vegetables had a significantly lower risk of dementia.
It is also interesting that the study found no evidence of a clearly “safe” consumption level of ultra-processed foods. Even moderate amounts were associated with an increased risk of cognitive problems. The authors see this as further evidence that the quality of the diet could play an important role in healthy aging.
However, the study does not prove that ultra-processed foods directly cause dementia. As an observational study, it can only show correlations. Nevertheless, the results are consistent with numerous previous studies that have already linked heavily processed foods to obesity, diabetes, cardiovascular diseases, and other health problems.
Given the worldwide increase in dementia cases, such findings could be particularly relevant for prevention. The study suggests that even small changes in everyday life–such as fewer ready meals and more fresh foods–could contribute to maintaining cognitive performance in the long term.
Also interesting: These Dementia Risk Factors Are Already Evident in 20-Year-Olds
Context and Possible Limitations
The study scores with its large number of participants and the long observation period of almost nine years. This allowed the researchers to track possible links between eating habits and later cognitive diseases over a longer period. However, it is an observational study. This means that while the results suggest a connection, they cannot prove that ultra-processed foods are directly responsible for the increased risk of dementia.
The dietary data were collected via questionnaire, and the recording of dementia and cognitive impairments was not done through clinical examinations but using a validated testing procedure. Both can be associated with certain inaccuracies. Nevertheless, the authors consider their results to be robust.
Additionally, the participants’ eating habits were recorded once in 2013 using a detailed questionnaire and served as the basis for further analysis. The authors point out that such survey methods can be associated with inaccuracies and therefore represent a limitation of the study.