June 24, 2026
ByJoyce Hendley,
Staff Writer
- Reviewed byRobert H. Shmerling, MD,
Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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If you’re concerned about keeping your brain healthy as you age, here’s one more reason to take a hard look at what’s in your pantry: a new study suggests that older adults who eat the most ultra-processed foods — think sugar-sweetened drinks, deli meats, and fast food — may face a meaningfully higher risk of cognitive decline compared with those who favor whole, minimally processed foods.
In the study, published online June 3, 2026, by the American Journal of Public Health, Harvard researchers analyzed data from 5,370 older adults participating in the nationwide Health and Retirement Study, tracking them for nearly nine years between 2012 and 2020. Participants (average age 64, 55% women) completed dietary questionnaires at the start of the study, and underwent standardized memory and attention tests every two years to assess their cognitive health.
At the study’s end, the people who’d reported eating the most ultra-processed food had a 58% higher risk of developing dementia compared with those who ate the least. The highest consumers were also found to have a 46% higher risk of developing cognitive impairment without dementia (CIND)
The results also held positive news: people who ate the most whole, minimally processed foods showed the opposite pattern, with a 41% lower risk of developing dementia and a 24% lower risk of CIND compared with the people who ate the least
While the study doesn’t prove these dietary choices caused the differences in brain health, a growing body of evidence links ultra-processed foods to obesity, diabetes, hypertension, and high LDL (bad) cholesterol — all known risk factors for cognitive decline. The findings suggest that protecting brain health is one more reason to limit ultra-processed foods
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