Highly processed foods are filled with questionable synthetic and industrialized additives that have been linked in scientific studies with a variety of serious health problems. Now new scientific research results indicate that eating a diet of highly processed foods may be harmful to memory–especially as we age. Just four weeks on a diet of highly processed food led to a strong inflammatory response in the brains of aging rats that was accompanied by behavioral signs of memory loss, the new study has found.
The research team randomly assigned 3-month-old and 24-month-old male rats to their normal chow (32% calories from protein, 54% from wheat-based complex carbs and 14% from fat), a highly processed diet (19.6% of calories from protein, 63.3% from refined carbs — cornstarch, maltodextrin and sucrose — and 17.1% from fat), or the same processed diet supplemented with DHA.
The study diet mimicked ready-to-eat human foods that are often packaged for long shelf lives, such as potato chips and other snacks, frozen entrees like pasta dishes and pizzas, and deli meats containing preservatives.
Activation of genes linked to a powerful pro-inflammatory protein and other markers of inflammation was significantly elevated in the hippocampus and amygdala* of the older rats that ate the processed diet alone compared to young rats on any diet and aged rats that ate the DHA-supplemented processed food.
The older rats on the processed diet also showed signs of memory loss in behavioral experiments that were not evident in the young rats. They forgot having spent time in an unfamiliar space within a few days, a sign of problems with contextual memory in the hippocampus, and did not display anticipatory fear behavior to a danger cue, which suggested there were abnormalities in the amygdala.
*The amygdala in humans has been implicated in memories associated with emotional — fear and anxiety-producing — events. If this region of the brain is dysfunctional, cues that predict danger may be missed and could lead to bad decisions.
The new study found that just four weeks on a diet of highly processed food led to a strong inflammatory response in the brains of aging rats that was accompanied by behavioral signs of memory loss. Researchers also found that supplementing the processed diet with the omega-3 fatty acid DHA prevented memory problems and reduced the inflammatory effects almost entirely in older rats. Neuroinflammation and cognitive problems were not detected in young adult rats that ate the processed diet.
“These findings indicate that consumption of a processed diet can produce significant and abrupt memory deficits — and in the aging population, rapid memory decline has a greater likelihood of progressing into neurodegenerative diseases such as Alzheimer’s disease. By being aware of this, maybe we can limit processed foods in our diets and increase consumption of foods that are rich in the omega-3 fatty acid DHA to either prevent or slow that progression.”
-Dr. Ruth Barrientos, investigator in The Ohio State University Institute for Behavioral Medicine Research and associate professor of psychiatry and behavioral health
Journal Reference: Michael J. Butler, Nicholas P. Deems, Stephanie Muscat, Christopher M. Butt, Martha A. Belury, Ruth M. Barrientos. Dietary DHA prevents cognitive impairment and inflammatory gene expression in aged male rats fed a diet enriched with refined carbohydrates. Brain, Behavior, and Immunity, 2021; 98: 198 DOI: 10.1016/j.bbi.2021.08.214