How highly processed foods harm memory in the aging brain: Study in animals suggests omega-3 may reduce effects

A new study found that rats who were fed highly processed foods for four weeks had a strong inflammatory response. This was accompanied with behavioral signs of memory loss.
Research also showed that the supplementation of the processed diet with DHA, an omega-3 fatty acid, prevented memory problems in older rats and almost eliminated the inflammatory effects.

Young adult rats who ate processed food did not show cognitive problems or neuroinflammation.

The study diet replicated ready-to-eat foods such as potatoes chips, pizza, pasta, and frozen entrees.

High-processed diets are associated with obesity and type-2 diabetes. This suggests that older consumers may want to cut back on convenience foods and include foods high in DHA such as salmon to their diets. This is especially important considering the four week time span in which this study showed evidence of harm to the brains of the elderly.

"The fact that we're seeing these results so quickly is alarming," stated Ruth Barrientos (senior study author, Ohio State University Institute for Behavioral Medicine Research) and associate professor of psychiatry.


These findings show that consuming processed foods can cause memory loss. In an aging population, this is more likely to lead to neurodegenerative diseases like Alzheimer's. This awareness can help us to reduce the intake of processed foods and increase our intake of omega-3 fatty acids DHA, which could slow or stop the progression.

The journal Brain, Behavior, and Immunity published the research.

Barrientos' lab examines how everyday events, such as surgery, infection, or unhealthy eating habits, can trigger inflammation in the aged brain. The laboratory focuses on the amygdala and hippocampus regions. Her previous research has shown that a high-fat, short-term diet can cause memory loss and brain inflammation in older animals. DHA levels in the amygdala and hippocampus of the aged rats brain are also lower.

DHA (or docosahexaenoic Acid) is an omega-3 fatty oil that's found in fish and other seafood. DHA has multiple functions in the brain, including a role in fighting inflammation -- this is the first study to show that it can be used against brain inflammation caused by processed foods.

Randomly, the research team assigned male 3-month-old and 24-month old male rats to their normal diets (32% calories of protein, 54% from complex carbs made from wheat and 14% from oil), a high-processed diet (19.6% calories from protein and 63.3% refined carbs -- sucrose, cornstarch and maltodextrin -- and 17.1% fat) or the same processed diet with DHA.


The activation of genes that are associated with a powerful proinflammatory protein was significantly higher in the amygdala and hippocampus of older rats who ate processed food alone than it was in young rats who ate any other diet, and the same for aged rats who ate DHA-supplemented processed foods.

In behavioral experiments, the older rats with processed diet showed memory loss that was not evident in the younger rats. They also forgot to have spent time in unfamiliar spaces within a few days. This is a sign that the hippocampus has problems with context memory. Additionally, they did not exhibit anticipatory fear behavior in response to danger cues, which suggests abnormalities in their amygdala.

"The amygdala has been linked to memories that are associated with anxiety-producing and emotional fear in humans." Barrientos stated that if this area of the brain is not functioning properly, cues that warn of danger could be missed which could lead to poor decisions.

Also, the results showed that DHA supplementation to the processed-food diets of older rats prevented an elevated inflammatory response in their brains and behavioral signs of memory impairment.

Researchers are unable to determine the exact amount of DHA or the precise nutritional content of the animals' diets, as they had unlimited food access. Both age groups gained significant weight from processed food, with older animals gaining significantly more weight than younger animals. DHA supplementation did not prevent weight gain from high-processed foods.

This was the key finding. Barrientos warned against taking the results as a licence for consumers to eat processed foods, as long as they are taking a DHA supplement. She suggested that focusing on improving overall diet would be a better way to avoid multiple negative effects from highly refined foods.

These are diets advertised as low in fat but high in processed carbohydrates. She said that they lack fiber and contain refined carbohydrates, which are also known as low quality carbohydrates. "People who are used to looking at nutrition information should pay more attention to the quality and fiber of carbohydrates. These are very important points, as this study demonstrates.

The National Institute on Aging, National Institute of Dental and Craniofacial Research and Ohio Agricultural Research and Development Center supported this research. Christopher Butt, Inotiv Inc., Boulder, Colorado, and Stephanie Muscat are co-authors.