A four-week diet of highly processed foods caused a strong inflammatory response in the brains of aging rats, which was accompanied by behavioral signs of memory loss, according to a new study. In addition, researchers discovered that supplementing the processed diet with the omega-3 fatty acid DHA prevented memory problems and almost entirely reduced the inflammatory effects in older rats.
In addition, researchers discovered that supplementing the processed diet with the omega-3 fatty acid DHA prevented memory problems and almost entirely reduced the inflammatory effects in older rats. In young adult rats fed the processed diet, there was no evidence of neuroinflammation or cognitive problems.
The study diet consisted of ready-to-eat human foods that are frequently packaged for long shelf lives, such as potato chips and other snacks, frozen entrees such as pasta dishes and pizzas, and preservative-laden deli meats.
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, a new study has found.
Highly processed diets are also associated with obesity and type 2 diabetes, researchers say, implying that older consumers should cut back on convenience foods and add foods high in DHA, such as salmon, to their diets, especially given that the harm to the aged brain in this study was evident after only four weeks.
“The fact that we’re seeing these effects so quickly is a little concerning,” said senior study author Ruth Barrientos, an investigator at The Ohio State University Institute for Behavioral Medicine Research and an associate professor of psychiatry and behavioral health.
“These findings suggest that eating a processed diet can cause significant and abrupt memory deficits – and in the aging population, rapid memory decline is more likely to progress to neurodegenerative diseases like Alzheimer’s. By being aware of this, we may be able to limit our consumption of processed foods and increase our consumption of foods high in the omega-3 fatty acid DHA, thereby preventing or slowing the progression.”
The findings have been published in the journal Brain, Behavior, and Immunity.
Barrientos’ lab investigates how common life events, such as surgery, infection, or, in this case, an unhealthy diet, can cause inflammation in the aging brain, with a particular emphasis on the hippocampus and amygdala regions. This study adds to her previous findings that a high-fat diet for a short period of time can cause memory loss and brain inflammation in older animals and that DHA levels are lower in the hippocampus and amygdala of the aged rat brain.
DHA, or docosahexaenoic acid, is an omega-3 fatty acid found in fish and other seafood, along with eicosapentaenoic acid (EPA). Among DHA’s many functions in the brain is its ability to prevent inflammatory responses; this is the first study of its ability to prevent brain inflammation caused by a processed diet.
The researchers randomly assigned 3-month-old and 24-month-old male rats to their normal chow (32 percent protein, 54 percent complex carbs from wheat, and 14 percent fat), a highly-processed diet (19.6 percent protein, 63.3 percent refined carbs from cornstarch, maltodextrin, and sucrose, and 17.1 percent fat), or the same processed diet supplemented with DHA.
In the hippocampus and amygdala of older rats that ate the processed diet alone, activation of genes linked to a powerful pro-inflammatory protein and other markers of inflammation was significantly higher than in young rats on any diet and aged rats that ate the DHA-supplemented processed food.
In behavioral experiments, the older rats on the processed diet also showed signs of memory loss that were not seen in the young rats. They forgot they had spent time in an unfamiliar space within a few days, indicating problems with contextual memory in the hippocampus, and they did not exhibit anticipatory fear behavior in response to a danger cue, indicating amygdala abnormalities.
“In humans, the amygdala has been linked to memories of emotional (fear and anxiety-inducing) events. If this part of the brain is dysfunctional, cues that indicate danger may be missed, leading to poor decisions “According to Barrientos.
DHA supplementation of the processed-food diets consumed by the older rats effectively prevented the elevated inflammatory response in the brain as well as behavioral signs of memory loss, according to the findings.
Researchers don’t know the exact amount of DHA ingested by the animals, or the exact calories and nutrients they consumed, despite the fact that all of them had unlimited access to food. On the processed diet, both age groups gained significant amounts of weight, with older animals gaining significantly more than younger animals. DHA supplementation had no effect on weight gain caused by eating highly processed foods.
That was a significant finding, and Barrientos cautioned against interpreting the findings as a green light for consumers to consume processed foods as long as they took a DHA supplement. She believes that focusing on overall diet improvement would be a better bet for preventing the multiple negative effects of highly refined foods.
“These are the low-fat diets that are widely advertised, but they are highly processed. They lack fiber and contain refined carbohydrates, also known as low-quality carbohydrates “She stated. “People who are used to looking at nutritional information should pay attention to fiber and carbohydrate quality. This study demonstrates the significance of those factors.”