diet high in processed foods leads to neuroinflammation and memory
decline in older rats, a new study reports. Supplementing a processed
food diet with DHA, an omega 3 fatty acid, helped mitigate memory
problems and reduce inflammation.
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.
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.
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
processed diets are also associated with obesity and type 2 diabetes,
suggesting older consumers might want to scale back on convenience foods
and add foods rich in DHA, such as salmon, to their diets, researchers
say – especially considering harm to the aged brain in this study was
evident in only four weeks.
fact we’re seeing these effects so quickly is a little bit alarming,”
said senior study author Ruth Barrientos, an investigator in The Ohio
State University Institute for Behavioral Medicine Research and
associate professor of psychiatry and behavioral health.
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.”
The research is published in the journal Brain, Behavior, and Immunity.
lab studies how everyday life events – such as surgery, an infection
or, in this case, an unhealthy diet – might trigger inflammation in the
aging brain, with a specific focus on the hippocampus and amygdala
regions. This work builds on her previous research suggesting a
short-term, high-fat diet can lead to memory loss and brain inflammation
in older animals, and that DHA levels are lower in the hippocampus and
amygdala of the aged rat brain.
or docosahexaenoic acid, is an omega-3 fatty acid that is present along
with eicosapentaenoic acid (EPA) in fish and other seafood. Among DHA’s
multiple functions in the brain is a role in fending off an
inflammatory response – this is the first study of its ability to act
against brain inflammation brought on by a processed diet.
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.
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.
older rats on the processed diet also showed signs of memory loss in
behavioral experiments that weren’t 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.
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,” Barrientos said.
results also showed that 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
don’t know the exact dosage of DHA – or precise calories and nutrients –
taken in by the animals, which all had unlimited access to food. Both
age groups gained a significant amount of weight on the processed diet,
with old animals gaining significantly more than the young animals. DHA
supplementation had no preventive effect on weight gain associated with
eating highly processed foods.
was a key finding: Barrientos cautioned against interpreting the
results as a license for consumers to feast on processed foods as long
as they take a DHA supplement. A better bet to prevent multiple negative
effects of highly refined foods would be focusing on overall diet
improvement, she said.
are the types of diets that are advertised as being low in fat, but
they’re highly processed. They have no fiber and have refined
carbohydrates that are also known as low-quality carbohydrates,” she
said. “Folks who are used to looking at nutritional information need to
pay attention to the fiber and quality of carbohydrates. This study
really shows those things are important.”
research was supported by the National Institute on Aging, the National
Institute of Dental and Craniofacial Research, and the Ohio
Agricultural Research and Development Center. Co-authors include Michael
Butler, Nicholas Deems, Stephanie Muscat and Martha Belury from Ohio
State and Christopher Butt of Inotiv Inc. in Boulder, Colorado.