If you love your fried, fatty foods smothered in chocolate and generously dusted with icing sugar? Then, you might just have to say goodbye to mental acuity.
A new research conducted in Oregon State University has revealed that a high-sugar, high-fat diet can drastically modify your gut bacteria which in turn may lead to significant losses in ‘cognitive flexibility’ – a measurement of the brain’s ability to switch between thinking about one concept to another, and to adapt to changes in the environment.
The study, which was conducted on mice and published this week in the journal Neuroscience, showed that a high-sugar diet was detrimental to brain function, leading not only to decreased cognitive flexibility but also to impairments in both short- and long-term memory – thereby increasing your chances of dementia later in life.
“We’ve known for a while that too much fat and sugar are not good for you,” Dr. Kathy Magnusson, a biomedical scientist at the university and the study’s lead author, said in a statement. “This work suggests that fat and sugar are altering your healthy bacterial systems, and that’s one of the reasons those foods aren’t good for you. It’s not just the food that could be influencing your brain, but an interaction between the food and microbial changes.”
For the study, the researchers fed groups of mice a high-fat diet, a high-sugar diet or a normal diet, and gave them tests measuring various physical and mental functions. To analyzechanges to the gut microbiome — the community of trillions of bacteria living in the gut — the researchers also analyzed fecal samples prior to the implementation of the diet and again five weeks after adopting the diet.
What did they find? After just four weeks on the high-fat or high-sugar diet, the mice performed worse on a series of mental and physical tests, compared to the mice on a normal diet. The mice on both diets performed particularly poorly on the test of cognitive flexibility, in which they were expected to find a new escape route from their cages.
As Magnusson suggests, the findings aren’t very shocking. They’re the latest to join a growing body of research that has shown that the trillions of bacteria living in the gut can have a major influence on brain function and mental health. The upshot? Diet could play an important role in neurological and mental health, both for better and for worse.
The microbiome analysis revealed that higher percentages of “bad” gut bacteria and lower amounts of healthy bacteria among the high-sugar and high-fat groups were directly correlated with worse performance on the tests of cognitive flexibility.
In humans, poor cognitive flexibility can manifest in difficulty understanding new concepts or adapting to new experiences.
“Think about driving home on a route that’s very familiar to you, something you’re used to doing,” Magnussion explained in a statement. “Then one day that road is closed and you suddenly have to find a new way home.”A person with high levels of cognitive flexibility would be quick to find an alternative route, while someone with lower cognitive flexibility would be more likely to struggle to find a new way home.
“There’s also evidence that the bacteria can release chemicals that are used as transmitters in the brain,” Magnusson said in an email to The Huffington Post. “So they’re producing things like serotonin, and we have receptors in our brain that will react to serotonin.”
The mounting evidence has even led some scientists to refer to Alzheimer’s disease as “Type 3 diabetes,” because of the association with chronically elevated blood sugar levels and insulin resistance with cognitive decline.
“Artificial sweeteners are likely even worse [than sugar] because they have a huge effect on changing the microbiome,” neurologist Dr. David Perlmutter, author of Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain for Life, told The Huffington Post. “Your risk of diabetes is twice as great if you’re consuming diet drinks, which is far greater than if you’re drinking sugar-sweetened beverages.”
However, there is always good news! If you want a healthy brain then a balanced diet that’s relatively low in sugar, artificial sweeteners and unhealthy fats — and high in probiotics, the “good” bacteria that support digestion, immune health and even mental health — can support the health of both the gut and the brain.
“A brain-healthy diet is one that’s very low in sugar and carbohydrates that welcomes fat back to the table, but only good fat — not trans fats, not the modified fats,” said Perlmutter. “It’s mostly vegetables on the plate — colorful, nutrient-dense vegetables that are rich in fiber.”