Until only recently, it may have seemed silly to say the bacteria in your digestive tract can somehow “talk” to your brain, but more and more scientists are finding evidence of such a relationship. They call it the gut-brain connection, and last month researchers at Oregon State University revealed how a poor diet can impact that connection and lead to a decline in healthy brain function.
The standard American diet (or SAD) includes high amounts of sugar and unhealthy fats, which OSU scientists say may affect our ability to process and remember information. Specifically, a high-sugar, high-fat diet impacts something called “cognitive flexibility,” which allows us to think about more than one idea at a time. Too much fat and sugar also leads to problems with memory, say researchers.
The study involved young, healthy male mice who were fed one of three different diets: a high-sugar diet, a high-fat diet, or a normal diet. Fecal samples were taken before and after to monitor the bacterial environment in the gut, and both groups underwent testing to assess physical and mental function.
Looking at the results, the research team discovered a sharp decline in mental and physical ability for those mice on the high-sugar and high-fat diets when compared with those on a normal diet. Cognitive flexibility was decreased with both groups, and those on the high-sugar diet experienced significant memory impairment. Interestingly, the fecal samples of both groups showed lower numbers of beneficial bacteria and higher numbers of harmful bacteria in the gut.
“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.” said lead author Dr. Kathy Magnusson. “It’s not just the food that could be influencing your brain, but an interaction between the food and microbial changes.” Previous studies have found that similar changes in gut bacteria due to diet may trigger an unhealthy immune response in the body and promote inflammation.