A recent study has discovered that feeding animals a diet high in saturated fat for nine weeks causes changes in their gut bacteria that impact brain chemicals and contribute to anxiety. Researchers at the University of Colorado Boulder found that a high-fat diet disrupts gut bacteria, changes behavior, and affects brain chemicals through a complex pathway linking the gut to the brain, which can lead to anxiety. It’s well known that unhealthy foods such as these can have negative effects on the body.”Usually, we only think about the impact of high-fat diets in terms of weight gain,” explained Christopher Lowry, a professor of integrative physiology at CU Boulder. “But if we understand that they can also affect the brain and potentially cause anxiety, then the stakes are even higher.”
Lowry’s research team conducted an experiment with adolescent rats, splitting them into two groups. One group was fed a standard diet consisting of about 11% fat for nine weeks, while the other group was fed a high-fat diet of 45% fat, mainly from saturated fat found in animal products.
The typical American diet contains approximately 36% fat, as reported by the Centers for Disease Control and Prevention.
Throughout the study, The researchers examined fecal samples and evaluated the microbiome of the animals, which refers to the gut bacteria. After nine weeks, the animals were subjected to behavioral tests.
When compared to the control group, the group that consumed a high-fat diet showed expected weight gain. However, they also displayed significantly lower diversity of gut bacteria. Lowry noted that greater bacterial diversity is generally linked to better health. Additionally, they had a higher level of Firmicutes and a lower level of Bacteroidetes. A higher ratio of Firmicutes to Bacteroidetes has been connected to the typical diet of industrialized societies.The group of rats on a high-fat diet also displayed increased activity of three genes (tph2, htr1a, and slc6a4) involved in the creation and transmission of the neurotransmitter serotonin, particularly in a part of the brainstem called the dorsal raphe nucleus (DRN), which is connected to stress and anxiety. While serotonin is often referred to as a “feel-good brain chemical,” Lowry points out that specific serotonin neurons can actually trigger anxiety-like responses in animals when activated. The increased activity of tph2, also known as tryptophan hydroxylase, in the DRN has been linked to changes in mood.disorders and suicide risk in humans.
“It is remarkable to consider that a high-fat diet alone could change the expression of these genes in the brain,” Lowry stated. “The high-fat group essentially displayed the molecular pattern of heightened anxiety in their brain.”
Lowry suspects that an unhealthy microbiome weakens the gut lining, allowing bacteria to enter the body’s circulation and communicate with the brain through the vagus nerve, a pathway from the gastrointestinal tract to the brain.
“If you consider human evolution, it is logical,” Lowry noted. ”We are instinctively wired to pay attention to things that make us ill so we can survive.”
Avoiding these things in the future is important.”
Lowry emphasizes that not all fats are negative, and that beneficial fats like those found in fish, olive oil, nuts and seeds can have anti-inflammatory properties and be beneficial for the brain.
His recommendation: Consume a wide variety of fruits and vegetables, incorporate fermented foods into your diet to support a healthy microbiome, and reduce consumption of pizza and fries. Additionally, when eating a hamburger, consider adding a slice of avocado. Some studies indicate that good fats can counteract some of the negative effects.
