UCLA GOODMAN-LUSKIN MICROBIOME CENTER
Experiencing Discrimination May Cause Biological Changes That Promote Unhealthy Eating Behaviors, Study Finds
“We examined complex relationships between self-reported discrimination exposure and poor food choices, and we can see these processes lead to increased cravings for unhealthy foods, especially sweet foods, but also manifest as alterations in the bidirectional communication between the brain and the gut microbiome,” says Dr. Gupta, the study’s senior author. “Our results show that a person’s brain-gut crosstalk may change in response to ongoing experiences of discrimination — affecting food choices, cravings, and brain function, and contributing to alterations in gut chemistry that have been implicated in stress and inflammation.” The UCLA team analyzed the brain activity and gut compounds of 107 participants from diverse racial and ethnic backgrounds who completed a validated and widely used questionnaire measuring chronic experiences of unfair treatment. Based on their scores, participants were divided into “high discrimination exposure” and “low discrimination exposure” groups. MRI scans were used to evaluate brain responses to pictures of high-calorie sugary and fatty foods, as well as healthier, low-sugar and low-fat foods. For participants in the high-discrimination exposure group, unhealthy food cues caused greater activation in regions of the brain associated with reward processing, motivation, cravings, and appetite responses. The study found that stress from discrimination experiences altered brain responses in regions involved with self-regulation in response to food cues for unhealthy foods, but not for healthy foods. Fecal samples were also provided to allow the researchers to study participants’ gut microbiome — specifically, changes in 12 glutamate metabolites. Participants in the high- discrimination group showed elevated levels of two glutamate metabolites that have been implicated in inflammatory processes, oxidative stress, and increased risk for developing obesity. “It appears that in response to stressful discrimination experiences, we seek comfort in food, and increased desire for highly palatable foods such as high-calorie foods and, especially, sweet foods,” Dr. Gupta says of the study findings. “These alterations may ultimately cause people exposed to discrimination to be more vulnerable to obesity and obesity- related disorders.” The study’s findings have the potential to assist researchers in developing treatments that target the brain or gut — either by modulating brain changes associated with stress and discrimination exposure, or by targeting the glutamatergic pathways.
Arpana Gupta, PhD
Experiencing racial or ethnic discrimination can increase a person’s risk of obesity through a stress response that disrupts brain-gut communication — changing biological processes in how they process food cues and thereby promoting unhealthy eating behaviors, according to a study led by a member of the Vatche and Tamar Manoukian Division of Digestive Diseases faculty. These changes appear to increase activation in regions of the brain associated with reward and self-indulgence, which could make individuals exposed to high levels of discrimination more likely to be drawn to “comfort foods” high in sugar and fat, according to the UCLA research team, which was led by Arpana “Annie” Gupta, PhD, co-director of the Goodman-Luskin Microbiome Center and a member of the G. Oppenheimer Center for Neurobiology of Stress and Resilience. The study, published in Nature Mental Health , also found that these individuals showed decreased activity in brain areas involved in decision-making and self-control. The findings are based on results of functional MRI brain scans, sophisticated statistical modeling techniques, and analyses of metabolites of the glutamate pathway in the digestive tract. Racial and ethnic groups that face significant levels of discrimination in the U.S. have higher rates of obesity and the health conditions associated with it, but the factors contributing to these disparities haven’t been clear. While previous research has examined issues including genetics, diet, and exercise, few studies have addressed the potential role of discrimination, and this is believed to be the first study providing direct evidence of a possible link between brain-gut interactions and obesity-promoting eating behaviors.
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Beyond the Scope
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