Because stress alters biological processes and how we interpret food signals, scientists say those who experience racial or ethnic prejudice regularly may be more prone to obesity and related health problems.
The study dove into the impact of discrimination and how these reactions influence the brain-gut-microbiome (BGM) system.
The findings, conducted by UCLA, say modifications appear to decrease activity in brain sections related to decision-making and self-control while increasing activation in brain areas related to reward and self-indulgence, such as seeking "feel-good" from "comfort foods."
According to Arpana Gupta, a researcher, and co-director of the UCLA Goodman-Luskin Microbiome Center and the UCLA G. Oppenheimer Center for Neurobiology of Stress and Resilience, the findings demonstrate how a person's brain-gut crosstalk may evolve in response to persistent experiences of discrimination, impacting appetites, dietary preferences, and brain function and causing changes in gut chemistry that have been linked to stress and inflammation.
"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 manifested as alterations in the bidirectional communication between the brain and the gut microbiome."- Gupta
People's increased appetites and desire for certain meals, such as high-calorie and junk foods, seem to respond to stressful situations involving prejudice. These changes may ultimately make those who have experienced discrimination more susceptible to obesity and fat-related illnesses.
Numerous variables, including genetics, nutrition, exercise, and others, have been examined in earlier research to explain why African Americans and other people of color have disproportionately high rates of obesity and associated diseases.
The results of functional MRI brain scans, advanced statistical modeling methods, and investigations of metabolites produced by the glutamate pathway in the digestive system served as the foundation for the conclusions.
How did UCLA direct the study?
One hundred seven participants, 87 women and 20 men, from various racial and ethnic origins, participated in the study. They answered a validated and frequently used questionnaire that assesses persistent experiences of unjust treatment.
Participants' replies were split into groups with "high discrimination exposure" and "low discrimination exposure," according to their scores.
The findings demonstrated that unhealthy food signals increased brain activity related to reward processing, motivation, cravings, and hunger responses among those with more discriminatory encounters. These areas have been associated with the "feel-good" effects of ingesting particular foods.
The findings also showed that when exposed to food signals for unhealthy meals but not for healthy foods, stress from discriminating experiences affected brain responses in areas linked with self-regulation.
In this study, participants in the greater discrimination group had higher levels of two glutamate metabolites that have been linked to inflammation, oxidative stress, and an increased risk of obesity.
According to the scientists, considering the current findings and earlier studies, more exposure to discrimination may cause changes in the bidirectional brain-gut microbiome communication that tilts our biology toward unhealthy eating habits and desires for unhealthy foods.
This happens due to inflammatory processes in the brain-gut microbiome system. According to Gupta, the information may aid in developing therapies focusing on the stomach or the brain.
She concludes: "At the brain level, treatments could be developed to modulate the food-related reward system or the hyper-aroused brain circuits associated with stress and discrimination exposure. On the other end of the spectrum, at the gut level, it also means we can target the glutamatergic pathways – possibly with probiotic supplementation or anti-inflammatory dietary changes – as a therapeutic approach to treat stress-related experiences such as discrimination."
- Nature Mental Health. Discrimination exposure impacts unhealthy processing of food cues: crosstalk between the brain and gut.
- BMJ. Role of the gut microbiota in nutrition and health.
- Nature Reviews Microbiology. The gut microbiota–brain axis in behaviour and brain disorders.