Does racial or ethnic discrimination influence your food choices? Well, yes! According to research discrimination exposure increases activation in the regions of the brain associated with reward and self-indulgence, hence seeking “feel-good” sensations and “comfort foods” – while decreasing self-control. According to research, in response to stressful discrimination experiences, one seeks comfort in food, manifested as increased cravings, and increased desire for highly palatable foods, such as high-calorie foods and, especially, sweet foods.
Individuals who experience racial or ethnic prejudice on a regular basis may be more vulnerable to obesity and associated health problems due in part to a stress response that alters bodily functions and our perception of food cues. These results come from a study conducted by researchers at UCLA that is thought to be the first to directly look at how discrimination affects how the brain-gut-microbiome (BGM) system influences reactions to different kinds of food.
The alterations seem to decrease activity in brain regions related to self-control and decision-making while increasing activation in areas linked to reward and self-indulgence, such as the pursuit of “comfort foods” and “feel-good” experiences.
Relationship between self-reported discrimination exposure and poor food choices?
“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,” said Arpana Gupta, PhD, a researcher and co-director of the UCLA Goodman-Luskin Microbiome Centre and the UCLA G. Oppenheimer Centre for Neurobiology of Stress and Resilience.
“Our results show that a person’s brain-gut crosstalk may change in response to ongoing experiences of discrimination — affecting food choices, cravings, brain function, and contributing to alterations in gut chemistry that have been implicated in stress and inflammation. It appears that in response to stressful discrimination experiences, we seek comfort in food, manifested as increased cravings, and increased desire for highly palatable foods, such as high-calorie foods and, especially, sweet foods. These alterations may ultimately cause people exposed to discrimination to be more vulnerable to obesity and obesity-related disorders,” said Gupta, senior author of the paper, which appears in Nature Mental Health.
Potential role of discrimination in obesity
Numerous factors, including genetics, nutrition, exercise, and others, have been the subject of previous research that has investigated why African Americans and other people from communities of colour have disproportionately high rates of obesity and related diseases. The putative involvement of discrimination in obesity has not received much attention in research, and this is the only study that we are aware of that directly links discrimination to eating habits through potential brain-gut interactions.
The results of functional MRI brain scans, advanced statistical modelling techniques, and analysis of the glutamate pathway’s metabolites in the digestive tract form the basis for the conclusions.
Discrimination-related differences in various food group categories
Participants filled out a validated and commonly used questionnaire measuring ongoing experiences of unfair treatment, comprising 107 individuals of various racial and ethnic backgrounds (20 men and 87 women). Based on their ratings, the participants’ responses were categorised into two groups: “high discrimination exposure” and “low discrimination exposure.”
Everyone gave a sample of their faeces. While MRI brain scans were being taken, they also finished a “food-cue” test that measured their brain responses to images of five distinct food types:
- Unhealthy, high-calorie, savoury.
- Unhealthy, high-calorie, sweet.
- Healthy, low-calorie, savoury.
- Healthy, low-calorie, sweet.
- Non-food — a control comparison consisting of pixelated images created from pictures of food.
The researchers examined responses to food cues in important brain areas to concentrate on discrimination-related differences in the various food group categories using these data.
Unhealthy food cues increased activation in brain areas linked to reward processing, motivation, appetite responses, and cravings in persons who reported more discriminatory encounters. These areas have been connected to the “feel-good” effects of eating particular foods.
When faced with food signals for harmful meals, stress from discriminatory experiences changes brain responses in brain regions related to self-regulation, but not for healthy foods.
Unhealthy sugary foods are important for the two-way exchange of information between the gut microbiota and the brain.
Discrimination exposure leads to higher levels of implicated inflammatory processes, oxidative stress
The researchers searched for alterations in 12 glutamate metabolites—substances that arise from the breakdown of glutamate—by analysing stool samples. Glutamate is a neurotransmitter that has been linked to ageing and a variety of stress responses. In this study, individuals in the greater discrimination group had higher levels of two glutamate metabolites that have been linked to oxidative stress, inflammatory processes, and an increased risk of obesity.
Discrimination exposure may lead to alterations in the bidirectional brain-gut microbiome communication
Considering both the current findings and other studies, the authors hypothesise that increased exposure to discrimination may cause changes in the two-way brain-gut microbiome communication that tilt human biology in favour of unhealthy eating habits and food cravings. This happens because of inflammatory processes in the gut-brain microbiome system that alter frontal-striatal circuits and cause dysregulations in glutamatergic signalling.
According to Gupta, the discoveries might aid scientists in creating therapies that target the gut or the brain.
“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,” she said. Gupta said the revelations may help researchers develop treatments that target the brain or the gut.
“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,” she said.
Materials provided by University of California – Los Angeles Health Sciences. Note: Content may be edited for style and length.
Xiaobei Zhang, Hao Wang, Lisa A. Kilpatrick, Tien S. Dong, Gilbert C. Gee, Jennifer S. Labus, Vadim Osadchiy, Hiram Beltran-Sanchez, May C. Wang, Allison Vaughan, Arpana Gupta. Discrimination exposure impacts unhealthy processing of food cues: crosstalk between the brain and gut. Nature Mental Health, 2023; DOI: 10.1038/s44220-023-00134-9
University of California – Los Angeles Health Sciences. “Discrimination alters brain-gut ‘crosstalk,’ prompting poor food choices and increased health risks.” ScienceDaily. ScienceDaily, 2 October 2023. <www.sciencedaily.com/releases/2023/10/231002124234.htm>.
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