Discrimination Affects Brain Gut Link to Increase Obesity Risk – Pas Trusted News

A new study looks at how racial and ethnic discrimination can affect the gut. nazar_ab/Getty Images
  • Racial discrimination increases the risk of poorer mental health, sleep problems, inflammation and obesity — in adults and children.
  • The link between racial discrimination and obesity may be due to a stress-related disruption of the communication between the brain and gut microbiome.
  • Coping strategies can help people reduce the impact of racial discrimination on their health, but policy changes are needed to reduce people’s exposure to discrimination.

People who experience frequent racial or ethnic discrimination are more susceptible to obesity and related conditions, with some research showing that these higher risks begin to appear in childhood.

Obesity is a major public health issue in the United States, affecting more than four in 10 American adults, according to the Centers for Disease Control and Prevention (CDC). Black and Hispanic adults face even higher rates of obesity.

Similar patterns are seen in children and teens, with Black and Hispanic youth more likely to be affected by obesity than white youth, CDC data shows. Overall, one in five American youth have obesity.

Some research shows that higher rates of obesity among certain racial and ethnic groups may stem from factors such as genetics; individual physical activity levels; access to healthy, affordable foods; and exposure to unhealthy food product marketing.

Other research has focused on another known stressor — racial or ethnic discrimination — which increases the risk of poorer mental health, sleep problems, and physical issues such as cardiovascular disease and inflammation.

Discrimination has also been linked to higher body mass index (BMI), waist circumference and rates of obesity — in adults and youth.

A new study suggests that this link to obesity may be partly due to stressful discrimination changing how people’s brains process food cues and disrupting communication between the gut microbiome and the brain.

The gut microbiome, which consists of bacteria and other microbes living in the intestines, plays a role in health and disease, including mental health and may also influence behavior.

“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,” Arpana Gupta, PhD, a researcher and co-director of the UCLA Goodman-Luskin Microbiome Center and the UCLA G. Oppenheimer Center for Neurobiology of Stress and Resilience, said in a news release.

The study, published Oct. 2 in Nature Mental Health, included 107 people — 87 women and 20 men — of diverse racial and ethnic backgrounds.

Participants completed a questionnaire that measures chronic experiences of unfair treatment. Based on their responses, researchers divided people into “high discrimination exposure” and “low discrimination exposure” groups.

People had MRI brain scans while completing a “food-cue task” involving looking at pictures of four different types of food — two healthy and two unhealthy — and one non-food picture as a comparison.

In addition, people provided a stool sample, which researchers used to measure changes in the levels of 12 glutamate metabolites, or breakdown products.

Glutamate is a neurotransmitter that is linked with inflammation related to conditions such as anxiety and depression. Research also shows that glutamate is involved in the brain’s reward system and related behaviors like impulsivity.

In the study, people who reported greater levels of discrimination had higher levels of two glutamate breakdown products associated with inflammation, oxidative stress and an increased risk of obesity, researchers found.

People who reported more experiences of discrimination also had greater activation in certain areas of the brain in response to unhealthy food cues. The activated regions are involved in reward processing, motivation, cravings and appetite responses.

Discrimination-related stress was also associated with changes in brain responses involved in self-regulation — this occurred only with cues for unhealthy foods, not for healthy foods.

In addition, unhealthy sweet food was involved in changing the two-way communication between the brain and the gut microbiome, the results showed.

Researchers say that the new study and earlier research suggest that racial or ethnic discrimination may lead to changes in communication between the brain and gut microbiome, which shifts people toward unhealthy eating behaviors.

“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,” Gupta said in the release.

“These alterations may ultimately cause people exposed to discrimination to be more vulnerable to obesity and obesity-related disorders,” she added.

Rebecca Hasson, PhD, associate professor of movement science and director of the Childhood Disparities Research Laboratory at the University of Michigan School of Kinesiology, emphasized that discrimination is one particular form of toxic stress, one that is known to have negative health effects.

Discrimination also comes in many forms, including that based on race or ethnicity, weight, gender or other social identity.

“So when you look at discrimination, you’re now talking about a specific toxic stressor that can cause both psychological and physiological changes in the human body which leads to a whole host of diseases,” she told Healthline.

Studies like the new one, which focus on racial discrimination, “provide more evidence that this is a serious stressor that we need to pay attention to,” she said.

In a paper published this month in Psychosomatic Medicine, she and her colleagues found that teens who experienced racial discrimination from other teens — peer discrimination — had unhealthy levels of the stress hormone cortisol throughout the day.

Disruptions in cortisol levels and patterns are connected to chronic health conditions such as depression, fatigue and cardiovascular disease.

Adolfo Cuevas, PhD, assistant professor of social and behavioral sciences at the NYU School of Global Public Health, said the new study also provides some understanding of what connects experiences of discrimination to obesity.

“Studies [such as this] are showing us that discrimination has a real impact on our physiology and increases the risk of disease,” he told Healthline. “In other words, this is not simply happening in someone’s head.”

“In fact, these experiences are embodied, and are contributing to poor health outcomes and short life expectancy for a large group of Americans in the United States,” he said.

Research by Cuevas and his colleagues found that greater racial discrimination in children and adolescents is associated with higher BMI and waist circumference.

While the results, published earlier this year in JAMA Network Open, showed that the effect of discrimination was small, Cuevas pointed out that the study looked at only a snapshot of these children’s lives.

“These experiences of discrimination are not just happening one time,” he said. “This is happening over and over, at a critical period in these kids’ lives.”

The effects of discrimination accumulate as children move into adulthood, which Cuevas said has huge implications for public health. So “we have to find psychological and social resources to help mitigate that,” he said.

This might include “finding ways for clinicians, teachers, principals and even children to work together to create a greater appreciation of different cultures within the school system,” he added, “in order to reduce exposure to discrimination.”

Hasson said children, teens and adults don’t have to be exposed to a lot of racial discrimination to be negatively impacted by it.

“So we need to be paying attention to it, in terms of how do we help people build resilience or develop coping strategies?” she said.

Some research suggests that exercise may help buffer the stress response, she said, which means having a smaller cortisol response when you encounter a stressor.

Exercise may also act as a coping mechanism, she added, helping people distract themselves from an experience of discrimination or rebalance their system.

Physical activity can also build social relationships and support networks.

“A great example of this is GirlTrek, an organization that is using physical activity to help African American women cope with race-related stressors,” said Hasson.“

Gupta said in the release that the results of the new study may help researchers develop treatments that target the brain or gut in order to reduce the effects of stress and discrimination.

This might involve taking a probiotic supplement or making changes to the diet to reduce inflammation associated with discrimination.

However, Cuevas cautions that the burden for reducing the impacts of these stressors should not fall on the victims of discrimination.

“We should begin thinking about ways that we can change social structures to reduce children’s exposure to discrimination and also the risk of obesity,” he said.

Hasson agrees that while it’s important to help individuals learn coping mechanisms for dealing with stressors, she emphasized that policy solutions are needed to eliminate exposure to these stressors in the first place.

For example, “how do we create safe environments, through policy, to promote positive relationships that help people see the humanity of every individual?” she said.

This approach is not just important to those most affected by racial discrimination but to everyone.

“While communities of color experience racial discrimination at a much higher rate, it is important to know that this is a universal problem,” said Hasson. “So we need to find a universal solution to help all communities combat the negative effects of racism.”

Black and Hispanic youth and adults are at higher risk of obesity. A new study suggests that racial discrimination may contribute to this health disparity by disrupting the communication between the brain and the gut microbiome.

People who reported higher exposure to racial discrimination had greater activation in certain areas of the brain in response to pictures of unhealthy foods. They also had a decrease in activity in areas of the brain involved in self-regulation, but only for unhealthy food cues.

Exercise programs and other interventions may help people cope with racial discrimination and reduce the negative health effects. But experts say policy changes are needed to reduce people’s exposure to discrimination in the first place.

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