The gut microbiota is made up of a variety of microorganisms, including bacteria, fungi, archaea, and viruses, that live in the digestive tract. These microorganisms work together, affecting not only physical functions but cognitive processes. Known as the “gut-brain axis,” this interaction can also have important implications for mental health and disorders like depression, anxiety, autism, and addiction, and substance use disorders (SUDs) particularly if the microbiota isn’t functioning as it should. Alcohol abuse, for example, reduces helpful bacteria in the gut, increases gut permeability, and leads to inflammatory factors, ultimately contributing to alcoholism. Similarly, other substance use disorders, like opioid, cocaine, and methamphetamine addictions, are linked to changes in the microbiota.While still not recognized in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), food addiction is gaining attention as a complex behavioral disorder, particularly as the obesity crisis remains ongoing and cases of type 2 diabetes are becoming more prevalent. This form of addiction involves compulsive eating of usually not-so-healthy foods, which causes changes in the brain’s reward system that trigger the need to keep eating despite internal cues signaling fullness. The Yale Food Addiction Scale (YFAS) 2.0, has been used to evaluate food addiction based on criteria similar to those for SUDs, such compulsive eating and reoccurring food seeking.In a new study published in the journal Gut, researchers first identified different gut microbiota patterns in food-addicted mice compared to those not addicted, using the YFAS 2.0 criteria to separate the two in each categories and assess potential gut microbiota markers for food addiction. They then compared these to humans, discovering that the bacteria genus Blautia was notably different in both addicted mice and humans. By giving the mice non-digestible carbohydrates like lactulose and rhamnose to increase Blautia levels, researchers prevented food addiction. Similarly, giving Blautia wexlerae, a beneficial microbe, showed the same results. This suggests that altering gut microbiota with dietary supplements or beneficial microbes can help curb addiction.

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The addicted mice also showed higher persistence, motivation, and compulsivity to eat compared to non-addicted mice, despite similar food intake and body weight. Certain bacteria, like Ruminococcaceae and Clostridiales, were linked to motivation and persistence, suggesting possible targets for addiction treatment.Overall, the team reported the following key findings:Enterorhabdus (Actinobacteria phylum): Increased in non-addicted mice, potentially beneficial for psychiatric disorders. Negative correlations with brain kynurenine levels suggest a link to improved mental health.Lachnospiraceae (Bacillota/Firmicutes phylum): Shows potential protective effects in food addiction, although results vary with species.Allobaculum (Bacillota/Firmicutes phylum): Indicated as protective in food addiction, correlating with positive outcomes in models of obesity and alcohol addiction.Blautia (Lachnospiraceae family): Downregulated in addicted mice; suggested beneficial effects on brain function and food addiction.Anaeroplasma (Tenericutes phylum): Increased in addicted mice, linked to negative effects such as obesity.Gastranaerophilales: Associated with the addiction-like criterion of motivation, implying non-beneficial effects.The study applied the YFAS 2.0 criteria to both mice and humans, finding similar gut microbiota patterns linked to food addiction. However, the team acknowledged the need to conduct further studies involving humans to confirm their findings. For now, identifying non-beneficial bacteria as biomarkers for food addiction could help to predict biological vulnerabilities to compulsive overeating and food seeking so proactive measures can be taken to curb potential addiction and, perhaps, reduce climbing obesity and type 2 diabetes rates.

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Gut microbiota signatures of vulnerability to food addiction in mice and humansStudy finds specific gut microbiota signature is associated with vulnerability to food addiction