The wrong mix of bacteria can promote a feeding frenzy, but the right balance will protect you.
It’s a little creepy how many of our behaviours may be due to choices made by our guts, rather than our brains.
The symbiotic relationship between gut microbiota and their hosts is now well known to affect both physical and mental processes, and has already been implicated in alcohol and cocaine abuse.
Now food addiction looks like it could come down to having too much of one kind of bacteria in your gut and not enough of another.
Researchers presenting at the Federation of European Neuroscience Societies (FENS) Forum 2024 in Vienna last month explained how the gut microbiome of both mice and humans with extreme food addiction contained bacteria belonging to the Proteobacteria phylum and had a dearth of bacteria belonging to the Actinobacteria phylum and Blautia from the Bacillota phylum.
When the mice in their study were given prebiotics to increase the presence of Blautia in the gut, there were “dramatic improvements” in their food addiction behaviour, presenter Professor Elena Martín-García, from Universitat Pompeu Fabra in Barcelona, Spain, told the FENS Forum.
The concept of food addiction as a behavioural disorder is still controversial, but the Yale Food Addiction Scale (YFAS 2.0), which is based on diagnostic criteria for substance dependence in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM–5), is widely used in clinical settings.
“A number of factors contribute to food addiction, which is characterised by loss of control over food intake and is associated with obesity, other eating disorders and alterations in the composition of bacteria in the gut – the gut microbiome. Until now, the mechanisms underlying this behavioural disorder were largely unknown,” said Professor Martín-García.
Most research into food addiction has been done in mice, who cannot fill out a questionnaire. Instead, diagnosing them involves observing three particular behaviours: persistent food seeking, high motivation to obtain food, and compulsivity-like behaviour.
This trial, published in the journal Gut, involved both mice and people.
The gut microbiota of both species (it’s very hard not to say of mice and men) was examined via their faeces. In both humans and mice, the abundance of one species of bacteria and lack of the other was associated with addictive behaviour. The researchers also found correlations at the genus and family level with specific types of behaviour.
The 88 humans in the Spanish study were given the YFAS 2.0 questionnaire to determine if they were addicted to food.
Two interventions were carried out on the mice. Some were given nothing (the control group), some were given lactulose and rhamnose (prebiotics), others Blautia wexlerae as a probiotic. The latter is an anaerobic bacteria, making it difficult to use therapeutically, whereas the former could be used by humans.
All the mice were trained to release chocolate-flavoured pellets from a box by pressing a tiny lever and were observed to see if their behaviour matched the criteria for addiction.
(The Back Page will spare you the diagrams showing stylised rats braving electric shocks to get those damned pellets.)
Both treatments seemed to prevent addiction from developing.
Mice receiving rhamnose were less compulsive about trying to get the chocolate pellets compared with the control mice. Around 30% of the control mice met two to three of the criteria for addiction, while none of the rhamnose mice did.
The mice who were given B. wexlerae were less motivated and compulsive about getting those pellets. At a late stage of the study, 21% of the control group mice met two to three addiction criteria, compared to none of the mice receiving B. wexlerae.
Given the rising rates of obesity and its attendant comorbidities, these findings could really help people to identify, treat or prevent the development of food addiction that can lead to obesity, the researchers said.
“We have demonstrated for the first time a direct interaction between the gut composition and brain gene expression, revealing the complex and multifactorial origin of this important behavioural disorder related to obesity,” Professor Martín-García told the forum.
“Understanding the crosstalk between alterations in behaviour and bacteria in the gut constitutes a step forward for future treatments for food addiction and related eating disorders.”
Send chocolate-flavoured pellets of research goodness to penny@medicalrepublic.com.au.
