Gut feelings

Consumed by food cravings? It might be your gut bacteria talking

Written by Megan Rossi

Ever felt that you were unable to control your cravings? New research suggests that when it comes to food cravings, perhaps we should be pointing the finger not at ourselves, but at the trillions of bacteria that call our gut home.

This colony of bacteria that we host from birth, which scientists call our gut microbiota, outnumbers human cells 10 to one. In light of this microbial dominance, it would be rather naïve of us to credit all our food cravings to our minds rather than to our matter. This raises the humbling question: are our gut microbiota our true mastermind?

Does the evidence stack up?

Recent studies have shown our gut microbiota not only affect our mood and satiety by creating happiness (serotonin and dopamine) and appetite (leptin and ghrelin-like) hormones, but can manipulate our taste buds to make us crave different foods. This discovery has taken the scientific world by storm, uncovering direct pathways through which our gut microbiota communicate with our brain.

It’s a phenomenon termed the ‘gut-brain axis’. Researchers from Switzerland have proposed this gut-brain axis may explain why some of us are ‘chocolate-desiring’ and others ‘chocolate- indifferent’, with suggestions that the two behaviour types host different gut microbial profiles.

Animal studies have also shown that manipulation of the gut microbiota can predispose animals to a preference towards sweet or fatty food. These findings are just another piece of the pie linking the gut microbiota and obesity.

"It’s a phenomenon termed the ‘gut-brain axis’. Researchers from Switzerland think this may explain why some of us crave chocolate more than others."

Is our gut bacteria making us fat?

According to the latest research from the US, our gut bacteria may bias us towards obesity, with a study in twins demonstrating distinct differences in the gut bacterial profiles between obese and lean twins. Further to this, transferring the fecal-gut bacteria from an obese twin to germ-free mice resulted in transmission of obesity compared to the mice who received the lean co-twin’s sample.

This landmark finding suggests that obesity may, in fact, be contagious, explaining why cohabitating partners host more similar gut profiles compared to people who live apart. This finding provides new insight into the obesity epidemic spreading across Australia.

Feeding our inner universe

Just like the gut microbiota can manipulate some of our food choices, research has revealed that we, in turn, can manipulate them. Choosing plenty of high fibre foods is thought to be key in selectively promoting the growth of a healthy gut profile. In particular, including unrefined whole grains, fresh fruits and plenty of vegetables, including legumes, is associated with an optimal gut profile and healthy body weight.

Some simple tips to up your fibre intake include substituting some of the meat in dishes for legumes, such as chickpeas or lentils, and moving away from traditional white rice and pasta to more of the ancient wholegrains, such as quinoa and buckwheat. For more tips visit the Dietitians Association of Australia website.

With this new research in mind, next time you feel a craving coming on, instead of negotiating with your conscience, perhaps check-in with the health of your gut microbiota.

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Written by Megan Rossi

Megan Rossi has worked as a clinical dietitian for a major tertiary hospital, a consultant dietitian for Dietitian's Association of Australia and a sports nutritionist for the Australia Olympic Synchronised Swimming team.

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