Melatonin has long been tapped by tired travelers to adjust to new time zones.
As a natural hormone in mammals, melatonin is now being explored for its role in disease, as demonstrated by its strong connection to gut microbiota and inflammation. Pointedly, metabolic disorders and intestinal diseases are accumulating relevant results pointing to potential treatment options.
In the first case, melatonin has a role in weight and metabolism: it reduces body weight, liver steatosis, and low-grade inflammation and improves insulin resistance in high fat diet-fed mice, according to research.
Scientists believe that one significant pathway by which melatonin operates may be through gut microbes, which are implicated in metabolic disease.
The study on mice from Beijing, China published in the Journal of Pineal Research revealed that melatonin caused changes in gut microbiota. The researchers then proposed a potential manner by which melatonin may reduce obesity and its related disorders.
Gut microbe changes with melatonin
- Reduced Firmicutes-to-Bacteroidetes ratio—a known obesity marker
- Increased mucin-degrading bacteria Akkermansia, linked with healthy mucosa.
Secondly, in the intestines, melatonin mediates mucosal immune cells, microbial metabolism, and rhythm crosstalk. A 2019 paper published in Medicinal Research Reviews online examines these processes that control the actions of melatonin in gut-microbiome-immune axis.
Probiotics and melatonin
Probiotics are already used successfully to treat irritable bowel syndrome (IBS), but the exact mechanism remains unclear. One pertinent trial looked at the effects of a probiotic on symptoms, psychological and sleep parameters, and pain sensitivity in IBS, and related these factors to melatonin levels.
The study: Forty-two IBS patients were randomly assigned to receive VSL#3 or placebo for 6 weeks. Subjects completed bowel and psychological questionnaires, underwent rectal sensitivity testing and saliva melatonin assays.
Results were encouraging.
The probiotic improved symptoms and increased rectal pain thresholds. Furthermore, improvement correlated with a rise in morning melatonin in subjects with normal circadian rhythm. Probiotics may act by influencing melatonin production, therefore ameliorating IBS symptoms. The study was published in Digestive Diseases and Sciences online.
This is exciting data. Even after travelers load up on airplane food, melatonin may interact with our microbes to prevent weight gain or stomach upset.
The interplay of melatonin and microbes makes for evocative research. Probiotics appear to have potential in influencing this crosstalk to alleviate various disease states.