Welcome to my blog “Melatonin And Gut Health”.
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Melatonin And Gut Health
Since the gut contains at least 400 times more melatonin than the pineal gland, a review of the functional importance of melatonin in the gut seems useful, especially in the context of recent clinical trials. Melatonin exerts its physiological effects through specific membrane receptors, named melatonin-1 receptor (MT1), MT2 and MT3.
These receptors can be found in the gut and their involvement in the regulation of GI motility, inflammation and pain has been reported in numerous basic and clinical studies.
How Does Melatonin Help IBS?
The gastrointestinal tract represents the most important extrapineal source of melatonin.
Putative role of melatonin in IBS treatment include (1, 3):
- Analgesic effects – it may help to alleviate abdominal pain and influence the sensation of abdominal distention in IBS patients.
- Regulator of gastrointestinal motility – it may improve the bowel habits and alleviate abdominal pain or distention in IBS patients.
- Sensation to sleep promoter – may be useful to treat the sleep disturbance of IBS patients.
- Melatonin has mood regulation and anti-stress effects which could help alleviate the abnormal psychological parameters observed in IBS patients.
- The release of peptides involved in energy balance such as peptide YY
Several well-designed placebo- controlled trials in IBS patients had consistently showed improvement of abdominal pain when taking 3 mg of melatonin with no serious side effect (1).
Some studies suggest a possible role of melatonin in the pathophysiology of IBS. For example, disturbances in melatonin metabolism and secretion may be involved in different GI diseases including IBS. In a clinical trial involving patients with IBS, the beneficial effects of melatonin were obvious in the relief of symptoms such as abdominal pain, abdominal distension and abnormal sensation of defecation. Melatonin may exert its beneficial effects in IBS through effects on the central nervous system, via an enhancement of the cellular and humoral immune systems, or by antagonising corticoid- and serotonin-mediated effects. However, mela- tonin does not influence sleep pattern or psychological well-being in patients with IBS.
Melatonin And Motility
One of the key connections between melatonin and gut health is related to melatonins effect on gut motility. Low doses melatonin improves gastrointestinal transit and affect MMC. Melatonin reinforce MMCs cyclic pattern but inhibits spiking bowel activity (2).
Melatonin reduced the tone but not amplitude or frequency of contraction. Melatonin is a promising therapeutic agent for IBS with activities independent of its effects on sleep, anxiety or depression. Since of its unique properties melatonin could be considered for prevention or treatment of colorectal cancer, ulcerative colitis, gastric ulcers and irritable bowel syndrome (2).
Melatonin may also have a beneficial effect in reversing lipopolysaccaride-induced motility disturbances. LPS are remnants of gram-negative bacteria, normal inhabitants of the large intestine. But if these overgrow, we can end up with a high LPS burden in the gut that may influence motility.
Melatonin And Gut Inflammation
By preserving the mucosal cell integrity and inhibiting the accumulation of neutrophils, melatonin exerts protective effects against inflammation in the gut. Melatonin was shown to reduce the severity of intestinal inflammatory pathologies such as colitis in animal models
Melatonin treatment also causes a substantial reduction of FasL gene activation, which is known to induce a pro-inflammatory response characterised by a release of IL-1b. Blocking the action of these cytokines has been shown to delay the onset of experimental colitis, to suppress inflammation and to ameliorate colonic damage.
Melatonin And Colon Cancer
Following the identification of melatonin binding sites in human colon tissue from patients with carcinoma of the rectum and the colon, a possible role of melatonin in colorectal cancer was addressed in several studies.
The anti-oxidative and anti-inflammatory actions of melatonin, changing the oxidative status and reducing the production of nitric oxide by cultured colon cancer cells, may also be directly involved in the onco-static properties of melatonin.
In clinical trials, melatonin was shown to have cyto- protective effects that may be involved in increasing the efficacy of cancer chemotherapy and improving survival. Melatonin co-treatment was also shown to reduce the adverse toxicities of chemotherapy and radiotherapy.
Other clinical studies showed that melatonin co-treatment with IL-2, Aloe vera or fish oil partly enhanced the effect of chemotherapy and reduced the toxicity in colorectal carcinoma. However, melatonin did not have any pro- tective effect on irradiation-induced lymphocytopenia in patients with colorectal carcinoma.
The link between melatonin and gut health is clear. Melatonin is a relatively safe drug that possesses potential in treating IBS. Its attractiveness also stem from its relative low cost to the patients. Future studies should focus on melatonin effect on gut mobility especially in IBS-C patients as well as its true central nervous system effect in view of high placebo rate often observed in IBS patients (1).
The uncommonly high-safety profile of Mel. also bolsters this conclusion.