Melatonin: Mechanisms of action and it’ s amazing role beyond sleep
An interiew with Dr Deanna Minich
Dr Deanna Minich is a nutritional scientist, international lecturer, and certified functional medicine practitioner. She has a Master of Science degree in human nutrition and dietetics and has completed her doctorate in the nutritional field. Deanna is the author of six books, including The Rainbow Diet and Whole Detox, and has published more than 50 scientific publications and book chapters. Recently, Deanna published a comprehensive scientific review on melatonin, where she referred to melatonin deficiency as a darkness deficiency. The fx Medicine podcast from which this article is adapted explores the role of melatonin beyond sleep. It was hosted by Dr Adrian Lopresti. This article is published with the kind permission of fx Medicine.
Deanna: Melatonin is an indolamine. it looks like a neurotransmitter with an amine group attached to it. What’ s unique about melatonin is that it’ s everywhere, absolutely everywhere. In nature it’ s in animals, in our bodies. We make it through the pineal gland. You were asking, where is it made? There are different types of melatonin in the body, so there is some nuance in regard to its source.
Pineal melatonin is part of the endocrine system. When the pineal gland produces melatonin in response to darkness it is sent systemically to connect to different cells and to basically key into the clock system. That’ s the form of melatonin that most people are aware of.( The other types of melatonin are the autocrine and paracrine).
The mitochondria are huge producers of melatonin, so every cell type that contains mitochondria would be producing melatonin, which means that all body tissues harbour melatonin. This is because melatonin is amphiphilic: it can live in fatty areas of the body, and it can also live in water compartments, like the blood. So you’ re going to find it in the eye, the skin, the liver, the kidney, the thyroid, the thymus, skeletal muscle, and the reproductive system.
Adrian: And I read there’ s about 400 times more melatonin in the gut mucosa than the pineal gland. So, what’ s the role of melatonin in the gut?
Deanna: I don’ t think we fully understand it, but here’ s what I see in the science. You’ re right. There’ s about 400 times higher concentration in the gut than in the pineal gland, and it’ s not released in accordance with darkness. So the trigger to produce melatonin is different in the gut. It seems to be produced in response to a meal: there’ s a postprandial effect. Now, we know that most neurotransmitters are produced in higher amounts in the gut anyway. Melatonin is no exception. We also see that with serotonin, we see it with a number of other neuroactive compounds. But what we think is that it may play a role in gastrointestinal motility.
There are some studies looking at whether or not melatonin is modulating the gut microbiome: modulating secretions in the gastrointestinal tract. And of course, we know that, aside from the GI tract, there’ s a role for melatonin in the immune system, and 70 % of the immune system is actually housed in the gut. So, there might actually be a role right there locally, related to the immune system.
Adrian: And is it the microbiota that’ s making the melatonin? Is that where it’ s coming from?
Deanna: From my understanding, it’ s more the enterochromaffin cells that are releasing serotonin and melatonin. So it’ s more the neuroendocrine cell types within the gut, which iswhy you find it pretty much throughout the gastrointestinal tract. I would say it’ s not limited to the gut microbiome, because you do find it in the esophagus all the way down to the rectum. Therefore, I think it’ s probably connected to the neuroendocrine fraction, perhaps as it connects to the smooth muscle.
Adrian: You also mentioned that it’ s produced by the mitochondria. Is that then having a role in ATP production and energy production?
Deanna: Yes. What we think is happening with the mitochondria is that it’ s modulating the mitochondria. So, what is the role of the mitochondria? Well, it’ s the main hub of metabolism. So, oxidative phosphorylation, the metabolic pathway by which cells use enzymes to oxidize nutrients; there’ s a lot in the way of reactive oxygen species that get produced by that metabolic process. And so it’ s hard to say exactly what melatonin
162 | vol31 | no3 | JATMS