The Link Between Constipation and Depression

The Link Between Constipation and Depression 


Given what we now know about the microbiome and mood, it is no shock to find out that there is a relationship between gut disorders and depression. This study, using a mouse model, sought to find out why chronic constipation and depression often occur together.

About one third of people with depression also suffer from constipation (the percentage is higher in older adults).

While some of the medications used to treat depression can slow bowel movements and reduce gut motility, not all patients use these medications, so the explanation had to involve more than just side effects from drugs.

The researchers involved in this mouse study chose to examine the role of the neurotransmitter serotonin in these two conditions. They chose this avenue because of two things. One, people with depression are currently believed to have lower levels of serotonin in their brains, and two, neurons found in the gastrointestinal tract use serotonin.

Since the stomach has more neurons than the spinal cord, and uses most of the same neurotransmitters as the brain, scientists often refer to the stomach as the “second brain.”

Their first step was to reduce levels of serotonin in the guts of the experimental mice, to see if that would induce constipation. The results of lowering serotonin levels in the gut were threefold: the overall number of neurons dropped, the gut lining began to deteriorate, and the speed of movement through the gut was reduced. “Basically, the mice were constipated, and they showed the same kind of GI changes we see in people with constipation.”

Next, the scientists tested an “experimental drug”, 5-HTP, the amino acid precursor of serotonin. I find this somewhat amusing, given that 5-HTP has been available in health food store for decades. What is somewhat different about their approach, however, was they used a slow-release version of 5-HTP, which, while not apparently available in Canada, is available in the U.S. (Buy on-line)

The 5-HTP did boost levels of serotonin in the guts of the experimental mice, and this in turn relieved the symptoms of constipation, as well as returning the gut motility to normal. But, more than that, 5-HTP (slow release) increased the number of neurons in the gut, returning them to normal levels. Neurogenesis is well known to occur in the brain, but this is one of the few instances of it being observed to occur in the gut. This new cell-receptor generation is even more interesting than simply raising levels of the neurotransmitter (serotonin), since it implies a potential for healing both the gut lining, and permanently reversing depression.

The scientists involved in this study now think that promoting neurogenesis may also treat constipation that has no relationship to depression.

“We see a reduction of neurons in the GI tract with age, and that loss is thought to be a cause of constipation in the elderly. The idea that we may be able to use slow-release 5-HTP to treat conditions that require the development of new neurons in the gut may open a whole new avenue of treatment.”

The two prime authors of the study now “hold equity in Evecxia Therapeutics, a company founded to develop a slow-release 5-HTP drug for the management of serotonin-related disorders.”

They are aware that immediate-release 5-HTP is commonly available, but this form has not demonstrated the same benefits. Regular 5-HTP does convert into serotonin, but is quickly broken down by the body, and so cannot have the same effect, and in fact, according to these scientists, “it cannot impart any benefits.”

I must disagree, since thousands of users of conventional 5-HTP do find some benefit. However, perhaps it is unable to regenerate new neurons in the gut, in the way that the slow-release version can, and thus may not be as helpful for healing gut lining, nor for preventing constipation.


Finally, as we are on the subject of depression, I would be remiss if I did not mention vitamin D. As I like to point out to clients I am consulting with, there are many vitamin D receptors in the brain, and D deficiency is linked to autism, schizophrenia, anxiety, insomnia and depression (not to mention other neurological conditions). (Study) Therefore, when dealing with any of these conditions, the first thing to do is ensure that one as adequate vitamin D levels. (Quick D)

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