How Inflammation Interferes with Serotonin Production

What Are Neurotransmitters?  

Neurotransmitters are chemicals that allow one neuron to communicate with another. Every thought, emotion, and memory involves millions of neurons working together. Without neurotransmitters, that communication would not happen.

Drug Therapy Focuses on Neurotransmitters—So Do We  

One reason people are prescribed SSRIs is to increase serotonin, which is a neurotransmitter. It boosts mood, promotes feelings of calm and focus, and regulates sleep cycles, appetite, and memory. It is commonly known as the body’s natural “feel-good” chemical. This is a simplification, but it is adequate for our discussion.

Because serotonin functions as both a brain neurotransmitter and a gut hormone, inadequate serotonin can have both physical and psychological symptoms. This is the reason that current drug therapy focuses on boosting serotonin.

Psychological & Physical Symptoms of Low Serotonin  

Inadequate serotonin production can lead to depression, anxiety, panic, irritability, problems with cognition, and impulsive behavior. Physical symptoms can include insomnia, chronic fatigue, digestive problems, and hypersensitivity to pain.

Current treatment for low serotonin is to give medication, usually SSRIs. In Part 1 we saw that this is not a particularly effective approach [1-3]. If you really want adequate serotonin production, you need to get inflammation under control.

Inflammation Interferes with Serotonin Production  

Without turning this into a chemistry lesson, look at the infographic at the top of the page. Follow the arrows, they represent chemical reactions. Tryptophan, in the upper left corner, turns into 5 HTP, which becomes serotonin. That is normal.

Inflammation Hijacks Tryptophan and Makes Harmful Stuff 

If you look to the right of the arrow that goes from tryptophan to kynurenine, you see IDO and a box with some chemical names in it. That is simply showing you chemicals created from inflammation. When they are next to an arrow representing a chemical reaction, it means that those chemicals drive that reaction. Inflammation interferes with serotonin production.

To make matters worse, instead of producing serotonin, the pathway produces quinolinic acid. Quinolinic acid overstimulates NMDA receptors. In excess, this becomes toxic to nerve cells They are linked to depression and dementia.

The Problem Goes Beyond Serotonin: In inflammatory states, antidepressants may fail not because serotonin doesn’t matter — but because the immune system has hijacked tryptophan metabolism. Inflammation activates Indoleamine 2,3-Dioxygenase (IDO). IDO prevents the body from making serotonin from tryptophan. Taking a drug to boost serotonin without addressing inflammation is a lot like bailing water out of a boat without fixing the hole.

Diet and Serotonin

Perhaps the best way to get inflammation under control is through diet. The Roadmap to Health is an effective anti-inflammatory diet and a good place to start. By reducing inflammation, you may also improve your body’s ability to produce serotonin naturally.

Selected References:

1. Psychother Psychosom 2010;79:267–279 Efficacy and Effectiveness of Antidepressants: Current Status of Research
2. British Medical Journal, (Br J Psychiatry. 2011 Jan;198(1):11-6, sup 1) Efficacy of antidepressants and benzodiazepines in minor depression: systematic review and meta-analysis
3. PLOS February 26, 2008 Initial Severity and Antidepressant Benefits: A Meta-Analysis of Data Submitted to the Food and Drug Administration