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The Inflammation - Depression Connection
by Ron Hoggan

Prozac, a brand name for fluoxetine, and Paxil, a brand name for paroxetine, are members of a relatively new class of antidepressants called "selective serotonin reuptake inhibitors (SSRI)" (1). Just as the classification suggests, these drugs increase the activity of the neurotransmitter, serotonin, which works to alleviate depression. It seems odd that so many people are now taking these SSRIs. Is there something wrong with the constitution of the human animal that does not allow us to ward off depression? That seems unlikely. Depression, in the natural selection process of the last 100,000 years or so, would most likely have resulted in trimming folks with a propensity for depression from the gene pool.

Recent changes in our environment seem a more likely cause. What if the root of our depressions is, in part, the result of large-scale consumption, by other parts of the body, of serotonin reserves. This might explain a shortage of serotonin in the brain, and a need for inhibition of reuptake.

What other uses does the body make of serotonin? Well, it is used in the process of clotting blood, and it is also employed in the inflammatory process (2).

Since untreated celiac disease is typified by a chronic inflammation in the small intestine (3), and since it has been demonstrated that gluten, in those with celiac disease, causes microvascular leakage, as indicated by fibrinogen release (4), and intestinal bleeding (5), there is good cause to suspect that celiac-associated depression, is caused, in part at least, by serotonin deficiency.

Of course, only about one half of 1% of the population has celiac disease. That does not explain the broad usage of these SSRIs. Something else might, though. From 5% to 15% of the population demonstrates antigliadin antibodies. Is it possible that there a similar dynamic of intestinal inflammation resulting in serotonin depletion in folks with gluten intolerance? Is it also possible that folks with other food intolerances suffer similar intestinal inflammation, which also depletes serotonin reserves?

Investigation of these matters would seem a valuable enterprise.


  1. _Canadian Medical Association New Guide to Prescription and Over-The-Counter Drugs_ First Edition: 1996, Berner & Rotenberg Eds. Readers' Digest, Montreal, Que. pp 318, 422.
  2. Tortora & Anagnostakos _Principles of Anatomy and Physiology_ Sixth Ed. Harper & Row, New York, 1990 pp 558
  3. Marsh, MN "Gluten, Major HIstocompatibility Complex, and the Small Intestine" Gastroenterology 1992; 102: 330-354.
  4. Marsh MN, _Immunopathology of the Small Intestine_ John Wiley & Sons, Toronto, 1987; pages 374-377.
  5. Fine, KD "The Prevalence of Occult Gastrointestinal Bleeding in Celiac Sprue" NEJM 1996; 334:18