The Serotonin Connection to Anxiety

Anxiety disorders affect millions of Americans. We now know that these troubling emotions can be caused by imbalances in body chemistry. In numerous research studies, low serotonin has been identified as a factor in anxiety disorders. Since serotonin is derived in the body from the nutrient tryptophan, it is not surprising that the research links both low tryptophan and low serotonin to anxiety conditions. Studies have also found that tryptophan supplements reduce feelings of anxiety.

. Low serotonin is implicated in anxiety

Double-blind placebo-controlled studies are considered the gold standard of research. A study at the Department of Biological Psychiatry of University Hospital in Utrecht , the Netherlands , reported the link between serotonin and anxiety: "The results support the hypothesis that brain serotonergenic [serotonin] pathways are involved in the [development] of anxiety disorders, particularly in agoraphobia and panic disorders."

RS Kahn and others. " Effect of a serotonin precursor and uptake inhibitor in anxiety disorders; a double-blind comparison of 5-hydroxytryptophan, clomipramine and placebo." International Clinical Psychopharmacology . January 1987; Vol 2, No 1: pages 33-45.

Other studies reported, "Recent research has identified that various abnormalities in serotonergic [serotonin] function are involved in the pathogenesis [and development] of depression and anxiety."

D Baldwin and S Rudge . "The role of serotonin in depression and anxiety." International Clinical Psychopharmacology . January 1995 Supplement, Vol 4: pages 41-45.

A review of the medical literature found that, "In the CNS [central nervous system], serotonin levels have been implicated in the regulation of sleep, depression, anxiety, aggression, appetite, temperature, sexual behaviour, and pain sensation."

TC Birdsall. " 5-Hydroxytryptophan: a clinically-effective serotonin precursor." Alternative Medicine Review . August 1998; Vol 3, No 4: pages 271-280.

. Low tryptophan is linked to anxiety and panic disorders

Researchers at Massachusetts General Hospital in Boston examined the effects of nutritional tryptophan depletion on depressed patients in remission and reported, "Tryptophan depletion was significantly related to increased scores on clinician-rated depression and anxiety scales, and on self-rated depression, anxiety, and somatic [physical] symptoms."

MK Spillmann and others. "Tryptophan depletion in SSRI-recovered depressed outpatients." Psychopharmacology ( Berlin ) . May 2001; Vol 155, No 2: pages 123-127.

A review by researchers at the University of Newcastle in the UK evaluated the research on the role of serotonin on mood disorders and anxiety. They concluded, "Rapid tryptophan depletion has also been reported to exacerbate [aggravate] both panic and aggression in vulnerable individuals."

JG Reilly and others. "Rapid depletion of plasma tryptophan: a review of studies and experimental methodology." Journal of Psychopharmacology ( Oxford ) . 1997; Vol 11, No 4: pages 381-392.

Researchers at the Maastricht University in the Netherlands studied the influence of tryptophan depletion in twenty-four panic disorder patients and observed, "There was a significant increase in anxiety in the depletion group. When we compare the results with earlier panic provocation studies it also seems that...balanced amino acids might have a protective effect against a panic provocation. We observed the panic-enhancing effect of tryptophan depletion as well as the potential protective effect of tryptophan administration in panic disorder patients."

K Schruers and others. " Acute L-5-hydroxytryptophan administration inhibits carbon dioxide-induced panic in panic disorder patients." Psychiatry Research . Dec 30, 2002 ; Vol 113, No 3: pages 237-243.

. Tryptophan has been found to lower anxiety

A program to help people stop smoking at The Fred Hutchinson Cancer Research Center in Seattle investigated the use of tryptophan in smoking cessation. They concluded, " Reported anxiety and other withdrawal symptoms were lower in the tryptophan group compared with control subjects...Tryptophan-treated subjects who could not fully abstain were able to smoke fewer daily cigarettes."

DJ Bowen and others. "Tryptophan and high-carbohydrate diets as adjuncts to smoking cessation therapy." Journal of Behavioral Medicine . April 1991; Vol 14, No 2: pages 97-110