Written by Chrystal Moulton, Staff Writer. In a study with 45 children with sleep terrors, those taking 250mg tryptophan could significantly reduce heart rate in association to social anxiety (formerly considered “shyness”).
Social anxiety disorder is one of the most common anxiety disorders in existence. About 50% of children 11 years old and 80% of 20 year olds suffer from social anxiety. At one time, it was only viewed as shyness. People with social anxiety avoid the scrutiny of others for fear of embarrassment and humiliation. Many of us suffer or have felt some form of social phobia at some point in our lives. However for people with social anxiety disorder, the intense fear of social environment permeates every part of their lives and becomes a gateway for alcohol abuse and depression.(1) Tryptophan, a key amino acid for the production of serotonin and melatonin, has been shown to positively affect mood. Nonetheless, its availability is hindered by other large neutral amino acids that simultaneously compete for uptake into the central nervous system. Some previous studies have shown that glucose intake can increase tryptophan’s bioavailability.(2)
In the current study,(3) researchers wanted to see if tryptophan accompanied by glucose could relieve symptoms of social anxiety disorder. Seven people with social anxiety disorder were recruited to the double-blind placebo protocol that was broken down into 2 sessions. In the first session, 2 participants were randomly assigned to receive the placebo which was a bar composed of dried fruit and dextrose consisting of 50 g of carbohydrates. The 5 other participants received a bar containing 250 mg of tryptophan. They measured heart rate using a heart monitor as an objective measure of anxiety and anxiousness was measured using the Endler Multidimensional Scale (a psychological questionnaire). Participants completed the Endler Social Anxiety Assessment and were instructed to consume the bars given. Their heart rate was then measured and recorded 5 minutes before they were put into an anxiety provoking situation. Researchers then measured their heart rate again after 5 minutes during the anxiety provoking stimulus and once more 5 minutes after the stimulus. Again, participants completed the Endler Assessment on Perceived Anxiety. After a 7-day washout period, session 2 began and the groups were reversed. The 2 participants originally assigned to the placebo were given the treatment (tryptophan bar) and the 5 participants originally assigned to the treatment were given the placebo. Then, the same procedures detailed in session 1 were followed. Researchers hypothesized that the tryptophan bar would help decrease the level of subjective or perceived anxiety and objective anxiety due to the clinical stimulus.
Comparing Endler assessment scores from baseline to endpoint during each session, the placebo group (11.83) had a higher average score (reflecting a higher level of anxiety) than the treatment group (10.08) however, the difference was not significant (P>0.05). Endler scores also demonstrated a non-significant reduction whenever scores were taken during the treatment (tryptophan bar). Heart rate was significantly higher during the anxiety stressor (91.50 beats/min) than at baseline (80.53 beats/min) (p<0.01). Researchers also found that the ratio of heart rate variation during the stressful stimulus was significantly lower than baseline across treatment conditions (1.31) than at baseline (1.48) (p<0.025). More notably the difference between the heart rate ratio when the subjects took the placebo versus the treatment was significantly different (p<0.01). This last result seems to suggest that the tryptophan may help to reduce objective parameters of social anxiety (in this case, heart rate). However, since this was a pilot study, a larger test group and a longer effect period would be needed to clearly assess the effects of tryptophan on social anxiety.
Source: Hudson, Craig, Susan Hudson, and Joan MacKenzie. “Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study This article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products.” Canadian journal of physiology and pharmacology 85.9 (2007): 928-932.
© 2007 NRC Canada
Posted February 27, 2014.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
- Stein MB, Stein DJ. Social anxiety disorder. The Lancet. Mar-April 2008, 371 (9618): 1115-1125.
- Martin-Du Pan R, Mauron C, Glaeser B, Wurtman RJ, Effect of various oral glucose doses on plasma neutral amino acid levels. Metabolism, September 1982, 31(9): 937-943
- Hudson C, Hudson S, MacKenzie. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. J. Can J Physiol Pharmacol. 2007 Sep;85(9):928-32.
