Written by Chrystal Moulton, Staff Writer. 57 children with sleep problems were given 250 mg pure tryptophan and compared to those with no tryptophan or taking 250 mg tryptophan from butternut squash seed meal. Pure tryptophan did somewhat better than the food tryptophan during the test for most sleep factors, except food tryptophan did much better at reducing time awake in the middle of the night and more improved after the test.
Tryptophan is an essential amino acid known for its role in the production of serotonin and melatonin. The general recommended daily intake of tryptophan is 4mg/kg of body weight for adults (1). Tryptophan, though, is not as abundant in foods as other amino acids. Nonetheless, it plays a vital role in various physiological functions in the body, especially sleep. Numerous interventions have been used to combat sleep disorders, but tryptophan remains an essential factor in the treatment of such disorders. The main issue with tryptophan, however, is that in its natural form (protein bound), it is outcompeted by other amino acids for uptake into the brain. Previous research suggests that glucose and insulin levels influence tryptophan uptake into the brain (2,3).
In a recent study (4), researchers wanted to know if pharmaceutical grade tryptophan could be replaced with a protein rich in tryptophan combined with sufficient carbohydrates to illicit the transport of tryptophan into the central nervous system. In the current study, sleep parameters were used as a dependent variable reflecting tryptophan’s uptake into the brain. Participants were chosen if they had difficulty going to sleep or maintaining sleep 3+ nights/week for three months or more. Participants were excluded if they had heart diseases, mental health issues, food allergies, diabetes, sleep apnea, and if pregnant or a shift worker. Fifty-seven volunteers were randomly assigned into one of three groups: 18 participants were assigned to Food 1 group and received protein bound tryptophan (as a food bar), 16 participants were assigned to Food 2 group and received pharmaceutical grade tryptophan (as a food bar), and 15 participants were assigned to Food 3 group and received placebo (as a food bar). The average age was about 50 years old and the average weight 70 kg. The protocol was a randomized double-blind placebo controlled parallel study. Researchers compared the effects of 250 mg of pharmaceutical grade tryptophan and 250 mg protein bound tryptophan (from butternut squash seed meal) on insomnia. In the first week of a 3 week protocol, participants recorded objective information in a sleep diary about the quality of sleep without their respective treatments. Sleep diaries required volunteers to record the total time of sleep, efficiency of sleep (time asleep/total time in bed x 100), time awake at night, and time awake during the middle of the night. Subjective scores on restfulness were also gathered through the diary. In the second week, participants were given another sleep diary and their specific treatments based on the food group to which they were randomly assigned. In the third week, volunteers were taken off the treatments and given another sleep diary in order to record sleep quality post-treatment. Each participant met with a nurse on a regular basis, turned in their diaries, and discussed any issues with their treatment or the protocol.
Results are displayed in Table 1.
Table 1. Study Results
| Sleep Variables | Food 1 (natural source: butternut squash) | Food 2 (pharmaceutical grade) | Food 3(placebo) |
| Total sleep time | ↑5.5% during treatment, ↑6.5% post-treatment (p<0.10) | ↑13% during treatment (p<0.01), ↓4.1% post-treatment (p>0.10) | No significant increase during treatment, ↑6.6% post-treatment (p<0.01) |
| Sleep efficiency | ↑5.19% during treatment (p<0.05), ↑1% post-treatment (p>0.10) | ↑7.36 during treatment (p<0.01), ↓1.9% post-treatment (p>0.10) | ↑2.1% during treatment , ↑4.1% post-treatment (p>0.10) |
| Total awake time | ↓19.2% during treatment (p<0.01), no significant reduction post-treatment | ↓22.1% during treatment (p<0.01), no significant reduction post-treatment | ↓6.1% during treatment (p>0.10), ↓16.7% post-treatment (p<0.05) |
| Time awake middle of night | ↓39.3% during treatment (p<0.01), non-significant increase post-treatment | No significant reduction during or after treatment | No significant reduction during or after treatment |
| Sleep quality index | ↑12.2% during treatment (p<0.05), ↓4.95% post-treatment (p>0.10) | ↑11.8% during treatment (p<0.05), ↓2.88% post-treatment (p>0.10) | ↑9.2% during treatment (p>0.10), ↑5.62% post-treatment (p>0.10) |
In all, the research shows that protein bound tryptophan is comparable to pharmaceutical grade tryptophan in treating symptoms of insomnia. One result however that differs between the protein-bound tryptophan and the pharmaceutical grade is the time awake during the middle of the night. Protein bound tryptophan was the only treatment that reduced this symptom by about 23 minutes (39.3 %). Researchers believe this happened because protein bound tryptophan is released slower. And what’s more important, this release of tryptophan from the protein is done at the moment insulin concentration in the blood stream is high enough to facilitate transport of tryptophan across the blood brain barrier. More studies are needed to know the amount of tryptophan that is released and transported into the central nervous system.
Source: Hudson, Craig, et al. “Protein source tryptophan versus pharmaceutical grade tryptophan as an efficacious treatment for chronic insomnia.” Nutritional neuroscience 8.2 (2005): 121-127.
© Taylor and Ferancis LTD
Posted February 18, 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:
- Moehn S, Pencharz PB, Ball RO. Supplement: 8th Workshop on the Assessment of Adequate and Safe Intake of Dietary Amino Acids: Lessons Learned Regarding Symptoms of Tryptophan Deficiency and Excess from Animal Requirement Studies J. Nutr. 2012 142: 12 2231S-2235S
- Fernstrom JD, Faller DV. Neutral amino acids in the brain: changes in response to food ingestion. J Neurochem. 1978 Jun;30(6):1531-8.
- Markus CR. Dietary amino acids and brain serotonin function; implications for stress-related affective changes. Neuromolecular Med. 2008;10(4):247-58. Epub 2008 May 31
- Hudson C, Hudson SP, Hecht T, MacKenzie J. Protein source tryptophan versus pharmaceutical grade tryptophan as an efficacious treatment for chronic insomnia. Nutr Neurosci. 2005 Apr;8(2):121-7.
