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Randomised controlled trial of the effects of L-ornithine on stress markers and sleep quality in healthy workers

Mika Miyake1*, Takayoshi Kirisako1, Takeshi Kokubo1, Yutaka Miura1, Koji Morishita2, Hisayoshi Okamura3 and Akira Tsuda4

Author Affiliations

1 Research Laboratories for Health Science & Food technologies, Research & Development Division, Kirin Co., Ltd., 1-13-5, Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan

2 Healthcare Products Development Center, Kyowa Hakko Bio Co., Ltd., 2, Miyukigaoka, Tsukuba, Ibaraki, 305–0841, Japan

3 Cognitive and molecular of Brain disease, Kurume University, 67, Asahi-machi, Kurume, Fukuoka 830-0011, Japan

4 Department of Psychology, Kurume University, 1635, Miimachi, Kurume, Fukuoka 839-8502, Japan

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Nutrition Journal 2014, 13:53  doi:10.1186/1475-2891-13-53

Published: 3 June 2014



L-ornithine is a non-essential, non-protein amino acid. Although L-ornithine is contained in various foods, the amount is usually small.

Recently, studies have shown that orally administered L-ornithine reduced the stress response in animals.

From these findings, we speculated that L-ornithine may play a role in the relieve of stress and improve sleep and fatigue symptoms in humans. Through a randomised, double-blind, placebo-controlled clinical study, we asked if L-ornithine could be beneficial to stress and sleep in healthy workers.


Fifty-two apparently healthy Japanese adults who had previously felt slight stress as well as fatigue were recruited to be study participants and were randomly divided into either the L-ornithine (400 mg/day) or placebo group. They orally consumed the respective test substance every day for 8 weeks. Serum was collected for the assessment of cortisol and dehydroepiandrosterone-sulphate (DHEA-S). Perceived mood and quality of sleep were measured by the Profile of Mood States (POMS), Athens Insomnia Scale (AIS), and Ogri-Shirakawa-Azumi sleep inventory MA version (OSA-MA).


Serum cortisol levels and the cortisol/DHEA-S ratio were significantly decreased in the L-ornithine group in comparison with the placebo group. Also, anger was reduced and perceived sleep quality was improved in the L-ornithine group.


L-ornithine supplementation has the potential to relieve stress and improve sleep quality related to fatigue, both objectively and subjectively.

L-ornithine supplementation; Stress and sleep; Clinical trial