Written by Jessica Patella, ND. In a small human study on a stationary bicycle those taking an ornithine supplement had less reduction in pedalling speed.
Fatigue is one of the most common symptoms people experience, even if they are healthy (1,2). Since fatigue is common and long term chronic fatigue can cause irreversible damage leading to death, clinically proven anti-fatigue agents are very important as a recovery mechanism. Recently, there has been a great interest in natural supplements that conquer fatigue. Fatigue can either be described as mental fatigue or physical fatigue. Physical fatigue is described as difficulty initiating or sustaining voluntary activities. With the recent development of methods for evaluating physical fatigue (3,4), a small scale study was conducted that demonstrated supplementing with L-ornithine helps decrease physical fatigue (2).
The study design evaluated fatigue through a series of methodologies; 1.) subjective rating of fatigue level, 2.) physical performance, and 3.) key blood biochemical parameters. A total of 17 healthy volunteers (40.9 +/- 11.8 years; 9 female, 8 male; body weight 58.2 +/- 9.8 kg; body mass index (BMI), 21.7 +/- 3.1 kg/m2) were randomized in a double-blind, placebo-controlled, 2 way crossover trial in 2 groups. Group 1 received L-ornithine for one week and then was tested for fatigue. After a 4-week washout period (period during which participants did not take any supplements), Group 1 was given a placebo for one week, and then tested for fatigue again. Group 2 did the opposite; taking the placebo first, then L-ornithine. To decrease bias, neither the participants nor the researchers knew who was in Group 1 vs. Group 2.
The participants were given 2 capsules of 500mg L-ornithine twice/day (2000 mg/day total) for 7 days. The day before the fatigue test, participants were all given the same dinner and the same breakfast the day of the test. During breakfast the morning of the test, participants took 6 capsules of placebo or L-ornithine (3000 mg). Then they cycled on a stationary bike for 2 hours (approximately 80% of heart rate). At the end of the cycling period, participants rated their fatigue using a visual analog scale (VAS) ranging from 0 (no fatigue) to 100 (total exhaustion) (5). The participants then took another 6 capsules of placebo or L-ornithine (3000 mg). Then they cycled again for 2 hours and rated their fatigue at the end of this second cycling period. All participants had the same lunch followed by a 4-hour recovery period where participants could read, listen to music or talk. At the end of the day, participants rated their fatigue again (post-recovery).
Physical performance was evaluated having subjects perform a 10 second maximum pedaling using a cycle ergometer at 2 time points; 0.5 hour after the start (0.5 hr.) and 0.5 hour before the end (3.5 hr.) of the load period. Fatigue levels were evaluated by the decrease in pedaling speed from the 0.5 to 3.5-hour points.
Results from the study in the subjective rating of fatigue, demonstrated that all participants taking L-ornithine had a highly significant (P<.01) reduction in the feeling of fatigue at the post-recovery point (minus 7.46 +/- 1.42) when compared to the post-load point (minus 6.32 +/- 1.99). In contrast, no difference was shown in the placebo group between any of the examination points. Within the L-ornithine group, only females demonstrated a significantly (P<.05) smaller increase in fatigue feeling from the preload to post-recovery point (plus 1.89 +/- 2.95) compared to placebo plus 3.62 +/- 2.83).
In the physical performance test, while no difference was shown between the L-ornithine group and placebo group, females in the L-ornithine group had a significantly (P<.05) smaller decrease in pedaling time than males.
Results of blood biochemical evaluations showed L-ornithine also significantly (P<.05) promoted fat metabolism when compared to placebo as determined by decreasing triglyceride levels after 1 week of supplementation, as follows:
| Triglycerides (mg/dL) | Before Load | Recovery |
|---|---|---|
| L-ornithine | 66 +/- 26 | 48 +/- 24 |
| Placebo | 79 +/- 28 | 56 +/- 29 |
Consumption of L-ornithine was shown to increase plasma ornithine at all examination points in the L-ornithine group while the placebo group showed no change. The increase in plasma ornithine was directly correlated to the activation of the urea cycle as shown by a significant (P<.05) increase in plasma alanine and urea (products of ammonia detoxification).
| Plasma Blood Levels | Before Load | Recovery |
|---|---|---|
| Ornithine (nmol/mL) | ||
| L-ornithine | 52.5 +/- 9.5 | 74.3 +/- 11.9 |
| Placebo | 47.832 +/- 8.8 | 44.8 +/- 8.6 |
| Alanine | ||
| L-ornithine | 349.1 +/- 69.8 | 309.2 +/- 42.1 |
| Placebo | 390.3 +/- 90.5 | 289.6 +/- 55.9 |
| Urea | ||
| L-ornithine | 4625.4 +/- 1355.5 | 4473.4 +/- 1185.2 |
| Placebo | 4261.9 +/- 967.6 | 4003.2 +/- 879.8 |
In conclusion L-ornithine decreased physical fatigue in both men and women when evaluated by the subject feeling of fatigue, promoted lipid metabolism and activated the urea cycle to promote ammonia excretion a byproduct of physical exercise. However, only women showed an improvement in physical performance. Although this was a small study with only 17 participants, future research is warranted to confirm these results with more participants. In addition, higher dose levels should be considered to evaluate potential metabolic differences between males and females. It is also important to note the company that manufactures the L-ornithine used in this study funded the research.
Source: Sugino, Tomohiro, et al. “L-ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism.” Nutrition research 28.11 (2008): 738-743.
© 2008 Published by Elsevier Inc.
Posted July 11, 2012.
Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. Visit her website at www.awarenesswellness.com
References:
- Ream E, Richardson A. Fatigue: a concept analysis. Int J Nurs Stud. 1996; 33:519-29.
- T. Sugino, et al. L-Ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism. 2008. Nutrition Research 28: 738-743.
- Ataka S, Tanaka M, Nozaki S, Mizuma H, Mizuno, K, Tahara T, et al. Effects of Applephenon® and ascorbic acid on physical fatigue. Nutrition 2007;23:419-23.
- Mizuno K, Tanaka M, Nozaki S, Mizuma H, Ataka S, Tahara T, et al. Antifatigue effects of coenzymeQ10 during physical fatigue. Nutrition 2008;24:293-9.
- Leung AW, Chan CC, Lee AH, Lam KW. Visual analogue scale correlates of musculoskeletal fatigue. Percept Mol Skills 2004;99:235-46.
