L-Ornithine May Help with Fatigue

by | Dec 11, 2008 | 2008, Amino Acids, Fitness and Exercise, Ornithine

Written by Greg Arnold, DC, CSCS. In a small human study on a bike test, those given 2000mg/day ornithine after 2 hours had 91% less fatigue scores.

Fatigue is defined as “difficulty in initiating or sustaining voluntary activities (1), and is common symptom both in sickness and in health (2). It can pose a serious risk to health through chronic fatigue syndrome (a condition characterized by a decrease in the ability to participate in ordinary activities by 50%) (3) and a condition called karoshi (death as a result of overwork). This condition was introduced 40 years ago but has increased every decade since (4).

Now a new study (5) has found that supplementation with L-Ornithine may help deal with fatigue. L-Ornithine is an a amino acid that stimulates the pituitary gland (6), thereby initiating release of growth hormones and increased metabolism of carbohydrates, proteins, and fats (7). As a result, it is thought that increasing L-Ornithine intake would help decrease fatigue.

In the study, 17 healthy men and women with an average age of 41 were given either 2000 mg per day of L-Ornithine or placebo. The subjects completed a bike test at 80% of their maximum heart rate for two hours, after which they rated their fatigue. They then took the L-Ornithine or placebo capsule and biked again for two hours. They rated their fatigue again, took the afternoon to recover (about 4 hours) and rated their fatigue once more.

By the end of the study, no significant differences were seen in blood pressure between the two groups , but both experienced increases in resting heart rate (10% increase in the L-Ornithine group and 10.3% increase in placebo group). While there was no difference in ‘fatigue feeling’ between the two groups at the end of the first two-hour bike test, after the second two-hour bike test, the fatigue score was 91% higher in the placebo group than in the L-Ornithine group. In the physical performance test, at the end of the second two-hour bike test, decreases in mean pedal speed were 130% higher in the placebo group than in the L-Ornithine group.

For the researchers, “We recommend L-ornithine intake as a nutritional supplement in cases of fatigue.”

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 December 11, 2008.

References:

  1. Chaudhuri and P.O. Behan, Fatigue in neurological disorders, Lancet 363 (2004), pp. 978–988.
  2. E. Ream and A. Richardson, Fatigue: a concept analysis, Int J Nurs Stud 33 (1996), pp. 519–529.
  3. “Chronic Fatigue Syndrome” posted on the Medline Plus website.
  4. “Karoshi-Death from overwork: Occupational health consequences of the Japanese production management” posted on the Job Stress Network website.
  5. Sugino T. L-Ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism. Nutrition Research 2008; 28(11): 738-743.
  6. Evain-Brion D. Simultaneous study of somatotrophic and corticotrophic pituitary secretions during ornithine infusion test, Clin Endocrinol 17 (1982), pp. 119–122.
  7. M.B. Davidson MB , Effect of growth hormone on carbohydrate and lipid metabolism, Endocr Rev 8 (1987), pp. 115–131.