Comparison guide
L-ornithine or OKG?
L-ornithine is sold for fatigue, sleep and ammonia clearance; OKG pairs ornithine with alpha-ketoglutarate and comes from hospital nutrition for burns and wounds. The evidence is limited for both, so your goal and the price matter more than the form.
The options, compared
| Option | Evidence | Best for | The honest note | |
|---|---|---|---|---|
| L-Ornithine | Limited evidence | Cheaper option, thin evidence | Two small trials, with 17 and 52 participants, reported less fatigue at 2 g a day and better sleep scores at 400 mg a day, without independent replication. The strong liver-disease evidence belongs to L-ornithine L-aspartate, not these capsules. | View |
| OKG (Ornithine Alpha-Ketoglutarate) | Limited evidence | Clinical nutrition, not training | Hospital studies used 10–20 g a day, and even there the evidence is rated very uncertain. The 2–5 g label doses sold to athletes have no supporting trials. | View |
Our verdict
Neither is worth taking for performance or muscle. If you want to try ornithine for fatigue or sleep, plain L-ornithine at the trial doses is the cheaper option; leave OKG to supervised clinical nutrition. People with kidney or liver disease or urea cycle disorders should avoid both without medical advice.