Ornithine
"Ornithine, an amino acid, is manufactured by the body when another amino acid, arginine, is metabolized during the production of urea (a constituent of urine)."
"As with amino acids in general, ornithine is predominantly found in meat, fish, dairy, and eggs. Western diets typically provide 5 grams per day. The body also produces ornithine."
Liver cirrhosis (hepatic encephalopathy) (L-ornithine-L-aspartate) Recovery from illness (ornithine alpha-ketoglutarate) Athletic performance (for body composition and strength)
"Since ornithine is produced by the body, a deficiency of this nonessential amino acid is unlikely, though depletion can occur during growth or pregnancy, and after severe trauma or malnutrition."
"Most people would not benefit from ornithine supplementation. In human research involving ornithine, 5–10 grams are typically used per day, sometimes combined with arginine."
"No side effects have been reported with the use of ornithine, except for gastrointestinal distress with intakes over 10 grams per day. The presence of arginine is needed to produce ornithine in the body, so higher levels of this amino acid should increase ornithine production. At the time of writing, there were no well-known drug interactions with ornithine."