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.

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.

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.¹

The presence of arginine is needed to produce ornithine in the body, so higher levels of this amino acid should increase ornithine production.

Gastrointestinal distress has been reported with intakes over 10 grams of ornithine per day.