Isoleucine amino acid by Ray Sahelian, M.D.

Isoleucine is one of the branched-chain amino acid which also include leucine and valine. I have not come across any human studies with isoleucine supplement taken orally by itself. Therefore as of August 2007, I am not sure why anyone would take an isoleucine supplement by itself.

Isoleucine in liver disease
Isoleucine infusion during "simulated" upper gastrointestinal bleeding improves liver and muscle protein synthesis in cirrhotic patients.
Hepatology. 2007 Mar;45(3):560-8. Department of Surgery, Academic Hospital, Maastricht University, Maastricht, The Netherlands.
Upper gastrointestinal (GI) bleeding in cirrhotic patients has a high incidence of mortality and morbidity. Postbleeding catabolism has been hypothesized to be partly due to the low biological value of hemoglobin, which lacks the essential amino acid isoleucine. The aims were to study the metabolic consequences of a "simulated" upper GI bleed in patients with cirrhosis of the liver and the effects of intravenous infusion of isoleucine. CONCLUSION: The present study investigated hepatic and portal drained viscera protein metabolism selectively in humans. The data show that hepatic and muscle protein synthesis is stimulated by improving the amino acid composition of the upper GI bleed by simultaneous intravenous isoleucine administration.