Can arginine and ornithine support gut functions?

Area of Science:

• Nutrition Science
• Gastroenterology
• Metabolic Research

Background:

• Arginine and ornithine are vital precursors for nitric oxide and polyamines, respectively, influencing gut permeability and adaptive responses.
• Dietary arginine is largely metabolized by the liver; however, the gut converts arginine to citrulline, which bypasses hepatic metabolism and is re-synthesized to arginine in the kidney.
• Ornithine supplementation, particularly as ornithine alpha-ketoglutarate (OKG), can serve as an arginine precursor, with potential benefits observed in growth hormone and insulin secretion.

Purpose of the Study:

• To examine the specific effects of arginine and ornithine alpha-ketoglutarate (OKG) on gut health.
• To investigate the potential benefits of enteral diet supplementation with arginine or OKG on mucosal barrier function.
• To understand the dual role of nitric oxide generation from arginine in conditions like sepsis.

Main Methods:

• Review of existing literature on arginine and ornithine metabolism in the gut.
• Analysis of studies investigating ornithine alpha-ketoglutarate (OKG) effects on gut morphology and polyamine secretion.
• Evaluation of research on nitric oxide production from arginine and its impact on sepsis models.

Main Results:

• Arginine and ornithine are crucial for gut adaptive responses, with gut conversion of arginine to citrulline facilitating its systemic availability.
• Ornithine alpha-ketoglutarate (OKG) administration in animal models showed potential for improved gut morphology, possibly via polyamine secretion.
• Arginine's role in nitric oxide generation is dose-dependent, with high doses exacerbating sepsis effects while low doses improved survival.

Conclusions:

• Enteral diet supplementation with arginine or OKG warrants urgent investigation for potential benefits on gut mucosal barrier function.
• The interplay between arginine, ornithine, nitric oxide, and polyamines is critical for gut health, especially in metabolic stress conditions.
• Further research is needed to elucidate the precise mechanisms and optimal application of these amino acids in clinical settings.