Proline and hydroxyproline metabolism: implications for animal and human nutrition.
Study Goal
The researchers aimed to determine the physiological importance of proline and hydroxyproline in protein synthesis, growth, and metabolic functions, particularly in neonates, birds, and fish.
Results Summary
The study found that dietary supplementation with proline and hydroxyproline improved growth rates, feed efficiency, and reduced plasma urea levels in young pigs, chickens, and salmon, indicating their functional role in health and development.
Population
Young pigs (as a model for infant nutrition), chickens, and salmon.
Effective Dosage
Proline: 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1%; Hydroxyproline: 0.07, 0.14, and 0.28%.
Duration
Not specified.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
supplementing 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1% proline to a proline-free chemically defined diet containing 0.48% arginine and 2% glutamate | increase | daily growth rate | young pigs (a widely used animal model for studying infant nutrition) | - | dose dependently improved | #1 |
supplementing 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1% proline to a proline-free chemically defined diet containing 0.48% arginine and 2% glutamate | increase | feed efficiency | young pigs (a widely used animal model for studying infant nutrition) | - | dose dependently improved | #2 |
supplementing 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1% proline to a proline-free chemically defined diet containing 0.48% arginine and 2% glutamate | decrease | concentrations of urea in plasma | young pigs (a widely used animal model for studying infant nutrition) | - | reducing | #3 |
at least 0.8% proline in the diet | increase | growth performance | chickens | - | maximal growth performance depended on | #4 |
dietary supplementation with 0.07, 0.14, and 0.28% hydroxyproline (a metabolite of proline) to a plant protein-based diet | increase | weight gains | salmon | - | enhanced | #5 |
Proline plays important roles in protein synthesis and structure, metabolism (particularly the synthesis of arginine, polyamines, and glutamate via pyrroline-5-carboxylate), and nutrition, as well as wound healing, antioxidative reactions, and immune responses. On a per-gram basis, proline plus hydroxyproline are most abundant in collagen and milk proteins, and requirements of proline for whole-body protein synthesis are the greatest among all amino acids. Therefore, physiological needs for proline are particularly high during the life cycle. While most mammals (including humans and pigs) can synthesize proline from arginine and glutamine/glutamate, rates of endogenous synthesis are inadequate for neonates, birds, and fish. Thus, work with young pigs (a widely used animal model for studying infant nutrition) has shown that supplementing 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1% proline to a proline-free chemically defined diet containing 0.48% arginine and 2% glutamate dose dependently improved daily growth rate and feed efficiency while reducing concentrations of urea in plasma. Additionally, maximal growth performance of chickens depended on at least 0.8% proline in the diet. Likewise, dietary supplementation with 0.07, 0.14, and 0.28% hydroxyproline (a metabolite of proline) to a plant protein-based diet enhanced weight gains of salmon. Based on its regulatory roles in cellular biochemistry, proline can be considered as a functional amino acid for mammalian, avian, and aquatic species. Further research is warranted to develop effective strategies of dietary supplementation with proline or hydroxyproline to benefit health, growth, and development of animals and humans.