Proline, a non-essential amino acid, is a signaling molecule, (a sensor of cellular energy status), that’s involved in building muscle, wound healing, , antioxidative reactions (scavange free radicals), and immune responses. Proline lowers reactive nitrogen species (ROS), therefore protecting cells against hydrogen peroxide (H2O2), tert-butyl hydroperoxide, and any carcinogenic oxidative stress inducers. (1)
Proline plus hydroxyproline are most abundant in collagen and milk proteins, and the requirements of proline for whole-body protein synthesis are the greatest among all amino acids (2)
Proline can be synthesized from the amino acids glutamine, glutamate, arginine, and ornithine.
It’s also been found that, giving 500mg/kg proline increase growth hormone and slightly lowered prolactin. (3)
Proline boosts Muscle growth
Proline has a unique cyclic structure that is involved in the folding of many proteins (protein folding is very important to create structured proteins from amino acids. These proteins are involved in many things in the body, such as eliminate toxins, muscle proteins synthesis, regulating nutrients influx and efflux in a cell), but also impedes the rate of peptide bond formation by the ribosome. (4) Ribosomes read information from the DNA, on how to create structured proteins from amino acids. The ribosome can make a mistake and create misfolded proteins, which can lead to disease.
In other works, proline guides protein folding, fiber formation and protein-protein interactions, ensuring quality protein formation with fewer mistakes (misfolded proteins).
Proline serves as a major amino acid for the synthesis of polyamines (key regulators of DNA and protein synthesis, as well as cell proliferation and differentiation) and acts in concert with arginine, glutamine, and leucine (activators of mTOR and regulators of polyamine production) to enhance protein synthesis in cells and tissues (e.g., the small intestine and skeletal muscle) (5).
Proline is an osmolyte, which helps to hydrate cells, and this hydrated state signal anabolism, where a dehydrated state signal catabolism. A more hydrated cell is also more energetic, and this energetic state has a differential stabilization effect on protein structure, stability folding, and aggregation (6, 7). Meaning, better growth. Other osmolytes include glycine, betaine, glycerol, creatine, taurine, etc…
Protein folding is influenced by the presence of intracellular osmolytes that, in turn, dramatically affect protein stabilities, protein folding rates, and protein aggregation. (8) Better hydration = greater hypertrophy.
Proline also helps to retain nitrogen. (9) You can only build muscle while in a positive nitrogen balance.
Proline helps in Joints repair
Proline is an essential component of collagen and is important for the proper functioning of joints and tendons. (10) Proline and hydroxyproline together comprise approximately 23% of the collagen molecule, which comprises approximately 30% of body proteins.
During collagen formation, proline is hydroxylated in the endoplasmic reticulum (ER) by the enzymes collagen prolyl 4-hydroxylase or prolyl 3-hydroxylase in the presence of oxygen, ascorbic acid, α-ketoglutarate, and Fe2+. For proper joint formation, you need these four co-factors.
Proline and its precursors, glutamate and pyrroline-5-carboxylate, increase collagen synthesis in human connective tissue including the skin (11) and could be used to reduce sun-induced wrinkles. (12)
Ingesting lots of proline-rich foods, such as gelatin, bone broth with lots of cartilage or milk could help you build bigger and stronger muscles and keep your joints healthy. You can’t exercise effectively with sore joints.
The strong men of old were big raw milk drinkers, and the extra proline in the milk most definitely helped them gain all that strength and size.
I advise making a shake with raw milk and egg, with some added gelatine. Don’t make it in a blender, but rather shake it in a container, or beat it with a fork.
- 500ml raw milk
- 5 raw eggs
- 2 tbsp gelatin powder
– Great lake’s gelatin – 16oz container