Proline is one of the non-essential amino acids. The body can make proline on its own, but it is also consumed in the diet. A typical diet contains about 5 grams of proline daily. The primary sources are protein-rich foods including meat, fish, and dairy. 
Proline can also be taken as a supplement, one of its important function is the production of collagen or connective tissues in the body.  In sport nutrition, it help support muscle health and injury recovery as well as healthy skin.

• Appearance: White to off-white crystalline powder.
• Solubility: Soluble in water.