L-lysine is one of the essential amino acids you need to obtain from diet, as your body cannot produce it on its own. It is the basic raw material for carnitine synthesis. L-proline can be made in your body, but low protein or vegetarian diets may not always promote optimal L-proline production. Together, L-proline and L-lysine amino acids are the precursors of hydroxylysine (HL), and hydroxyproline (HP), two constituents of collagen. Collagen is an essential component of arterial linings. Vitamin C, a strong antioxidant, is included in this formula as it is also important for the production of healthy collagen. And finally, hawthorn berry and grape seed extract are added for their potent natural antioxidant potential that is due to their high levels of proanthocyanidin. These proanthocyanidin-esters are excellent free radical scavengers.