From the Manufacturer's Label:
L-Lysine is one of 9 essential amino acids that cannot be made in the body. It is the basic raw material for carnitine synthesis. L-Proline can be made in the body, but low protein/vegetarian diets may not always promote optimal -Proline production.
Manufactured by Source Naturals
Allergies: Suitable for vegetarians and HYPOALLERGENIC: contains no yeast, dairy, egg, gluten, corn, soy or wheat. Contains no sugar, starch, preservatives, or artificial color, flavor or fragrance.