Now Foods L-Proline 500 mg is a dietary supplement in capsules containing L-proline. Each capsule contains 500 mg of this valuable amino acid to support the daily diet of adults, including vegans and vegetarians. What is L-proline? Proline is an organic chemical compound from the α-amino acid group. L-proline is a natural amino acid included in plant and animal proteins. The richest dietary source of proline may be animal products, including those containing gelatin and cheese, beef, pork, and soy protein. One way to supplement your L-proline intake in your daily diet can be a dietary supplement from Now Foods. L-Proline 500 mg by Now Foods is 2-4 capsules per day. The package contains 120 vegan capsules.