What is proline?

Proline is a conditionally essential amino acid, which can be produced in your body from another amino acid glutamic acid, but in certain circumstances, such as young age or heavy illness, you may need to obtain additional amounts from foods in order to be healthy [1].

Proline in foods is incorporated into proteins.

Proline abbreviation (symbol): Pro

Proline Functions in the Human Body

Proline is:

  • A building block of the protein collagen in tendons, bones, cartilage and skin, and of other proteins [2]
  • A glucogenic amino acid, which can be converted into glucose [3]

Proline Supplements

Nonprescription (over-the-counter) oral L-proline supplements are available.

Proline Health Benefits

Proline supplements are POSSIBLY EFFECTIVE in improving symptoms of the inherited metabolic disorder ornithine aminotransferase deficiency [6].

There appears to be NO EVIDENCE about the effectiveness of proline supplements in improving bone, joint, tendons, vessels or skin health.

Proline Side Effects

For eventual proline supplements side effects read the product’s information leaflet.


Hyperprolinemia type I and II are rare inherited (autosomal recessive) disorders in which the amino acid proline accumulates in the blood due to a lack of the enzymes that break down proline [4].

The disorder is present at birth [4]. Often there are no symptoms, but mild mental retardation, seizures or schizophrenia may develop, especially in hyperprolinemia type II. Blood levels of proline can be 10-15 times higher than normal [4]. Currently, no specific treatment is available; low-protein diet usually does not help [5].

Hyperprolinemia can also occur as a complication of high blood lactic acid levels [4].

  1. Dietary Reference Intakes for Ene♦rgy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) ( 2005 ) /10 Protein and Amino Acids  National Academic Press
  2. L-proline  PubChem
  3. Amino acid  ChemPep
  4. Hyperprolinemia  Genetics Home Reference
  5. Hyperprolinemia type I  NORD
  6. van Vliet D et al, 2014, Single amino acid supplementation in aminoacidopathies: a systematic review  PubMed Central

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