Technically, proline is an imino acid. It is the only imino protineogentic acid of its type and therefore often referred to as an amino acids. For the purpose of this article, proline will be regarded as an amino acid due to its important role in protein synthesis.
L-proline is a non-essential amino acid manufactured mainly from ornithine, glutamine, and glutamate in the liver. Proline is one of the principal amino acids that are needed by the body to build collagen. This is a structural protein required to make elastic fibres found in the skin, bones, ligaments and tendons. Together with lysine and vitamin C, proline is converted into hydroxlysine and hydroxyproline to help form collagen.
L-proline and healthy skin
As the largest organ of the body maintaining healthy skin is important. Our skin is the first immune defense protecting the body from infection. Hydroxyproline is needed to synthesis collagen and helps to aid skin elasticity and thickness.
Aged skin is characteristically thinner and less fibrous due to a decline in collagen production. Combined with UV exposure and free radical damage, the skin becomes less smooth and more wrinkled. This loss of texture and structure accelerates the appearance of aged skin.
Research has found that proline supplementation, along with other key amino acids can elevate collagen production. Murakami and colleagues investigated the importance of various amino acids in restoring dermal collagen protein synthesis in mice after exposure to UV irradiation. The researchers concluded that proline along with branch-chained amino acids (BACCs) and glutamine could enhance collagen synthesis in the study animals1.
Proline has been proven to increase collagen synthesis in human fibroblast cells together with its precursors, glutamate and pyrroline-5-carboxylate2. Thus, by increasing the availability of l-proline it may be possible to slow down the aging process and enhance skin health.
L-proline and tissue repair
During times of injury where there is soft tissue damage the body elevates proline production. This helps to heal the wound. Animal studies have shown that topical administration of l-proline at the wound site can accelerate healing much faster than oral administration3, 4. Medical dressings that utilise collagen fragments to initiate wound healing also include proline.
In some cases, a deficiency in proline may be responsible for a higher susceptibility to tears or strains of soft tissues. A lack of this amino acid may also lead to slower than average healing times. For these reasons it’s often recommended to take a proline supplement following a soft tissue injury to enhance collagen production and accelerate healing.
L-proline and cardiovascular health
Hardening of the arteries, known as arteriosclerosis, is the leading cause of heart disease. This condition develops as the arteries thicken and become stiff following the accumulation of fat on the artery walls.
This restricts the transport of nutrients and oxygen throughout the body. The reduced blood flow and pressure build-up causes heart attacks.
Symptoms of a l-proline deficiency
Proline deficiencies are extremely rare. It is widely available in many different foods. People at risk of having low proline levels are typically on a protein restricted diet.
Endurance runners and people that participate in prolonged exercise routines may have a greater requirement for this amino acid. Proline helps to produce and sustain muscle tissue.
When glucose supplies decline, the body will start to cannibalise its own muscle. Boosting proline supplies can help to prevent this occurring in serious athletes.
Individuals that have experienced traumatic skin injuries or severe burns will have a higher need for proline to support tissue repair. People experiencing joint pain from insufficient collagen or cartilage formation may also need additional proline.
Dietary sources of l-proline
This amino acid is found in numerous foods and most people obtain enough for their needs through regular diets. Dairy, meat, and soy products are enriched with proline. Supplementation may be necessary for endurance athletes, or when recovering from soft tissue injuries. People wanting to enhance skin health and appearance may also consider supplementation. Proline should be taken together with vitamin C to facilitate collagen synthesis.
It’s important to check with a doctor before taking any supplements. High amino acid intake generates higher waste products and this needed to be removed by the kidneys and liver. This can be a problem if these organs are already compromised. Consequently it’s very important to follow the recommended dosages and ensure that there are no underlying health issues.
- “Murakami, H et al. (2012). Importance of amino acid composition to improve skin collagen protein synthesis rates in UV-irradiated mice. Amino Acids. Volume 42, Issue 6, (pp. 2481-9).” ↩
- “Karna E. et al. (2001). The potential mechanism for glutamine-induced collagen biosynthesis in cultured human skin fibroblasts. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. Volume 130, Issue 1, (pp. 23–32).” ↩
- “Ponrasu, T et al. (2013). Efficacy of L-proline administration on the early responses during cutaneous wound healing in rats. Amino Acids. Volume 45, Issue 1 (pp. 179-89).” ↩
- “Corsetti G et al. (2010). Topical application of dressing with amino acids improves cutaneous wound healing in aged rats. Acta Histochemica. Volume 112, Issue 5. (pp. 497-507).” ↩
- Ivanov, V et al. (2007). Anti-atherogenic effects of a mixture of ascorbic acid, lysine, proline, arginine, cysteine, and green tea phenolics in human aortic smooth muscle cells. Journal of Cardiovascular Pharmacology. Volume 49, Issue 2 (pp. 140-5).” ↩
- “Wong, A et al. (2015). The effect of multiple micronutrient supplementation on quality of life in patients with symptomatic heart failure secondary to ischemic heart disease: a prospective case series clinical study. American Journal of Cardiovascular Disease. Volume 5, Issue 3, (pp. 146-52).” ↩
- “Rath M. (1992). Reducing the risk for cardiovascular disease with nutritional supplements. Journal of Orthomolecular Medicine. Volume 7, (pp. 153–162).” ↩