L-proline is a non-essential amino acid which is a precursor to arginine. L-arginine helps synthesis of nitric oxide (1), this in turn helps to lower blood pressure (2) and risk of coronary heart disease (3).
1 – Palmer, R. M., Ashton, D. S., & Moncada, S. (1988). Vascular endothelial cells synthesize nitric oxide from L-arginine. Nature, 333(6174), 664-666.
2 – Rees, D. D., Palmer, R. M., & Moncada, S. (1989). Role of endothelium-derived nitric oxide in the regulation of blood pressure. Proceedings of the National Academy of Sciences, 86(9), 3375-3378.
3 – Riddell, D. R., Graham, A., & Owen, J. S. (1997). Apolipoprotein E inhibits platelet aggregation through the l-arginine: nitric oxide pathway Implications for vascular disease. Journal of Biological Chemistry, 272(1), 89-95.