:Proline & Hydroxyproline:

Function: Collagen components.

Proline and hydroxyproline are nonessential amino acids that are concentrated throughout the body, except in cerebrospinal fluid. Collagen is an important structural protein, and the major reservoir of these amino acids. Proline can be synthesized in the body from either ornithine or glutamic acid; it can be broken down into ornithine and thereby reduce the body's requirements for ornithine and arginine.

Excess proline due to genetic errors can lead to convulsions, elevated blood calcium and osteoporosis. Dietary restriction is a useful treatment, probably because the body depends on dietary proline to meet some of its proline needs. Therefore proline deficiency probably can occur under some conditions. At least one patient with Parkinson's disease with low blood levels of proline has been identified at the Brain Bio Center.

Elevated proline levels can occur in alcoholics with cirrhosis and probably in depression and seizure disorders. We have observed elevated hydroxyproline levels in cases of psychotic depression. These patients also may require extra vitamin C.

Proline is modified in smokers and becomes a carcinogen. Drugs which inhibit proline metabolism have anticancer properties. Low proline diets may be useful in some forms of cancer treatment.

Proline also may be of value in wound healing. Proline peptides are involved in important neurological proteins.

Knowledge of proline supplementation is limited. Proline is concentrated in high protein foods like meat, cottage cheese and wheat germ. There is more proline in dairy protein than in meat protein, whereas for most other amino acids, the reverse is true.