Arginine

A diet high in arginine, or exogenous supplementation with arginine or citrulline can elevate arginine levels.

Levels might also be elevated in manganese (Mn) insufficiency since Mn is a necessary cofactor in the conversion of arginine to ornithine (and urea) in the urea cycle.

Lastly, there is some literature to suggest that vitamin B6 supplementation alters plasma amino acids resulting in increased arginine.

A low protein diet, gastrointestinal dysfunction, and increased amino acid utilization in acute phases of critical illness can all contribute to deficient arginine. However, some chronic conditions, such as type 2 diabetes, are characterized by an increase in the enzyme arginase, which can subsequently result in plasma arginine deficiency. Clinically, arginine deficiency has been shown to contribute to increased susceptibility to infection, pulmonary hypertension, atherosclerosis, and impaired anti-tumor response.

Arginine is found in all protein foods and is very abundant in seeds and nuts. It is considered a semi-essential amino acid during early development, infection/inflammation, or renal and/or intestinal impairment. It has many functions in the body including:

- ammonia disposal in the urea cycle

- immune function

- stimulation of insulin release

- muscle metabolism (creatine/creatinine precursor)

- nitric oxide (NO) formation

- glutamic acid and proline formation

- glucose/glycogen conversion

- stimulation of the release of growth hormone, vasopressin, and prolactin

- wound healing

Because arginine is a precursor for nitric oxide synthesis, it is often used therapeutically in cardiovascular disease for its vasodilatory effects.