Arginine is usually synthesized by adults in amounts sufficient to maintain the body proteins, but additional dietary arginine is needed during periods of growth, as in childhood or during pregnancy, and possibly during times of stress. Arginine is present in most proteins, including meats, nuts, milk, cheese, and eggs. In particular, nuts, grains, and chocolate have a high arginine to lysine ratio. These foods have been noted to increase the frequency of Herpes simplex attacks (both cold sores and genital lesions) in patients infected with this virus. (Eating foods high in lysine, L-lysine supplementation, or both, may help treat such outbreaks; see the section on Lysine.) Arginine deficiencies can exist in human beings and may occur during times of high protein demand; with trauma, low protein intake, or malnutrition; or from excess lysine intake, which may compete with arginine. Arginine deficiency can result in hair loss, constipation, a delay in the healing of wounds, and liver disease.
Arginine has several important functions. It is essential to the metabolism of ammonia that is generated from protein breakdown. It is also needed to transport the nitrogen used in muscle metabolism. Arginine is one of the body-building amino acids and also influences several hormone functions. L-arginine has been shown to stimulate the pituitary gland to produce and secrete human growth hormone in young males, at a dose of more than 3 grams daily. Human growth hormone helps in muscle building, leading to increased muscle strength and tone, and enhances fat metabolism (increases the burning of fats), which may help with weight loss. Growth hormone in general seems to increase metabolism and energy. L-arginine has a positive effect on the immune system, mainly by stimulating thymus activity, and also helps the body heal from wounds. Some research has shown that high doses of L-arginine may increase male fertility by increasing sperm production and motility.
L-arginine has several possible uses. The most common use, in part promoted by Pearson and Shaw's book Life Extension, is as a growth hormone stimulant. Body builders supplement L-arginine along with L-ornithine for its muscle-building effects. Recent research has suggested that L-arginine and L-lysine together have a similar effect, possibly at lower dosages. L-arginine supplementation, at a dosage of 4 grams daily, has been successful in improving fertility in men by increasing low sperm count and motility. Arginine has been shown to help speed wound healing in rats, possibly as an aid to collagen formation. Other possible uses for L-arginine as seen in animals are to improve decreased liver functions, to lower cholesterol levels, and to inhibit the growth of certain tumors (it may also stimulate the growth of certain tumors).
L-arginine, available in 500 mg. capsules, is usually well tolerated in doses as high as 3–6 grams, although side effects such as diarrhea, nausea, and, rarely, ataxia (unsteadiness) may occur in some people. Dosages of less than 2 grams daily are usually handled without problems. A dosageof 3–4 grams daily is needed for the growth hormone effect. L-arginine and L-ornithine, or L-arginine and L-lysine, can be supplemented at 500–1000 mg. of each twice daily, or 1000 to 1500 mg. of each before bed. To improve male fertility, a dosage of 2 grams twice daily is suggested. Children and teenagers should avoid supplementation of L-arginine for growth stimulation or body building. People with diabetes must be careful because of arginine's effect on insulin and carbohydrate metabolism. Supplementation should not be done continuously for a long period. I suggest that it be used for two to three weeks, followed by a break of one to two weeks. A balanced amino acid supplement can also be used.