Enhanced libido

Both men and women have remarked about the way L-arginine seems to increase their libido, or desire for sex. Exclaimed one 21-year-old woman when asked about arginine, "My god, that stuff! I had to stop taking it. I was doing it with every guy that came along!" While her reaction may have been a bit extreme, some women have been reported to have given L-arginine to their husbands who had lost interest in sex and soon found a they had a re-aroused mate on their hands.

How does L-arginine work?

The prosexual effects of L-arginine are directly related to its ability to generate NO [Palmer, 1988]. NO molecules are produced on demand inside generator cells, such as the endothelial cells that line the insides of artery walls. An NO molecule is generated when an enzyme called NO synthase (NOS), which is abundant in these cells, strips away a nitrogen atom (N) from a passing L-arginine molecule and combines it with an oxygen atom (O). Since NO molecules have a very brief life span (their half-life is only about 5 seconds), their site of activity has to be very close to home. NO formed in arterial endothelial cells passes directly into immediately adjacent smooth muscle cells that surround the artery. This causes them to relax and leads to a reduction in blood pressure. A constant seepage of NO molecules is now identified as being crucial for controlling blood pressure [Anggard, 1994]. The more NO that is present, the lower the blood pressure, and vice versa. When people have hypertension (high blood pressure) because their arterial endothelial cells are damaged and cannot make NO (a common finding in cardiovascular disease), their blood pressure drops after they receive an intravenous infusion of L-arginine [Drexler, 1991]. Dr. Salvador Moncada, research director at Wellcome Research Laboratories and a leading NO investigator, points out that if you place a drop of NO on the muscles that encircle a blood vessel, they instantly relax, which allows more blood to flow through them. He calls NO a "universal transducer," which is a kind of universal biochemical interpreter that translates chemical/electrical messages from one form to another [Kolata, 1991].

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