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18.07.2010

Wounds heal more quickly with arginine

They've just removed the gyno from your pecs in hospital. Or you've been stupid enough to break in to the undersigned's house. Or you ripped your leg open doing a sliding tackle. Whatever, you've got an ugly wound and you want it to heal as quickly as possible. Taking L-arginine supplements may help, according to a review article by Adrian Balbur of the Sinai Hospital, Baltimore, published in the Journal of Nutrition. An increased intake of this amino acid speeds up wound healing.

Balbur is one of a group of researchers who have been researching for years whether arginine, and its metabolite ornithine, speed up wound recovery. The researchers are interested in the stimulatory effect that these amino acids have on the formation of collagen, the substance the body uses to knit wounds together.

The main component of collagen is glycine, followed in equal amounts by proline and hydroxyproline. From analyses of wound fluid, the Americans worked out that it is the amount of proline that is the limiting factor in wound healing. Attempts to speed up wound healing by using proline supplements have not been successful, however. What does work – especially in animal studies – is supplementation with the proline precursor arginine. [The scheme here shows how the body converts one amino acid into another.]

The figure below shows how strongly wounds healed in mice after they received feed containing 1 percent arginine for two weeks. On the left you see the effect on normal mice, on the right on knockout mice who have been genetically modified so that they no longer make the enzyme that converts arginine into NO.

Apparently arginine only works if it is converted into NO, you'd be forgiven for thinking. But when the researchers repeated the experiments with ornithine, they noticed that ornithine speeded up wound healing in the knockout mice.

Arginine has different pharmacological properties than ornithine, the researchers state. On top of that, ornithine is not an NO precursor. Maybe ornithine does something with growth hormone, like doctors now know that it helps wounds to heal more quickly.

Or maybe ornithine does something to the immune system.

The researchers freely admit that they are speculating. When it comes to how the amino acids work, they are groping in the dark.

Source:
J Nutr. 2008 Oct; 138(10): 2021S-2024S.