L-Arginine Beneficial for Preeclampsia

Sixty-one pregnant women with preeclampsia (mean gestational age, 29 weeks) were randomly assigned to receive, in double-blind fashion, L-arginine (1 g three times per day) or placebo until delivery, in addition to conventional therapy (intravenous magnesium sulfate, antihypertensive medications, and glucocorticoids).

The mean time until delivery was 36 days in the L­arginine group and 25 days in the placebo group (p < 0.006). The mean duration of pregnancy was 36.0 weeks in the L-arginine group and 34.8 weeks in the placebo group (p = 0.14). The dose of antihypertensive drugs could be reduced in 50% of the patients in the L-arginine group and in 13% of those in the placebo group (p < 0.05). The incidence of intrauterine growth retardation was 23.3% in the L-arginine group and 45.2% in the placebo group (p < 0.04). The mean Apgar scores at one and five minutes were significantly greater in the L-arginine group than in the placebo group.

Comment by Alan Gaby, M.D.:

The results of this study indicate that the addition of L-arginine to standard therapy prolonged pregnancy in women with preeclampsia, allowed for the use of lower doses of antihypertensive medication, and improved neonatal outcomes. As a precursor to nitric oxide, L-arginine functions as a vasodilator, which may explain its antihypertensive action in this study. The amount of L-arginine used was relatively low, considering that a typical diet provides at least 5 g/day of this amino acid. Anecdotal reports that consuming a high-protein diet can prevent preeclampsia might be explained in part by the high arginine content of such a diet. Additional research is needed to confirm the safety of L-arginine supplementation during pregnancy.

Source: Rytlewski K, et al. Effects of oral L-arginine on the fetal condition and neonatal outcome in preeclampsia: a preliminary report. Basic CIin Pharmacol Toxicol. 2006;99:146-152.

Reprinted with exclusive permission from The Townsend Letter, October 2007.

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