Pregnant women taking supplements with the amino acid L-arginine plus vitamins are significantly less likely to develop pre-eclampsia, according to a new study in the British Medical Journal (BMJ).
Scientists wrote “supplementation during pregnancy with a medical food containing L-arginine and antioxidant vitamins reduced the incidence of pre-eclampsia in a population at high risk of the condition. Antioxidant vitamins alone did not have a protective effect for prevention of pre-eclampsia.”
Pre-eclampsia is a condition marked by abnormally high blood pressure and high protein levels in the urine.
Experts say defective synthesis of nitric oxide has been documented in pre-eclampsia as well.
L-arginine, an amino acid that helps to maintain a healthy blood flow, could “provide a source of substrate for nitric oxide synthesis during pregnancy, which could promote vasodilatation.”
Women and Infants Hospital in Providence says pre-eclampsia occurs during the second half of pregnancy in 5 to 8 percent of pregnancies.
In this study scientists defined pre-eclampsia as hypertension (systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or both) and proteinuria (>300 mg/24 hours) presenting after 20 weeks of gestation in women known to be previously normotensive.
Pregnant women between 14 and 32 weeks of gestation at high risk of pre-eclampsia who were receiving prenatal care at the Instituto Nacional de Perinatologia Isidro Espinosa de los Reyes in Mexico City between January 2001 and December 2005, participated in the study.
Two hundred twenty-two women were allocated to the placebo group, 228 received L-arginine plus antioxidant vitamins, and 222 received antioxidant vitamins alone. Researchers report the incidence of pre-eclampsia was reduced significantly (χ2=19.41; P<0.001) in women randomised to L-arginine plus antioxidant vitamins compared with placebo (absolute risk reduction 0.17 (95% confidence interval 0.12 to 0.21).
Antioxidant vitamins alone showed an observed benefit, but this effect was not statistically significant compared with placebo (χ2=3.76; P=0.052; absolute risk reduction 0.07, 0.005 to 0.15).
L-arginine plus antioxidant vitamins compared with antioxidant vitamins alone resulted in a significant effect (P=0.004; absolute risk reduction 0.09, 0.05 to 0.14).
Further study is needed to determine whether these results can be replicated and to identify whether they are conclusively due to L-arginine alone or the combination of L-arginine and antioxidant vitamins, according to researchers.