Vitamin C and the risk of preeclampsia--results from dietary questionnaire and plasma assay.

Background: Oxidative stress plays an important role in the pathophysiology of preeclampsia.

Methods: In a case-control study of 109 women with preeclampsia and 259 controls, maternal dietary and plasma vitamin C in relation to preeclampsia risk were assessed. Dietary intake during the periconceptional period and pregnancy was ascertained using a semiquantitative food frequency questionnaire. Logistic regression procedures were used to derive odds ratios (OR) and 95% confidence intervals (CI). Plasma ascorbic acid was determined using automated enzymatic procedures.

Results: After adjusting for maternal age, parity, prepregnancy body mass index, and energy intake, women who consumed <85 mg of vitamin C daily (below the recommended dietary allowance), as compared with others, experienced a doubling in preeclampsia risk (OR = 2.1; 95% CI = 1.1-3.9). The OR for extreme quartiles of plasma ascorbic acid (<42.5 vs > or = 63.3 micromol/liter) was 2.3 (95% CI = 1.1-4.6). Compared with women in the highest quartile, those with plasma ascorbic acid <34.6 micromol/liter (lowest decile) experienced a 3.8-fold increased risk of preeclampsia (95% CI = 1.7-8.8).

Conclusions: Our results, if confirmed, would suggest that current public health efforts to increase intake of fruits and vegetables rich in vitamin C and other antioxidants may reduce the risk of preeclampsia.