NEW YORK (Reuters Health) – Vitamin C and E supplementation does not reduce adverse outcomes related to gestational hypertension, according to a study in the April 8th New England Journal of Medicine.

But “these results have absolutely no relevance to the use of standard doses of vitamins C and E as part of prenatal vitamins, and benefits of prenatal vitamins are not contraindicated by these findings at all,” lead author Dr. James M. Roberts told Reuters Health during a conference call.

He noted that the doses used in the study were about 10 times higher than those in prenatal vitamins. At these levels, ascorbic acid and RRR-alpha-tocopherol acetate “act as drugs rather than vitamins,” he added.

Research has suggested that oxidative stress from reduced placental perfusion causes preeclampsia. Dr. Roberts, from the University of Pittsburgh, and his co-authors note that only one of several published trials has supported a role for antioxidant supplementation in preventing the syndrome.

Their multicenter trial included 9969 nulliparous women at low risk for preeclampsia. The researchers randomly assigned the women to receive daily supplementation with vitamin C (ascorbic acid) 1000 mg and vitamin E (RRR-alpha-tocopherol acetate) 400 IU, or placebo, starting between the 9th and 16th weeks of pregnancy.

The vitamin and placebo groups had similar rates of the primary outcome (6.1% v 5.7%, respectively) – a composite of pregnancy-associated hypertension and serious adverse outcomes in the mother or baby.

There was also no significant difference in the rate of preeclampsia (7.2% vs 6.7%, respectively).

Results were no different in subgroups of women who started treatment before or after 13 weeks.

Dr. Roberts pointed out that this is the largest trial, starting at the earliest point in pregnancy, to examine the effects of antioxidant vitamins on gestational hypertension.

Its findings “provide no support for the use of vitamin C and E supplementation in pregnancy to reduce the risk of preeclampsia or its complications,” the study team concludes.

Nevertheless, “it’s still important to have a well balanced diet during pregnancy and to take prenatal vitamins,” Dr. Roberts added.

Reference:
N Engl J Med 2010;362:1282-1291.