Pregnancy support- Vitamin Treatment

Folic Acid - updated: 24 November 2008

New standard for dietary folate intake in pregnant women

Am J Clin Nutr. 2000 May;71(5 Suppl):1304S-7S

Bailey LB.

The Institute of Medicine Panel for Folate and Other B Vitamins and Choline considered data from population-based and metabolic studies to revise the dietary intake standards for pregnancy. The recommended dietary allowance (RDA) for pregnant women is the average daily dietary intake sufficient to meet the requirements of 97-98% of pregnant women. The RDA is derived from the amount estimated to meet the requirement of half of healthy pregnant women, or the estimated average requirement (EAR). Maintenance of red cell folate was selected as the primary indicator of adequacy of folate status during pregnancy. The dietary folate equivalent (DFE) was used to interpret studies in which folate was provided as a combination of food folate and synthetic folic acid because folic acid is more bioavailable than is food folate. Many population-based studies confirmed that approximately 680 nmol (approximately 300 microg) folic acid/d consumed in conjunction with a low-folate diet prevented folate deficiency in pregnant women. Additional studies showed that 227 nmol (100 microg) folic acid/d was inadequate to maintain normal folate status in a significant percentage of the groups assessed. The EAR was derived by adding the DFE of this quantity [454 nmol (200 microg)/d] to the EAR for nonpregnant women [725 nmol (320 microg)/d] to provide an EAR of 1178 nmol (520 microg)/d. The RDA of 1362 nmol (600 microg) DFE/d was derived by multiplying the EAR by 1.2 to account for an estimated 10% CV. Data from the metabolic studies support an RDA of 1362 nmol (600 microg) DFE/d on the basis of the maintenance of normal red cell folate concentrations and agree with the findings from the population studies that 1362 nmol DFE/d is adequate to maintain normal folate status in pregnant women.

Publication Types:

• Review

Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. MRC Vitamin Study Research Group

Lancet. 1991 Jul 20;338(8760):131-7

No authors listed

A randomised double-blind prevention trial with a factorial design was conducted at 33 centres in seven countries to determine whether supplementation with folic acid (one of the vitamins in the B group) or a mixture of seven other vitamins (A,D,B1,B2,B6,C and nicotinamide) around the time of conception can prevent neural tube defects (anencephaly, spina bifida, encephalocele). A total of 1817 women at high risk of having a pregnancy with a neural tube defect, because of a previous affected pregnancy, were allocated at random to one of four groups--namely, folic acid, other vitamins, both, or neither. 1195 had a completed pregnancy in which the fetus or infant was known to have or not have a neural tube defect; 27 of these had a known neural tube defect, 6 in the folic acid groups and 21 in the two other groups, a 72% protective effect (relative risk 0.28, 95% confidence interval 0.12-0.71). The other vitamins showed no significant protective effect (relative risk 0.80, 95% Cl 0.32-1.72). There was no demonstrable harm from the folic acid supplementation, though the ability of the study to detect rare or slight adverse effects was limited. Folic acid supplementation starting before pregnancy can now be firmly recommended for all women who have had an affected pregnancy, and public health measures should be taken to ensure that the diet of all women who may bear children contains an adequate amount of folic acid.

Publication Types:

• randomised double-blind prevention trial

Periconceptional supplementation with folate and/or multivitamins for preventing neural tube defects

Cochrane Database Syst Rev. 2000;(2):CD001056

Lumley J, Watson L, Watson M, Bower C.

BACKGROUND: Neural tube defects arise during the development of the brain and spinal cord. OBJECTIVES: The objective of this review was to assess the effects of increased consumption of multivitamins or folate on the prevalence of neural tube defects before pregnancy and in the first two months of pregnancy (periconceptionally). SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing periconceptional supplementation by multivitamins with placebo, folate with placebo, or multivitamins with folate; different dosages of multivitamins or folate; prepregnancy dietary advice and counselling in primary care settings to increase the consumption of folate-rich foods, or folate-fortified foods, with standard care; increased intensity of information provision with standard public health dissemination. DATA COLLECTION AND ANALYSIS: Two reviewers assessed trial quality and extracted data. MAIN RESULTS: Four trials involving 6425 women were included. The trials all addressed the question of supplementation and they were of variable quality. No dissemination trials were identified. Periconceptional folate supplementation reduced the incidence of neural tube defects (odds ratio 0.28, 95% confidence interval 0.15 to 0.53). Folate supplementation did not significantly increase spontaneous abortion, ectopic pregnancy or stillbirth, although there was a possible increase in multiple gestation. Multivitamins alone were not associated with prevention of neural tube defects and did not produce preventive effects when given with folate. REVIEWER'S CONCLUSIONS: Periconceptional folate supplementation has a strong protective effect against neural tube defects. Information about folate should be made more widely available throughout the health and education systems. Women whose fetuses or babies have neural tube defects should be offered continuing folate supplementation. The benefits and risks of fortifying basic food stuffs, such as flour, with added folate remain unresolved.

Publication Types:

• Review

Publication Types:

• Review