Issues in the Prevention of Spina Bifida

WITHDRAWN: Periconceptional supplementation with folate and/or multivitamins for preventing neural tube defects

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 folate or multivitamins on the prevalence of neural tube defects periconceptionally (that is before pregnancy and in the first two months of pregnancy).

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register. Date of last search: April 2001.

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 of supplementation involving 6425 women were included. The trials all addressed the question of supplementation and they were of variable quality. Periconceptional folate supplementation reduced the incidence of neural tube defects (relative risk 0.28, 95% confidence interval 0.13 to 0.58). Folate supplementation did not significantly increase miscarriage, 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 additional preventive effects when given with folate.One dissemination trial, a community randomised trial, was identified involving six communities, matched in pairs, and where 1206 women of child-bearing age were interviewed following the dissemination intervention. This showed that the provision of printed material increased the awareness of the folate/neural tube defects association by 4%, (odds ratio 1.37, 95% confidence interval 1.33 to 1.42).

AUTHORS' 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 advised of the risk of recurrence in a subsequent pregnancy and offered continuing folate supplementation. The benefits and risks of fortifying basic food stuffs, such as flour, with added folate remain unresolved.

Erythrocyte Folate Analysis: Saponin Added During Lysis of Whole Blood Can Increase Apparent Folate Concentrations, Depending on Hemolysate pH

Background: The analysis of red cell folate (RCF) depends on complete hemolysis of erythrocytes, and it is assumed that complete hemolysis is achieved by 10-fold dilution of whole blood with hypotonic solutions of 10 g/L ascorbic acid/ascorbate. This report challenges this assumption.

Methods: The conventional method of erythrocyte lysis was modified to include saponin, a known effective hemolyzing agent. The influence of saponin was determined at various lysate pHs, using the microbiological (Lactobacillus rhamnosus) folate assay. The effect of saponin during lysate preparation was subsequently compared with either the effect of 30 s of sonication or a single 1-h freeze-thaw cycle.

Results: Saponin addition was found to increase assayable RCF up to ninefold, depending on lysate pH. Sonication of lysates had no effect, and freezing-thawing lysates once did not always guarantee complete hemolysis. Lysates created with 10 g/L ascorbic acid (a historically widely used diluent) without pH adjustment produced assayable folate concentrations significantly lower than optimal.

Conclusions: A lysing agent should be incorporated into RCF assays to guarantee complete hemolysis. Ten-fold dilution of blood with 10 g/L ascorbic acid, without pH adjustment, produces lysates with pHs (pH 4.0) below the point (pH 4.7) at which hemoglobin can denature irreversibly. The optimum pH for hemolysates is ∼5.0.

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

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.

Erythrocyte folate analysis: a cause for concern?

Neural tube defects can be prevented by adequate intake of periconceptional folate, and inverse associations between folate status and cardiovascular disease and various cancers have been noted. Thus, there is renewed interest in the analysis of red cell folate (RCF) as an indicator of folate deficiency risk. Assessment of the assumptions that underpin RCF assays indicates that many are false. Published literature suggests that increased deoxy-hemoglobin (which can bind RCF electrostatically) yields more assayable folate, and increased oxy-hemoglobin (which cannot bind RCF) yields less assayable folate. It is argued that as deoxy-hemoglobin picks up oxygen and switches quaternary structure, any bound folate must, on purely theoretical grounds, become physically “trapped”. Venous blood taken for analysis is 65% to 75% saturated with oxygen, and pro-rata “trapping” will lead to serious underestimation of RCF. Hence, doubt is cast over the validity of all previous RCF values. Some strategies for accurately assessing RCF are suggested.

Myelodysplasia in adult life: the value of an outreach nursing service

In the state of South Australia, infants with myelodysplasia have been treated by early intervention since 1963, and the majority have survived. Many are now adults, leading active lives despite having severe disabilities. A pilot study confirmed that this population has a high incidence of preventable ill health because of recurrent urinary infections, renal damage, and pressure ulcers. Many of these complications can be prevented by an outreach nursing service aimed at providing education in self-care, counseling, advocacy, and other appropriate nursing interventions, thus allowing clients to avoid hospitalization and maintain their independence. The study also showed that many clients were unaware of important social benefits, the knowledge of which should promote their financial independence. The outreach nursing service is an essential part of an integrated long-term support program for adults with myelodysplasia and other forms of congenital spinal paralysis.

Panis populi--bread and public health in Australia

The 'standard loaf, 680 gm, white, supermarket-purchased' as expressed in the Consumer Price Index, is but the basic form of bread sold to the Australian public. In the public health context, three themes have been intimately associated with bread--quality control, price control and bread used as a vehicle for supplementary nutritive agents important in preventive medicine. Price control, through assizing, has been a feature of bread marketing in western communities for seven centuries; and bread remains the last item on which price control (although seldom enforced) exists in Australia. Quality control, for public health, is determined both by regulation and by the force of increasingly literate consumers, of whom women occupy the most important determinant. From the preventive medicine point of view, important themes in bread quality, such as its use to reduce laxative sales on the one hand and to reduce the demographic incidence of colonic cancer on the other, remains outside formal regulation. Australia is a relatively conservative nation in the context of nutritional additives. It was not until 1953 that the National Health and Medical Research Council approved the addition of extra B vitamins to bread. Currently, folic acid is added as a discretion to selected high-premium breakfast cereals in Australia in one attempt to reduce the incidence to neural tube defects. The addition of such ingredients to bread remains an unrealised, but potentially important aspect of preventive medicine in Australia.