Homocysteine and Folate Levels as Risk Factors for Recurrent Early Pregnancy Loss:

Is Supplementation with Micronutrients Still Necessary during Pregnancy? A Review

INTRODUCTION

Proper nutrition during pregnancy is important to prevent nutritional imbalances that interfere with pregnancy. Micronutrients play critical roles in embryogenesis, fetal growth, and maternal health, as energy, protein, vitamin, and mineral needs can increase during pregnancy. Increased needs can be met by increasing the intake of dietary micronutrients. Severe micronutrient deficiency or excess during pregnancy can have negative effects on fetal growth (intrauterine growth retardation, low birth weight, or congenital malformations) and pregnancy development (pre-eclampsia or gestational diabetes). We investigate whether it is necessary to continue micronutrient supplementation during pregnancy to improve women's health in this stage and whether this supplementation could prevent and control pathologies associated with pregnancy.

AIM

The present review aims to summarize evidence on the effects of nutritional deficiencies on maternal and newborn morbidity.

METHODS

This aim is addressed by critically reviewing results from published studies on supplementation with different nutrients during pregnancy. For this, major scientific databases, scientific texts, and official webpages have been consulted. PubMed searches using the terms "pregnancy" OR "maternal-fetal health" AND "vitamins" OR "minerals" OR "supplementation" AND "requirement" OR "deficiency nutrients" were performed.

RESULTS

There are accepted interventions during pregnancy, such as folic acid supplementation to prevent congenital neural tube defects, potassium iodide supplementation to correct neurodevelopment, and oral iron supplementation during the second half of pregnancy to reduce the risk of maternal anemia and iron deficiency. A number of micronutrients have also been associated with pre-eclampsia, gestational diabetes mellitus, and nausea and vomiting in pregnancy. In general, experimental studies are necessary to demonstrate the benefits of supplementation with different micronutrients and to adjust the recommended daily doses and the recommended periconceptional nutrition for mothers.

CONCLUSIONS

Presently, there is evidence of the benefits of micronutrient supplementation in perinatal results, but indiscriminate use is discouraged due to the fact that the side effects of excessive doses are not known. Evidence supports the idea that micronutrient deficiencies negatively affect maternal health and the outcome of pregnancy. No single micronutrient is responsible for the adverse effects; thus, supplementing or correcting one deficiency will not be very effective while other deficiencies exist.

Maternal homocysteine and folate levels and risk of recurrent spontaneous abortion: A meta-analysis of observational studies

AIM

The aim of the study was to review and summarize the epidemiologic evidence on the associations of homocysteine (HCY) and folate with the risk of recurrent spontaneous abortion (RSA).

METHODS

This review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. PubMed, Google Scholar, Cochrane Libraries and Chinese databases were searched through May 2019 to identify studies that met prestated inclusion criteria. Either a fixed- or a random-effects model was used to calculate the combined standardized mean difference (SMD) and 95% confidence intervals (CI).

RESULTS

Twenty-three studies involving 2052 RSA cases and 1476 healthy controls were included. Overall, women with RSA compared with those without RSA were at a significantly higher level of HCY both in plasma (SMD = 1.34; 95% CI: 0.76-1.93) and in serum (SMD = 1.46; 95% CI: 1.02-1.91), but lower level of folate both in serum (SMD = -1.63; 95% CI: -2.51 to -0.75) and in red blood cells (SMD = -1.30; 95% CI: -1.76 to -0.85). However, a statistically significant association between plasma folate and risk of RSA was not been observed (SMD = -0.82; 95% CI: -1.73 to 0.09). These findings have to be viewed with caution for the significant heterogeneity (I2: from 88 to 98%).

CONCLUSION

High HCY levels in both plasma and serum as well as low folate levels in serum and red blood cells are significantly associated with risk of RSA, which indicates that measures to reduce HCY levels or folate supplementation may help to reduce the risk of RSA. However, prospective studies are needed to confirm our findings.

Nutritional Intake and Status of Cobalamin and Folate among Non-Pregnant Women of Reproductive Age in Bhaktapur, Nepal

Cobalamin and folate are especially important for women of childbearing age due to their ubiquitous role in fetal growth and development. Population-based data on cobalamin and folate status are lacking from Nepal, where diets are mostly vegetarian. The objectives of the study were to investigate cobalamin and folate intake and status, and to explore associations with socio-demographics, anthropometrics, anemia, and dietary habits. Following a random selection of geographical clusters, we collected blood samples from 500 non-pregnant women and 24-h dietary recalls and food frequency questionnaires from a subsample of 379 women. Twenty percent of the women did not consume any food containing cobalamin during the days recalled, and in 72% nutritional cobalamin intake was <1 μg/day. Eighty-four percent of the women had cobalamin intake lower than the estimated average requirement (EAR) (<2 μg/day). In contrast, only 12% of the women had a folate intake less than 100 μg per day, whereas 62% had intake between 100 and 320 μg. Low plasma cobalamin (<150 pmol/L) was found in 42% of the women, most of whom (88%) also had elevated levels of methylmalonic acid. Our results indicated a high prevalence of nutritional cobalamin deficiency, while folate deficiency was uncommon.

Nutritional genomics

The integration of genomics into nutritional sciences has illuminated the complexity of genome responses to nutritional exposures while offering opportunities to increase the effectiveness of nutritional interventions, both clinical and population based. Nutrients elicit multiple physiological responses that affect genome stability, imprinting, expression, and viability. These effects confer both health benefits and risks, some of which may not become apparent until later in life. Nutritional genomics challenges us to understand the reciprocal and complex interactions among the human genome and dietary components in normal physiology and pathophysiology. Understanding these interactions will refine current definitions of benefit and risk and lead to the establishment of dietary recommendations that have a high predictive value, minimize the risk of unintended consequences, and account for the modifying effects of human genetic variation. Furthermore, nutritional genomics will enable the design of effective dietary regimens for the prevention and management of complex chronic disease. This review focuses on new perspectives that have been presented to the nutritional sciences by the advent of genomics, and new challenges that demand attention because of their potential impact on, and immediate translation into, current public health nutrition recommendations and interventions.