Folic acid (vitamin B9) is important in a vast number of human metabolic pathways. Examples include; interconversion of amino acids serine to glycine, conversion of homocysteine to methionine, synthesis of purines and pyrimidines, growth and healthy development of a fetus. The nutritional benefits of folic acid were first discovered by Lucy Wills in 1931 but it was finally synthesized in pure form by Bob Stroksand in 1943. Unambiguous evidence has been available for more than two decades on the effectiveness of periconceptional folic acid supplementation (PFAS) in preventing neural tube defects (NTDs). However, though this information exists a large population of its target audience (the childbearing age women) remain blissfully unaware of this very important fact.
Birth defects are documented as the leading cause of infant mortality worldwide and neural tube defects are the third leading birth defects (United States Institute of Medicine [USIM], 1998). Periconceptional folic acid supplementation, the oral ingestion of folic acid supplements of not less than 0.4mg per day; from preconception period to 12 weeks post conception has been proven to reduce the risk of occurrence and 4mg per day the risk of reoccurrence of neural tube defects. Neural tube defects are series of congenital anomalies that result as a consequence of faulty or aberrant neural tube development, which has been shown to be linked to less than optimal maternal blood folate concentration. The most common NTDs are Spina bifida and anencephaly. Spina bifida is the embryologic failure of fusion of one or more vertebral arches, sub-types of Spina bifida are based on degree and pattern of deformity. Two broad types of Spina bifida are Spina bifida occulta and Spina bifida cystica. Basically, the neonate is born with an exposed spinal cord (Pitkin, 2007). Anencephaly on the other hand is a congenital defective development of the brain with absence of bones of the cranial vault and absent or rudimentary cerebral and cerebella hemispheres, brainstem and basal ganglia. This condition is almost invariably fatal.
The neural tube is the early spinal cord found in embryo’s which forms within 28 days after conception. Due to the fact that this is very early in pregnancy most NTDs develop before women realize that they are pregnant, therefore too late for them to do anything to avert it. In developed economies though, there are a number of prenatal tests that are carried out to test for NTDs especially in those perceived to be at risk. The most commonly employed test is alpha fetoprotein (AFP). This is because abnormally high levels are recorded in open NTD cases. Other tests include amniocentesis and ultrasonography, though no one testing procedure is infallible.
The link between folate deficiency and NTDs was first suggested by Hibbard (1964). Further research was reported by Smithels (1983). Since then, many other trials using folic acid supplements in pregnant women have been done all over the world. The results demonstrated conclusively the link between folate deficiency and increased risk of NTDs (Hoffbrand, 2001). Due to the early development of NTDs in fetuses, it is important that women in childbearing age increase their folate intake prior to conception as well as during the first 12 weeks of pregnancy. Both the United States Public Health Service and the British National Health Service (1992) recommend that women intending to become pregnant should take folate supplements of 0.4mg per day until the 12th week of pregnancy (Mesereau and Kilker, 2004). Research has shown that a daily folate supplement of 0.4mg reduces the chance of neural tube defects by an estimated 36%; also that 4mg per day has been estimated to prevent 8 in 10 cases of NTDs provided the supplementation is started prior to conception (Wald, 2004).
- Statement of the Problem
During pregnancy there is a marked increase in folate utilization. This is primarily as a result of increase in reactions requiring single carbon transfers, rapid rate of cell division in maternal and fetal tissues also deposition of folate in the fetus. Even though the benefits of folate to general health of the population are well documented, the current daily intake of folates among women aged 19-65 years is only 0.292mg (Butriss, 2005) a value well below the recommended daily intake (RDI) for pregnant women .The recommended daily intake for pregnant women is 0.6mg this is based on the amount that maintained erythrocyte concentrations during clinical trials (Allen, 2004).
Randomized clinical trials have shown that folic acid supplements taken prior to conception and through approximately the first twelve weeks of pregnancy lowers the risk that a genetically predisposed woman will have a baby with a neural tube defect (Hoffbrand, 2004; Taylor and May, 2008). Neural tube defects occur in approximately 0.1% of births in the United States (King, 2004). It affects 4,500 pregnancies yearly in the European Union (Tita, 2005) and approximately 0.9% of births in other countries. Neural tube defects tend to reoccur in subsequent pregnancies if aggressive periconceptional supplementation is not undertaken. Higher intake of dietary folate, and not less than 4mg daily of folic acid supplements, including higher erythrocyte folate concentrations are inversely related to the risk of neural tube defects (Weller, 1993; Shaw, Schaffer, Verlie, Morland & Haris, 1995). Clinical trials have shown that women with neural tube affected pregnancies absorb 20-25% less folate from either supplements or foods than women in the control group. The mechanism by which folate lowers the risk of NTDs is not fully understood. Presumably, women at risk have a metabolic defect that hinders folate metabolism. This affects bioavailability and impedes transport of folate and critical metabolites to the rapidly growing embryo.
Periconceptional folic acid supplementation is both simple and cost effective. This is because not only does it prevent occurrence and reoccurrence of NTDs it also ensures optimal blood folate concentration. It prevents hyperhomocystenemia (elevated blood homocysteine level) which is associated with a myriad of other health conditions. Elevated blood homocysteine has been associated with greater risk of pre-eclampsia, preterm delivery and a greater risk of low birth weight infants (Volset, 2000). A rise in incidence of abrupt placentas, spontaneous abortions and club foot were also documented. Periconceptional folic acid supplementation is very important in the case of adolescent mothers. This is because they are still growing and have increased folate needs; they easily deplete their folate stores placing both themselves and their babies at risk. Another point on its scoreboard is the fact that dietary folate is not as easily assimilated as the supplement due to reduced bioavailability.