Inadequate folate during pregnancy has long been associated with anemia in pregnancy and reduced fetal growth. Only during the last few decades, however, has the broad spectrum of effects of folate been recognized. Discoveries of the multiple effects of inadequate folate intake on the development of congenital abnormalities and clinical complications of pregnancy represent some of the most important advances in our knowledge about nutrition and pregnancy.
Folate background
The term folate encompasses all compound that have the properties of folic acid and include Mono glutamate forms of the vitamins. The mono glutamate form of folate is represented primarily by folic acid, a synthetic form of folate used in fortified foods and supplements. A similar mono glutamate form of folate naturally occurs in a few foods. Food sources of folate contain primarily the polyglutamates as folic acid and the polyglutamates as dietary folate.
Bioavailability of folic acid and dietary folate differs substantially. Folic acid is 100 percent bioavailable if taken in a supplement on an empty stomach and 8.5 percent available if consumed with food or in fortified food. Naturally occurring folates are 50 percent bioavailable on average. Folate requirement increases dramatically during pregnancy due to extensive organ and tissue growth that take place.
Functions of folate
Folate is a methyl group donor and enzyme cofactor in metabolic reactions involved in the replication of DNA, gene expression and amino acid metabolism. Deficiencies of folate impairs these processes, leading to abnormal cell division and tissue formation. Folate serve as methyl donor in the conversion of homocysteine to the amino acid methionine. The conversion of homocysteine to methionine depends primarily on three enzymes and folate, vitamin B12 and vitamin B6 cofactors.
A common gene variant that codes the formation of the enzyme, 5,10 methylene tetrahydrofolate reductases has been identified. This gene variant is associated with a reduction in blood folate concentration is found in 1.2 percent of non-Hispanic blacks. The prevalence of genes variants affecting folate metabolism varies within countries among population groups.
Folate and congenital abnormalities
Researchers found that Low and High intake of certain vitamins and minerals cause congenital abnormalities in laboratory animals. They have also known that neural tube defects, brain and heart defects and cleft palate can be caused by feeding pregnant rats' folate deficient. Firmly held beliefs that only severe malnutrition affects fetal growth and genetic errors are the sole cause of congenital abnormalities delayed recognition of the importance of folate to human pregnancy.
Neural tube defects are malformations of the spinal cord and brain. There are three major types of neural tube defects:
1. Spina bifida is marked by the spinal cord failing to close, leaving a gap where spinal cords collect during pregnancy. Paralysis below the gap in the spinal cord occurs in severe cases.
2. Anencephaly is the absence of the brain or spinal cord.
3. Encephalocele is characterized by the protrusion of the brain through the skull.
It is now well accepted that inadequate availability of folate between 21and 27 days after conception embryo is only 2 - 3 mm in length can interrupt normal cell differentiation and cause NTDs. Neural tube defects are among the most common type of congenital abnormalities identified in infants, with approximate 4000 pregnancies affected each year in the United States.
Dietary sources of folate
Many vegetables and fruits are good source of folate.
Adequacy of folic acid intake before and during pregnancy can be estimated by adding up the amount of folic acid in fruits typically consumed in the daily diet.
Whole grains products including bread and pastas, corn flour, brown rice, oatmeal and organic grain products may or may not be fortified with folic acid. You have to find out food labels for that.
Recommended intake of folate
Due to variation in folate intake bioavailability, the DRI for folate takes into consideration a measure called dietary folate equipment's.
Folic acid taken in a supplement without food provides twice the dietary folate equivalents as does an equivalent amount of folate from food.
It is recommended that women consume 600 mcg of folate per day during pregnancy and include 400 mcg folic acid from fortified foods and supplements. The remaining 200 mcg should be obtained from vegetables and fruits. These nutrients dense foods provide an average of 40 mcg of folate per serving, because NTDs develop before women may realize they are pregnant, adequate folate should be consumed several months prior to, as well as throughout pregnancy.
Women who have previously delivered an infant affected by an NTD have been urged to take sufficient folic acid in a supplement to reduce the risk of reoccurrence.
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