Folic Acid and its Relationship to Birth Defect Prevention

Adequate concentrations of certain micronutrients including folic acid, thiamine, and other vitamins are necessary for the normal health and development of unborn children. Recent epidemiological studies support a role for folic acid in the prevention of a variety of birth defects. The defects include neural tube defects (NTDs), cleft lip and palate, and potentially conotruncal heart defects. NTDs encompass a variety of disorders of the developing brain and spine that include spina bifida and anencephaly. These are among the most common of all human birth defects. While periconceptional folic acid supplementation is believed to prevent up to 70 % of NTDs, the underlying mechanisms for this protective effect are presently unknown. Understanding how folic acid helps to prevent birth defects is one of the primary focuses of the laboratory of Dr. Richard Finnell, the Director of the Center for Human Molecular Genetics located in the Munroe-Meyer Institute at the University of Nebraska Medical Center.

Evidence is accumulating to suggest that birth defects are due, in part, to changes in our deoxyribonucleic acid, or DNA. Generally speaking, the physical differences between people can be accounted for by their genes, which are composed of DNA. Individuals differ slightly in their genes from one another and these small differences in genes are known as polymorphisms. Polymorphisms account for why some people have blue eyes while others have brown eye color, or why some people get certain illne

sses easier than others. Studies have shown that folic acid is compensating for a difference in how a gene or genes functions in the developing conceptus. The key to understanding how folic acid helps to prevent birth defects may be the identification of the difference in those genes.

There are two primary ways that Dr. Finnell and researchers in his laboratory are attempting to solve this scientific puzzle. One way is by analyzing the DNA of patients who suffer from selected types of birth defects, as well as their family members. Another way that the laboratory studies the role of folic acid is through the use of genetically engineered or "transgenic" laboratory mice. Genes under investigation in Dr. Finnell’s laboratory include those that either process or provide a receptor (a protein that acts like a doorway for the entry of folic acid into the cell) for folic acid. It is the long range goal of the laboratory to generate enough information about how folic acid prevents birth defects to ultimately contribute to the development of preventative strategies, since there are some women for whom folic acid is not as efficient in preventing these birth defects.

An important thing to remember, however, is that just because certain amounts of folic acid are good, it does not mean "more is better". The Food and Drug Administration has developed a set of guidelines for the level of folic acid to be used as a dietary supplement. While folic acid is believed to be a powerful means by which to help prevent birth defects, it is strongly suggested that women of reproductive age consult their physician or health care provider to learn what amount of folic acid in their diet is beneficial for them. Just to be safe, one should take a multi-vitamin containing 400 micrograms of folic acid every day.

Contributed by Richard H. Finnell, PhD, HBM Professor of Developmental Molecular Genetics, Director, Center for Human Molecular Genetics, Professor, Departments of Pediatrics, Cell Biology and Anatomy, UNMC

Date last updated: January 27, 2003