Folic acid is a synthetic version of vitamin B-9 folate and is rarely involved in an overdose situation. B-9 is a water-soluble vitamin, so it is regularly being excreted in the urine, which prevents elevated levels from accumulating unless dosages of 1,000 micrograms or more per day are consumed over a long period of time. There are consequences associated with taking too much folic acid, such as the development of a zinc deficiency, sleep problems, indigestion, diarrhea and the masking of a vitamin B-12 deficiency. Also, people who suffer from heart disease have a greater risk of heart attacks when overdose levels of B-9 are reached.
When vitamin B-12 is lacking in the diet and supplementation is not occurring, too much folic acid has the potential to mask this deficiency. Under the microscope, the cells affected by the B-12 deficiency will have an identical appearance to the cells affected by too much folic acid. If the B-12 imbalance goes uncorrected, damage to the nerves can occur because B-12 is an active, vital nutrient in the growth and protection of the nervous system.
Folic acid is a B vitamin that cannot be manufactured by the human body. It must be taken as a supplement or received as a byproduct from digested food. Although one can’t reach excessive B-9 levels from eating foods that naturally contain folate, too much folic acid from both supplements and foods that have been fortified with the vitamin can eventually cause an overdose.
In the United States, folic acid deficiencies were not uncommon prior to 1996, when the U.S. Food and Drug Administration mandated that the vitamin be added to cereal, flour, pasta, bread, rice, corn meal and other grains. The FDA’s goal was to cut down on neural-tube birth defects, such as spina bifida and anencephaly, and other congenital disorders by correcting folic acid deficiencies in women of childbearing age. The program is believed to have contributed to the reduction in the number of birth defects in the U.S. It is recommended that all women of childbearing age take 400 micrograms of folic acid daily, and pregnant and breastfeeding women should receive 600 micrograms per day.
Fortified foods contribute significantly to a higher daily intake of folic acid. One should consider this when calculating appropriate microgram levels, especially for women who are pregnant. These foods carry a logo on the package indicating that folic acid has been added, and the amount is listed on the nutritional value panel.