The Food and Drug Administration (FDA) chose levels of 140 mg of folic acid per 100g of enriched cereal-grain products. Included in this category were breads, buns, rolls, flour, and corn-meals, rice, macaroni, spaghetti and noodles. It was later reviewed that many of these fortified folic acid products contained significantly more total folate than what was required by federal regulation. These findings raise a concern about the effects of excessive folic acid intakes.
A combination of the use of folic acid fortification, supplementation and other fortified foods may pose a risk of adverse health effects to particular target groups such as children and women in their childbearing years.
On-going surveillance about the effectiveness and safety of folic acid fortification is still underway and many questions still remain about the potential adverse effects associated with such high intakes of folic acid.
Inconsistent results have been reported concerning the effects of high folate levels on human epileptics. There have been indications of high levels of negative excitatory effects causing increases in the frequency and severity of seizures and reducing the effectiveness of anti-convulsants, while others have shown no such effects. Up to date there is no available evidence-based information about the effectiveness or dosing of folic acid supplements in womenwith epilepsy . Studies have shown no adverse effects of high oral doses of folates in animals.
However, doses exceeding 250mg/day have shown to produce epileptic responses and renal hypertrophy in rats.Current research suggests that folate may form a non-absorbable complex with Zn, thus antagonizing the utilization of that essential trace element at levels of high intake of thevitamin. Studies with animal models have not consistently shown such antagonism and most results indicate that even at high levels of intake, folate does not affect Zn status.
The most commonly cited risk of folic acid, especially in pregnancy, is the condition megaloblastic anemia, which is caused by a low folate status. In normal women on a folate-deficient diet, megaloblastic anemia develops after 15 to 18 weeks. In pregnant women this condition develops more rapidly and presents abnormalities such as a fall in erythrocyte count and an increased mean corpuscular erythrocyte volume. High doses of folate (5 mg/day oral) have been shown to correct megaloblastic anemia. However, because folate treatment does not affect the neurological lesions of the vitamin B12 deficiency, pernicious anemia, concern has been raised that random use of large folate supplements may mask and potentially aggravate the neurological consequences of a vitamin B12 deficiency in their early and more easily treated stages.
Resources:
1. Olsen BH, Keast DR, Song WO, Morris DH. Effectiveness and Safety of Folic Acid Fortification. Olson:Nutrition Today. 2004;39:169-175.
2. D’Anci KE, Rosenberg IH. Folate and Brain Function. Curr Opin ClinNutr MetabolCare. 2004;7:659-664.
