BETHESDA, Md.--The addition of folic acid to cereal grain products, required Jan. 1, 1998, by the U.S. Food and Drug Administration (FDA), effectively increases intake of this important B vitamin in adults, according to a new study published in the December American Journal of Clinical Nutrition.
"The absorption of folic acid from fortified white and whole wheat bread, rice, and pasta, was consistently good in the seven men and seven nonpregnant women who participated in the study," said senior author Jesse F. Gregory III, Ph.D., Professor of Food Science and Human Nutrition, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, who was involved in the study with three associates. "The components of the cereal grain foods did not significantly interfere with the absorption of the added folic acid."
On January 1, 1998, U.S. manufacturers of enriched cereal grain foods are required to add folic acid at a concentration of 1.4 micrograms per gram to their products. This FDA requirement is based on a recommendation from the U.S. Public Health Service (PHS) that all women of childbearing age consume 400 micrograms of folic acid per day to reduce their chances of having a baby with a neural-tube defect (any congenital defect involving the brain and spinal cord).
"Nationwide food-consumption surveys suggest that the average daily folate intake for women of child-bearing age is 180 to 200 micrograms per day," said Dr. Gregory. "That is well below the PHS recommendation."
Another benefit of adding folic acid to cereal grain products, according to the study's senior investigator, is the possibility of reducing homocysteine concentrations in the blood of individuals, which could lessen their risk for several forms of heart disease.
The 14 study subjects, who were 20 to 35 years old, participated in 7 trials of folic acid intake. Each individual had normal blood chemistry, hematologic indexes, and serum and blood folate concentrations.
The studies with the 14 subjects were conducted using folic acid labeled with nonradioactive isotopes of carbon and hydrogen.
Of the seven trials, the first five were conducted to evaluate how well the isotope-labelled folic acid in either water (the control substance) or in the different experimentally fortified grain products was absorbed into the bloodstream. The investigators conducted the final two trials to study a liquid supplemental dose of folate consumed either with or without a light breakfast.
The research team analyzed serum and red blood cell folate concentrations of the 14 participants by microbiological assay. Also, the total folate concentration of urine was measured by high pressure liquid chromatography.
"On the basis of our findings, fortified cereal grain products appear to be highly effective as sources of bioavailable folic acid," said Dr. Gregory.
Following preparation and before serving the fortified cereal grain products, he added, the team found the retention of added folic acid in the white bread to be 70%, the wheat bread 67%, the rice 86%, and the pasta 46%.
In addition to their cereal grain findings, the researchers concluded that folic acid consumed as a vitamin supplement either without food or with a light breakfast is absorbed in a fashion similar to that noted for the cereal grains.
The folate research was sponsored by the U.S. Department of Agriculture--National Research Initiative Competitive Grants Program.
Commenting on the folic acid study for an editorial in the same issue of the monthly peer-reviewed journal of the American Society for Clinical Nutrition, Tsunenobu Tamura, M.D., Professor of Nutrition, Department of Nutrition Sciences, University of Alabama at Birmingham, said: "Considering the information available, it is reasonable to conclude that folic acid added to cereal-grain products is bioavailable to a certain extent or is close to that of folic acid supplemented alone. Therefore, certain positive benefits should be expected to lower the incidence of pregnancies affected by neural-tube defects and to possibly reduce occlusive vascular diseases by lowering plasma and serum homocysteine concentrations."
He noted: "The fortification of staple foods with folic acid may be the most practical and feasible means to increase folate intake in the population."
In the editorial, Dr. Tamura also called for a better means of determining folic acid levels required to maintain health and prevent disease, through a reevaluation of current food folate tables. To accomplish that goal, a more accurate method must be developed to determine folate availability in individual foods.
Journal
American Journal of Clinical Nutrition