THE INTAKE OF FOLIC-ACID BY WAY OF THE TOTAL DAILY DIET - INFLUENCE OF FOOD PREPARATION ON ITS FOLIC-ACID CONTENT

The folic acid content of total daily diet was determined by means of high-performance liquid chromatography (HPLC). The contents of tetrahydrofolic acid (THF), 5-methyl-THF and 5-formyl-THF were differentiated. The mean of the folic acid content of the total daily diet samples determined analytically was 205+/-60 mu g and the mean of the individual ingredients of the samples was 401+/-78 mu g, which implies that about 50% of folic acid is destroyed by common household food preparation methods. Lf the contents of pteroylglutamic acid (PteGlu) and 10-formyl-PteGlu (which cannot be determined analytically) are added, it can be assumed that the folic acid content will only be reduced by about 40%. THF and 5-methyl-THF proved to be less stable than 5-formyl-THF. The monoglutamate portion of the total folat content was higher in the total diet samples than in the individual foodstuffs as a consequence of the action of the enzym ''deconjugase'' which is released when the matrix of foodstuffs is destroyed.