Food sources of folacin
The presence of this group of factors in green leaves was the basis for the name folacin. In addition to their presence in green leaves, these factors are found in liver, meats and fish, nuts, legumes, and whole grains.
The availability of folacin from foodstuffs varies. In one study the percentage of folate absorbed ranged from 92% for frozen lima beans to 25% in lettuce. Only 31% of the folate in orange juice was absorbed compared to 82% from bananas. A mean availability of about 500/0 was found in a recent study of several common foods.
Many of the folates in food are easily destroyed by storing, cooking, and other processing. Because of the destruction offolic acid activity in dried milk, it has been suggested that ascorbic acid be added as a preservative to the milk before processing.The protective effect of ascorbic acid against folate destruction in cow's milk during boiling has been reported recently. When pasteurized milk was boiled for 1 minute, two-thirds oftotal folate was destroyed this was prevented by addition of 1 mg per milliliter of ascorbic acid. Evidence was presented to indicate that the lower blood folacin levels seen in infants who were fed cow's milk formulas compared to breast-fed infants are due to destruction of folate during formula preparation.
