FUNCTIONAL FOOD

PROBLEM TO BE SOLVED: To enable a functional food for promoting the diuretic while simultaneously cleaning the blood without excessively restricting the diet to be safely and inexpensively supplied in large amount. SOLUTION: This functional food contains chondroitin sulfuric acid derived from the nasal cartilage of a salmon or a trout, and sap of a tree belonging to the genus Butula of Betulaceae. In one case, the functional food is a soft jerry shape consisting essentially of the chondroitin sulfuric acid, and in the other case, the functional food is a liquid drink consisting essentially of the sap of the tree belonging to the genus Butula of Betulaceae. The chondroitin sulfuric acid is preferably obtained by pulverizing the nasal cartilage of the salmon or the trout, removing the fat from the pulverized product, decomposing the resultant product by using an alkali, subjecting the decomposed product to oxygen treatment, and purifying and extraction-treating the oxygen treated material, and the pulverizing of the nasal cartilage of the salmon or the trout is preferably carried out under a low temperature condition of -30 to -60 deg.C.