(b) List available foods for diets used in disturbances of the liver. List the foods to be avoided in such cases. FOOTNOTE: [155] "Diet in Health and Disease," p. 399, by Friedenwald and Ruhraeh. CHAPTER XXII GOUT, OBESITY, EMACIATION Gout is a constitutional disease characterized by an inflammatory condition of the joints. It is caused by or associated with a retention of uric acid in the blood. Gout is also characterized by the deposit of uric acid or sodium salts which occurs in different parts of the body, the joints, the lobe of the ear, the knee and the elbow being common points where the deposit of these salts ordinarily occurs. The amount of uric acid is lessened in the urine in cases of true gout, except in acute attacks, and in this way it is distinguished from the so-called goutiness in which a urinalysis shows an excess of uric acid. According to Strouse, this excess of uric acid in the urine "means a physical-chemical change in the urine and is quite different from the small amount usually excreted."[156] ~Source of Uric Acid.~--In man the uric acid which is eliminated in the urine is derived from two sources. It may be taken with the body as purins in food, in which case it is spoken of as being an "exogenous" product, or it may be formed in the body from the breaking down of the nucleoproteins (the highly nucleated cells of the glandular organs particularly). When the uric acid is formed in this manner as the result of the metabolism of the body tissues, it is known as "endogenous." In the normal body approximately one-half of the uric acid formed is oxidized, while the remaining half is eliminated from the body by way of the urine. ~Elimination of Uric Acid.~--In gout such is not the case, the body loses to a certain extent the ability to eliminate the uric acid, hence it is retained within the body, causing an excess in the blood stream, and it is this excess uric acid in the blood which causes the acute attacks and general pain and discomfort which inevitably occur in chronic gout. ~Purin-bearing Foods as Sources of Uric Acid.~--Formerly no difference was made in food; all were supposed to cause uric acid formation, but with the exhaustive investigation of food materials this sweeping condemnation has been to a great extent removed or narrowed down to a few foods, those rich in purins being the chief offenders. ~Chief Causes of Gout.~--Without a doubt, overeating, overindulgence in alcoholic stimulation, lack of exercise, etc., are chiefly to blame for the large percentage of the cases, but upon investigation it will be seen that those individuals are as a rule large protein eaters and that their mode of living is not such as to assist the body in throwing off the poisons which form as the result of their self-indulgence.