THE INFLUENCE OF DIETARY FACTORS ON THE RISK OF URINARY STONE FORMATION

The action of various beverages and foods on the composition of the ur ine in the circadian rhythm and in the 24-hour urine has been investig ated under standardized conditions. Orange juice leads to a significan t increase of urinary pH and citric acid excretion. Black tea leads to a raised excretion of oxalic acid by only 7.9%. In the short term, be er increases diuresis, but afterwards leads to a compensatory antidiur esis with increased risk of stone formation. Depending on their compos ition, mineral waters have very different effects on the urinary const ituents. Milk as well as cocoa beverage significantly increase calcium excretion; moreover, cocoa causes an increase in the oxalic acid excr etion. The leafy vegetable foods containing oxalate, e.g., spinach and rhubarb, lead to peaks of oxalate excretion of 300-400% in the circad ian excretion curve. Cheese leads to a significant rise of calcium exc retion with acidification of the urine and lowering of citrate excreti on. Calcium excretion is increased by 30% by sodium chloride. Foods co ntaining purine result in an increased uric acid excretion over severa l days. Depending on their phytic acid content, brans bind calcium, bu t lead to an increased oxalic acid excretion. Analysis of the urine in dicates that average diet in Germany entails a high risk of urinary st one formation. As a result of the change to a balanced mixed or vegeta rian diet, according to the requirements, significant alterations in u rinary pH, calcium, magnesium, uric acid, citric acid, cystine, and gl ycosaminoglycan excretion are measured, resulting in a drastic reducti on in the risk of urinary stone formation.