Alkalization of the urine (higher pH) increases the excretion of uric acid* in the urine. Acidification of the urine (lower pH) increases blood levels of uric acid, possibly due to the rapid reabsorption of uric acid in the kidney from acid urine. These points were verified in the testing of 18 young women who were studied on acidifying diets and on alkalinizing diets.
The acid diet had more protein and less fruits and vegetables, while the alkaline diet contained more fruits and vegetables with less protein. The acid diet included more purines, the chemicals responsible for elevated uric acid (hyperuricemia). The subjects were on the diets for 5 days each, and blood and urine tests were done daily. It took three days for the subjects to reach a steady state in the urine with a pH of 5.9 on the acid diet or a pH of 6.7 on the alkaline diet. After that time, the amount of uric acid in the urine was measured as mg/day and was graphed against urine pH.
The results of the testing confirmed that an alkaline diet can reduce uric acid levels. It should be noted that on the acidic diet, the urinary excretion of uric acid was lower than expected for hyperuricemic subjects. Presumably, this was due to increased reabsorption of uric acid in the kidneys from the acidic urine.
CONCLUSION: Uric acid clearance of the blood by the kidneys is “strikingly” lower when the subject is on an acid diet than when on an alkaline diet.
NOTE: *Uric acid is a weak acid, and therefore, contributes very little to the urine pH.
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