High intakes of calcium, potassium, and fluids have been shown to be associated with lowered risk of kidney stones.
In a study published in the American Journal of Epidermiology, researchers found that consumption of beer was associated with the decreased risk of kidney stones. For each bottle of beer consumed per day, the risk of kidney stones was reduced by 40 percent.
Researchers believe alcohol suppresses the excretion of vasopressin, resulting in increased urine flow and more dilute urine. But the protective effect of beer could be mediated through water or alcohol.
Another reason why beer may also be helpful in reducing the risk of kidney stones is that the beverage may contain some other protective substances found in hops. Active components in hop extract, xanthohumol and humulone, have been shown to strongly inhibit bone resorption. These compounds could therefore slow the release of calcium from the bone and reduce calcium excretion, and therefore decrease the likelihood of kidney stones forming.
Since beer seemed to be protective against kidney stones, researchers believe the physiologic effects of other substances besides ethanol, especially those of hops, should be examined.
Source: Nutrient Intake and Use of Beverages and the Risk of Kidney Stones among Male Smokers. American Journal of Epidemiology. Vol.150, No. 2