Increased fluid intake is a common recommendation for all stone formers. Low urine volume can be the result of insufficient intake, gastrointestinal and insensible losses. While there is no agreement on the total amount of fluid that should be consumed, it is recommended to consume enough fluid to produce at least 2 L of urine daily to maintain suitably low urine uric acid supersaturation.

Uric acid is derived from two primary sources, endogenous production in the liver and dietary ingestion of purines. The dietary input to uric acid biosynthesis varies among uric acid stone formers. Because human tissues lack the enzyme uricase to metabolize purines, the end product, uric acid, must be eliminated by the gut and the kidneys. As a result of this relationship, nutrition therapy has focused on limiting foods containing purines, namely, protein from animal sources [1]. While flesh proteins such as red meats, poultry, and fish contain high amounts of purines, dairy products contain minimal purines. In uric acid stone formers with a high intake of non-dairy animal foods, nutrition therapy should be aimed at avoiding excessive intake of such foods on a daily basis. In addition, foods particularly high in purine content such as organ meats, sweetbreads (thymus and pancreas glands), fish and shellfish, beef, pork, poultry, and fowl should be limited [2].

Plant-based foods are also known to contain purines. While asparagus, cauliflower, beans, lentils, mushrooms, oatmeal, peas, and spinach are sometimes limited due to their relatively high purine content, the amount and type of purines vary as well as their bioavailability for conversion to uric acid. Plant-based purines and low fat dairy products have not been associated with increased uric acid concentration nor the risk of gout in men [3, 4]. As gout is a condition of excessive uric acid biosynthesis, these data have been used to support no limit on plant-based purine sources in uric acid stone formers.

Alcohol consumption is known to increase the serum concentration of uric acid. In addition alcoholic beverages contain purines, and beer contains a higher proportion of purines relative to other alcoholic beverages [5]. Alcohol intake has been directly related to uric acid level and the risk of gout in men; however, gout risk varied according to the type of alcoholic beverage consumed. While beer and liquor intake were both associated with risk of gout, beer consumption was linked to a higher risk of gout than liquor; wine consumption was not associated with gout risk [6]. No studies have determined the association between alcohol consumption and uric acid stone risk. Although it has not been determined whether alcohol should be restricted or one type of beverage should be recommended over another, it seems reasonable to adhere to general healthy diet recommendations to limit all types of alcoholic beverages to one per day.

Dietary intake has the potential to alter the pH of the urinary environment. Sulfate, a major determinant of daily acid load, is derived from the oxidation of sulfur-containing amino acids found in animal proteins and cereal grains. Persons consuming diets rich in animal and cereal protein excrete higher amounts of sulfate, phosphate, and uric acid compared to persons eating plant-based/vegetarian diets rich in fruits and vegetables, resulting in greater net acid excretion and more acidic urinary pH. Potassium, found in fruits and vegetables, contributes dietary base which can neutralize acid load of the diet [7].