User:Una Smith/Dietary purine

A dietary purine is a purine molecule obtained from food and drink rather than from metabolic synthesis. Purine is a building block of all life on Earth, and in humans purine varies from mostly dietary to mostly synthesized, depending on the amount of purine available in the diet. Because of this, and because different foodstuffs have different concentrations of purine, some human medical conditions involving too much or too little purine have the potential to be controlled by means of a selective diet.

Excess purine in the blood serum is broken down into uric acid. Excess uric acid contributes to several medical conditions, most of which are diseases of affluence.

Common medical conditions in which purine plays an important role involve abnormal concentrations of uric acid in the blood or urine. Blood plasma concentrations of uric acid can be too low (hypouricemia) or too high (hyperuricemia). An abnormally low concentration of uric acid in the urine is not problematic in and of itself, although it may be a medical sign of a problem. In contrast, abnormally high concentrations (hyperuricosuria) may have severe complications (see Hyperuricosuria). Related conditions include gout and the minority of kidney stones that are due to uric acid (uric acid nephrolithiasis).

Individualized selective diet is beneficial in patients with idiopathic first kidney stones of uric acid type.

Myths
Purine is not found mostly in protein; a low purine diet need not be a low protein diet.

Some alcohol (beer, spirits somewhat, wine not at all) increases the risk of gout, but the risk due to beer is far above the expected risk due to its purine content. So there may be some factor other than purine involved.

Biology
Uric acid is a breakdown product of DNA and RNA.

High purine foods
Purines are found in high concentration in meat and meat products, especially metabolically active internal organs such as liver and kidney. A plant based diet generally is low in purines.

Examples of high purine sources include: sweetbreads, anchovies, sardines, liver, beef, kidneys, brains, meat extracts, herring, mackerel, scallops, game meats, and gravy.

A moderate amount of purine is also contained in beef, pork, poultry, fish and seafood, asparagus, cauliflower, spinach, mushrooms, green peas, lentils, dried peas, beans, oatmeal, wheat bran and wheat germ.

Moderate intake of purine-containing food is not associated with an increased risk of gout.

Low purine foods
Vegetarian diet has been found to result in mean serum uric acid values as low as 239 micromol/L (2.7 mg/dL). Although a vegetarian diet is typically seen as beneficial with respect to conditions such as gout, abnormally low serum uric acid (hypouricemia) may require correction.