URIC ACID

Uric acid is produced by xanthine oxidase from xanthine and hypoxanthine, which in turn are produced from purine. Uric acid is more toxic to tissues than either xanthine or hypoxanthine.

In humans and higher primates, uric acid is the final oxidation (breakdown) product of purine metabolism and is excreted in urine, over half the antioxidant capacity of blood plasma comes from uric acid. About 70% of daily uric acid disposal occurs via the kidneys, and in 5-25% of humans impaired renal (kidney) excretion leads to hyperuricemia.

Excess serum accumulation of uric acid can lead to a type of arthritis known as gout.

Elevated serum uric acid (hyperuricemia) can result from high intake of purine-rich foods, high fructose intake (regardless of fructose's low glycemic index (GI) value) and/or impaired excretion by the kidneys. Saturation levels of uric acid in blood may result in one form of kidney stones when the urate crystallizes in the kidney. These uric acid stones are radiolucent and so do not appear on an abdominal plain x-ray or CT scan. Their presence must be diagnosed by ultrasound for this reason. Very large stones may be detected on x-ray by their displacement of the surrounding kidney tissues. Some patients with gout eventually get uric kidney stones.

Gout can occur where serum uric acid levels are as low as 6 mg/dL (~357µmol/L), but an individual can have serum values as high as 9.6 mg/dL (~565µmol/L) and not have gout.

Sources of uric acid :
* In many instances, people have elevated uric acid levels for hereditary reasons. Diet may also be a factor; eating large amounts of sea salt can cause increased levels of uric acid. (Medical consultation is recommended before using large quantities of sea salt in daily cooking.)

* Purines are found in high amounts in animal internal organ food products, such as liver. 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.

* Examples of high purine sources include: sweetbreads, anchovies, sardines, liver, beef kidneys, brains, meat extracts (e.g. Oxo, Bovril), herring, mackerel, scallops, game meats, and gravy.

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

* Serum uric acid can be elevated due to high fructose intake, reduced excretion by the kidneys, and or high intake of dietary purine.

* Added fructose can be found in processed foods and soda beverages as sucrose, or in some countries, as high fructose corn syrup.