What Are Purines?

Purines are compounds that include adenine, guanine, hypoxanthine, xanthine, and caffeine. The first four purines, in combination with pyramidines, make up the genetic codes DNA and RNA, and energy molecules,  such as ATP, GTP and coenzyme A. They are essential for life and are found in all plant and animal cells.

How Purine Rich Diet Causes Gout

Purine metabolism, to be specific their break-down, in the liver, produces uric acid. Uric acid is an antioxidant and has beneficial effects, such as as a free-radical scavenger. When it accumulates to a high level in the blood, however, it can cause gout and other health problems.

Gout is a form of arthritis caused due to accumulation of uric acid crystals in joints, especially in the big toe.

A 12-year study that followed eating habits and gout incidence in a large number of men found that eating food rich in purine, such as meat and seafood, was associated with high risk of gout. Whereas higher level of consumption of dairy products, especially skimmed types, was associated with a reduced risk of gout. Moderate intake of purine-rich vegetables or protein was not associated with an elevated risk of gout. A recent study also found a positive association between fractose, a type of sugar, and sweetened beverages and gout.

According to some studies, a purine-free diet decreases blood uric acid level, on average, from 1.0 to 1.2 mg/100 ml; whereas, consumption of 4 g of ribonucleic acid (RNA), purine,  per day, increases blood uric acid level from 1.5 to 2.0 mg /100 ml.

Recommended Daily Intake of Purines

The Dietary Guidelines for Americans has no recommended daily intake for purines. In Japan, to prevent an abnormal high level of uric acid in blood and gout, it is recommended to keep purine consumption to under 400mg per day.

Foods High or Low in Purines

In the following tables are estimates of purine content in a variety of food items, presented in descending order. Meat and meat products have high total purine content, where as cereal foods contain low purine content. Generally, there is a positive association between protein and purine content in diet.

Table 1: High or low purine food sources.

Food Sources of PurineTotal purine content (mg of purine/100 g food)
Liver
286.4
Kidney
230.8
Poultry
130.7
lamb, roasted, chop
127.5
Pork, roasted, chop
119.0
Fish, white, fresh
115.9
Mushroom, fresh
46.9
Bread, crusted
15.7
Bread, white
12.2
Wheat flour
11.5
Cottage cheese
8.0
Plain yogurt
7.0
Rice, cooked
5.9

 

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