What Are Purines?
Purines are organic molecules that include nucleotides (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, breakdown of purine molecules, 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, hyperuricemia, however, it can cause gout, and other health problems.
Gout is a form of arthritis caused by accumulation of uric acid crystals in joints, such as in the big toe.
A 12-year study that followed eating habits and gout incidence in a large number of men found that eating purine rich food, 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 increased risk of gout. A recent study also found a positive association between fructose (a type of sugar found in fruits) 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 or uric acid. The Japanese Society of Gout and Nucleic Acid Metabolism, to prevent an abnormal high level of uric acid in blood (hyperuricemia) and gout, recommends to keep purine consumption to under 400mg per day.
According to the Japanese Society of Gout, a blood urate level below 7mg/dL is considered to be normal and above it, hyperuricemia and gout risk.
Food Purine Content Groups and Gout Risk
According to a Japanese study, foods can be classified into five groups based on the total purine content and level of risk to hyperuricemia and gout.
| Total purine content (mg per 100 gram food) | Category |
|---|---|
| > 300 | Very High |
| 200 - 300 | High |
| 100 - 200 | Moderate |
| 50 -100 | Low |
| < 50 | Very Low |
Foods High or Low in Purines
In the following tables are estimates of total purine content in a variety of food items, presented in descending order. Total purine content is based on the sum of all the four purine bases. 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 Purine |
Total purine content (mg/100g) |
|---|---|
| Liver | 286.4 |
| Kidney | 230.8 |
| Poultry | 130.7 |
| lamb, roasted, chop | 127.5 |
| Pork, roasted, chop | 119.0 |
| Fish, white, fresh | 115.9 |
| Raisins | 107.0 |
| Brocoli | 81 |
| Apricot, dried | 73.0 |
| Brussels sprouts | 69 |
| Sweetcorn | 52.0 |
| Cauliflower | 51.0 |
| 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 |
| Peach | 21 |
| Orange | 19.0 |
| Apple | 14.0 |
Purine content also varies depending on the type of meat cuts or organ.
Table 2: Purine content in chicken, pork, lamb, and beef parts.
| Purine sources | Total purine content
(mg/100g) |
|---|---|
| Chicken organs and parts | |
| chicken, liver | 243 |
| chicken, liver | 236.1 |
| Chicken, heart | 223 |
| Chicken, drumstick | 132.3 |
| Chicken, breast | 130.7 |
| Chicken, gizzard | 130.5 |
| Chicken, thigh | 126.5 |
| Chicken, skin | 104.6 |
| Pork, beef, and lamb organs |
|
| Pork, liver | 289 |
| Beef, kidney | 213 |
| Beef, liver | 197 |
| Beef, heart | 171 |
| Lamb, heart | 171 |
| Beef, brain | 162 |
| Lamb, liver | 147 |
According to a study that compared free and total purine bases content in meat products (steak, beef liver and haddock fillets) before and after cooking, cooking appears to increase the level of free and total purine bases in a diet.
Table 3: Total purine content in raw and cooked foods.
| Meat products | Total purine content
(mg/100g) |
|---|---|
| Liver, raw | 202.2 |
| liver, boiled | 237.0 |
| liver, broiled | 236.1 |
| Steak, raw | 105.9 |
| Steak, boiled | 107.8 |
| Steak, broiled | 121.0 |
| Haddock, raw | 101.7 |
| Haddock, boiled | 94.7 |
| Haddock, broiled | 118.7 |
Table 4: Purine content in seafoods (fish and crustaceans, fresh and canned), and vegetables (legumes).
| Purine food sources |
Total purine content (mg/100g) |
|---|---|
| Fresh seafoods | |
| Anchovies | 411 |
| Sardines | 345 |
| Salmon | 250 |
| Mackerel | 194 |
| Clams | 136 |
| Squid | 135 |
| Canned seafoods | |
| Sardines | 399 |
| Herring | 378 |
| Anchovies | 321 |
| Mackerel | 246 |
| Shrimp | 234 |
| Tuna | 142 |
| Oysters | 107 |
| Salmon | 88 |
| Clams | 62 |
| Dried legumes | |
| Blackeye peas | 230 |
| Lentils | 222 |
| Great northern bean | 213 |
| Small white bean | 202 |
| Split peas | 195 |
| Pinto bean | 171 |
| Red bean | 162 |
| Large lima bean | 149 |
| Baby lima bean | 144 |
| Cranberry bean | 75 |
| Garbanzo bean | 56 |
More on gout and diet:
Purine content in alcoholic drinks, seasonings and supplements
Purines and uric acid content in beef, pork and chicken
Purines and uric acid content in vegetables, fruits, eggs, dairy products
Purines and uric acid content in fish and seafood
Gout causes, diagnosis, symptoms, and cure
Food high or low in uric acid
Gout and diet: Serum uric acid level and coffee and tea intake
Uric acid reducing foods
Gout Causes: Food High in Purines and Uric Acid, and Alcohol
Low purine diet cookbooks and gout related books
References:
Álvarez-Lario B, Alonso-Valdivielso, JL. 2014. Hyperuricemia and gout; the role of diet. Nutr Hosp. 29(4):760-70.
Clifford, Andrew J. and Story, David L. 1976. Levels of Purines in Foods and Their Metabolic Effects in Rats. J. Nutr. 106: 435-442.
Brule, D. Sarwar, G., and Savoie, L. 1988. Purine content of Selected Canadian Food Products. Journal of Food Composition and Analysis 1(2): 130-138.
Brule, D., Sarwar, G. and Savoie, L. 1989. Effects of methods of cooking on free and total purine bases in meat and fish. Can. Insti. Food Sci. Technol. J. Vol. 22(3): 248 - 251.
Choi, H. K., Atkinson, K., Karlson, E. W., Willett, W., and Curhan, G.. 2004. Purine-Rich Foods, Dairy and Protein Intake, and the Risk of Gout in Men. The New England Journal of Medicine, Vol. 350(11):1093-1103.
Clifford, A. J. and Stroy, D. L. 1976. Levels of purines in foods and their metabolic effects in rats. Journal of Nutrition 106: 435-442.
Kaneko K, Aoyagi Y, Fukuuchi T, Inazawa K, and Yamaoka N. Total Purine and Purine Base Content of Common Foodstuffs for Facilitating Nutritional Therapy for Gout and Hyperuricemia. Biol. Pharm. Bull 37(5), 709 - 721 (2014).
Gibson, T., Rodgers, A. V., Simmonds, H. A. and Toseland, P. 1984. Beer drinking and its effect on uric acid. British Journal of Rheumatology, 23: 203 - 209.
Young, L. L. 1980. Evaluation of four purine compounds in poultry products. Journal of Food Science 45: 1064-67.