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Introduction

Two or three decades ago, purines were recognized for primary two reasons: (1) as building blocks for DNA (the primary genetic material in our cells) and (2) as substances that could be broken down to form uric acid and potentially increase our risk of gout. Gout is a form of arthritis (sometimes called gouty arthritis) that can be extremely painful and results from excessive build-up of uric acid in our body, leading to formation of uric acid crystals that get can deposited in our joints. Beyond these two key areas of interest, purines did not enjoy a lot of mainstream attention in scientific research.

Today researchers understand that purines are far more important contributors to our health than we might be otherwise be led to believe from a focus on DNA and gout. Thanks to extensive research on the role of purines in the health of our cardiovascular system and digestive system (including our mouth, stomach, and intestines), we now know that purines have their own special receptor system on our cells that allow them to connect up with the cell membranes and have far-reaching effects. In our cardiovascular system, these effects include many aspects of heart function including blood flow and oxygen delivery. In the digestive system, there are impacts on fluid secretion and the movement of food as it undergoes the process of digestion. The initial discovery of two basic purine receptor families (P1 and P2) has now been followed by identification of at least four P1 subtypes; and a division of P2 into P2X and P2Y with seven subtypes of P2X ion channel receptors and eight subtypes of P2Y G-protein-coupled receptors. Going from 2 basic families to 19 different receptor types has allowed researchers to get much more specific about the potential of purines to influence our health, and dozens of studies are underway to determine exactly how "purinergic signalling" serves to impact our blood flow, heart function, inflammatory responses, experience of pain, digestive function, and absorption of nutrients. So as you can see, research on purines has come a very long way!

Purines in Food

Given what scientists now recognize as the widespread importance of purines in our health, it should not be surprising to learn that purines are naturally present in all foods. You're going to find at least 10-15 milligrams of purines in 1/2 cup of virtually all foods, including the 100 foods we profile on our website. This amount of purines would be considered a small amount—even if a person had been asked to follow a purine-restricted diet by their healthcare provider. (We'll tell you more about purine-restricted diets in the next section.)

The range of purines found in food can also vary widely. While most foods contain 10-15 milligrams of purines in a ½-cup serving, some foods can contain 500-1,000 milligrams or more in this same serving size. For the most part, these much higher purine foods involve the organ meats of animals—including liver, spleen, and heart. None of our 100 WHFoods rise to this very high level of purine content. In general, animal foods and seafood—including our WHFoods meat, poultry, and seafood—contain moderate levels of purines in the 100-400 milligram range (per half cup).

It's worth noting here that plant foods also typically fail to rise above this 100-400 milligram range, and often come up between 15-100 milligrams per ½-cup serving.

Meat extracts, yeast extracts, and yeast itself belong in a special group when measuring food purines. Each of these food-related substances would be classified as high in purines.

Gout, Purines, and Diet

As described earlier, gout is a form of arthritis in which excessive build-up of uric acid in our body can lead to the formation of uric acid crystals that can get deposited in our joints and become the source of severe pain. Excessive build-up of uric acid in our blood can also lead to formation of uric acid kidney stones. However, in the U.S., formation of uric acid kidney stones is far overshadowed by the formation of calcium-based stones. Calcium oxalate and calcium phosphate (also called hydroxyapatite) stones account for about 95% of all stones in first-time occurrence of kidney stones. In addition, about two-thirds of all stones are less than 5 millimeters in diameter and undergo spontaneous passage through the urine.

In previous decades, restriction of dietary purines to a level of 100-200 milligrams per day was not an unusual recommendation among healthcare organizations focused on gouty arthritis and its treatment. At present, a good number of organizations have adjusted their gout-treatment and prevention guidelines to include routine intake of purine-containing vegetables, including allowance for moderate amounts of vegetables that have moderately high purine content (above 100 milligrams per ½-cup serving). These adjustments have been based on relatively new research showing different levels of gout risk from purine-containing vegetables versus purine-containing animal meats and seafood. In fact, some gout prevention protocols no longer call for any restriction on vegetable intake. You'll note that we have separated out animal meats and seafood from dairy foods in this plant-food-versus-animal food example since some studies show that low-fat dairy foods may be associated with decreased risk of gout.

One interesting aspect of the vegetable and gout research has been the repeated finding that higher intake of vitamin C can lower risk of gout. At WHFoods, three of our Top five foods for vitamin C are vegetables&mdashlnamely, bell peppers, broccoli, and Brussels sprouts.

One further interesting finding in recent research on diet and risk of gout has been the finding that greater intake of plant (versus animal meat) proteins may be associated with a decreased risk of gout. While further research is needed in this area, we view this finding about plant proteins as being consistent with an overall relaxing of previous dietary restrictions on vegetable purines as a means of lowering gout risk.

WHFoods Recommendations for Purines

We don't know of any science-based reason for you to avoid or limit any of our 100 WHFoods based on their purine content. In fact, because of their key role in healthy functioning of our cardiovascular system and digestive tract, the purine content of our 100 WHFoods may very likely to provide you with health benefits. It's possible that your healthcare provider might ask you to restrict your overall animal meat and seafood intake if you are being asked to follow a purine-restricted diet. But in the absence of a medical reason for restriction of purines in your meal plan, we do not view these food components as a problem in any way. And based on the most recent research findings, they may even be providing you with health benefits that you would not otherwise be getting from your food.

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