By Christine Haran
To some, gout sounds like a disease out of a novel about the 16th century. That's probably because this joint disease famously afflicted Henry VIII, Leonardo de Vinci, Voltaire and other luminaries from the past.
It's been theorized these historical figures had gout because they had the money to enjoy red meat and seafood, foods rich in a group of compounds called purines, which have been thought to be associated with an increased risk of gout. Purine leads to high levels of uric acid, which can build up in the joints and crystallize, causing attacks of gout. Today, more people of all income brackets have access to red meat and seafood and tend to eat fewer protective fruits, vegetables and low-fat diary products. As a result, gout is more of an equal-opportunity disease, affecting more than 5 million American adults.
Some speculate that the followers of the popular high-protein, low-carb diets may be at particular risk. And a new study confirms what has long been suspected: that there is a link between red meat and seafood and increased gout risk. It also found that some foods protect against gout. The 12-year study, published in the March 11 issue of The New England Journal of Medicine, found that each piece of meat someone ate in a day increased gout risk by 21 percent and each piece of seafood increased risk by 7 percent, but that one low-fat diary product a day reduced risk by about 21 percent. Below, Hyon K. Choi, MD, an attending rheumatologist at Massachusetts General Hospital in Boston, discusses how to lower gout risk through diet.
What is gout?
Gout is caused by deposits of uric acid in connective tissue, often in joints of the feet and ankles, which lead to inflammatory arthritis; uric acid is produced when purine is metabolized. Symptoms include swelling, redness, stiffness and severe pain. Although attacks of gout can subside in a few days, repeated attacks can cause permanent joint damage and the disease frequently results in substantial disability, occupational limitations and substantial utilization of medical services.
Treatment includes pain-relieving drugs such as non-steroidal anti-inflammatory drugs and for more serious outbreaks, corticosteroid drugs. Most people with gout eventually require long-term prophylactic medications.
Why do people experience attacks of gout?
It is not entirely clear, but the idea is there are certain triggering factors that make the uric acid more crystallized in tissues. Those triggering factors have been thought to be binge drinking or binge eating of high-purine foods, and perhaps joint trauma, but these factors have not been well proven in clinical studies.
How is gout diagnosed?
Gout is diagnosed based on the characteristic features of gout attacks, such as swelling, redness and stiffness in the characteristic joints. However, the definitive diagnosis is based on the visualization of uric acid crystals under microscope from joint fluid, which is obtained with by putting a needle into an affected joint. Most of the time, this test is performed by a rheumatologist.
Who is at increased risk for gout?
The risk factors include older age, male sex, overweight or obesity, family history of gout, heavy alcohol use, lead poisoning or toxicity, and high animal purine intake. Purine is the source of uric acid, so if you eat a lot of purine-rich foods, the idea is that your uric acid level will rise and increase the risk of gout, eventually.
Can people have high uric acid levels and not develop gout?
Yes, a sizable proportion of those with a high level of uric acid do not develop gout. More studies are necessary to identify which factors may be protective in those people.
What does your study tells us about the risk associated with purine-rich foods?
A number of dietary factors have been suspected of causing gout since ancient times, but never proven. For example, patients with gout have been typically advised to avoid habitual intake of purine-rich foods such as meat, seafood, purine-rich vegetables and animal protein. This study comprehensively investigated these suspected dietary factors and others and confirmed some of the suspicions, exonerated the others, and also discovered new protective factors. These results provide scientific evidence directly relevant to the population at risk for developing gout.
This study showed the consumption of meat, particularly red meats, significantly increases the risk of gout, and that the consumption of all types of seafood tended to carry even a higher risk. Notably no increased risk was seen with consumption of purine-rich vegetables such as peas, beans, mushrooms, cauliflower, spinach and oatmeal.
Why do you think that the purine-rich vegetables did not raise risk?
It is possible that the purine levels may be lower in vegetables and that the kinds of purine may be different. Also, different sources of purines are absorbed in the intestines in different ways. So the degree of bioavailability as a source of uric acid varies depending on the source of purines, and animal purine-rich foods may be absorbed better than vegetable ones, which might lead to the production of more uric acid.
What role did protein appear to play in risk?
In the past, protein was thought to one of the causes of gout. But there have been studies that suggest that protein increased the excretion of uric acid, so the protein caused uric acid to get out of the body quicker. That suggests a protective effect.
What this study has shown is that if you look at the overall protein intake, there is no association with gout. But if you look at low-purine, high-protein food—that includes dairy products, which are low in purine but relatively high in protein—they had a huge protective effect against the risk of gout. Vegetable proteins showed a protective effect as well.
Do you think people on some of high-protein diets might be at increased risk for gout?
Reducing red meat consumption may be generally recommended, but we didn't find an association with poultry meat. So other animal meat may be OK, as far as the risk of gout is concerned. This study did not investigate heart disease or cancer or other diseases associated with these dietary factors.
If someone was trying to lower their intake of purine, what would you recommend?
The precise amount of purine in each food is not really available, and there are other factors besides the absolute amount of purine that may be operating in its association with gout.
Based on what we know, reducing red meat consumption may be generally recommended because it also has been associated with other major health problems, such as colon cancer and diabetes. But the recommendations for seafood or dairy intake should be individualized and discussed with a physician or dietician, taking into account the potential impact on the individual's other health issues. Healthy foods such as vegetables, including vegetable protein and high-purine vegetables, do not need to be restricted.
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