Every once in a while I happen to stumble upon something that makes my head spin. As if we all don’t have enough problems dealing with the more common causes of heart disease, I recently discovered that uric acid, the stuff that causes gout and that excruciating pain in your big toe (among other joints), is also a factor in promoting heart disease. Double ouch!
What is uric acid?
Every gout sufferer is probably all too familiar with uric acid. My interest was piqued by all those “Uloric®” commercials for the treatment of gout. You know, the curious one with the guy carrying around a giant flask of green fluid, which I guess is supposed to represent excess uric acid. I was curious so I thought I would Google it. Boy, was I surprised at what I found.
The best definition I have found came from an article right here at HeartConnect: “Uric acid is a chemical created when the body breaks down substances called purines. Most uric acid dissolves in blood and travels to the kidneys, where it passes out in urine. If your body produces too much uric acid or doesn't remove enough if it, you can get sick.”
The bottom line is if you eat an abundance of foods rich in purines or if you suffer from a temporary or permanent condition that reduces your kidneys ability to remove purine from your bloodstream, uric acid crystals will build up in your joints and cause considerable pain. Unfortunately, it seems that might not be the only damage that can occur.
The link between uric acid and heart disease
As I dug deeper I uncovered numerous epidemiologic studies that established uric acid as a strong predictor of high blood pressure and other heart related conditions. For example, the prestigious Cleveland Clinic analyzed 3,000 people at risk for cardiovascular events and found up to a 39 percent increased risk of death for each 1.0 mg/dL increase in uric acid blood level.
The National Heart, Lung, and Blood Institute's Family Heart Study studied nearly 5,000 participants and found that higher uric acid levels corresponded with a higher risk for developing plaque in the carotid arteries. Among men, uric acid levels greater than 5.0 mg/dl were associated with increased likelihood of plaque, and uric acid levels of 6.8 mg/dl or greater had a 75 percent greater likelihood. Women were at higher, although less exaggerated, risk as well.
The PIUMA Study which included 1,700 people showed a similar result with a four-fold increased risk for cardiovascular events in participants with a uric acid level of 5.2 mg/dl or greater in men and 3.9 mg/dl or greater in women.
A condition known as the “metabolic syndrome” (which includes numerous heart disease risk factors such as high triglycerides, pre-diabetes and excess weight) is strongly associated with uric acid. The massive NHANES III database maintained by the Center for Disease Control (CDC) clearly shows an increase in metabolic syndrome among participants as uric acid levels increase.
A deeper look at these and other studies suggests numerous ways uric acid could potentially increase the risk for heart disease.
Uric acid increases blood pressure. Uric acid is associated with endothelial dysfunction. The endothelium is a one-cell thick lining of your arteries that regulates expansion (blood pressure lowering) and constriction (blood pressure raising). Increased levels of uric acid are associated with increasing the tendency towards arterial constriction and higher blood pressure.
Uric acid triggers inflammatory responses. Many of us are aware that inflammation is a key contributor to heart disease. Uric acid has been implicated in numerous inflammatory markers such as C-Reactive Protein (CRP), monocyte chemo-attractant protein-1, nuclear factor kappa B, interleukin-1ß, interleukin-6, interleukin-6k and tumor necrosis factor-alpha.
Uric acid is associated with the abnormal growth of smooth muscle cells in arteries. Your arteries are not just motionless pipes. They are actually a type muscle known as “smooth muscle” which expand and contract as does your skeletal muscle (like your biceps). The growth of smooth muscle cells in the walls of arteries is associated with plaque growth. Those plaques can cause artery narrowing and plaque ruptures are the primary cause of heart attacks.
Uric acid has been found in arterial plaque. Researchers routinely perform studies of arterial plaque and have found uric acid in the plaque.
No one can yet say for certain whether high uric acid causes these conditions or whether these conditions cause high uric acid but the strong association is certainly cause for concern for any sufferer of heart disease. For those who share these concerns the next issue is how to limit our exposure to uric acid.
Foods, supplements, and drugs that increase uric acid
Uric acid and the pain of gout have been noted since the early annals of recorded history and have been associated with the intake of “rich” foods such as certain meats, cream, and alcohol. It turns out these anecdotal observations are largely true.
Meats and fish: Gout sufferers have been routinely advised to avoid meats and fish. While these food groups do increase uric acid levels not all these animal sources of uric acid are equal. The worst culprits include the fish sources anchovies, herring, salmon, sardines, trout, and meat sources bacon, liver, sweetbreads (beef brains), turkey, and veal.
Alcohol: Alcohol produces a “double whammy” by both increasing production of uric acid and blocking its elimination via the kidneys. The latest research indicates the biggest offender to be beer followed by hard liquors, while wine seems to be associated with a small decrease in uric acid levels (thankfully as wine seems to infer other modest heart health benefits as well).
Fruit and Fructose: Fructose from any source is strongly with increased levels of uric acid. Unfortunately, fructose has found its way into virtually every corner of our modern food supply with high-fructose corn syrup finding its way into soda, fruit drinks, beer, salad dressing, candy and breakfast cereals. Even so-called natural sources such as fruit and honey increase uric acid production. Here is a good HeartConnect article on fructose.
Sugar: In the previously mentioned NHANES III study, people drinking four or more sugar-laden soft drinks per day had higher uric acid levels - similar to those who ate significant amounts of meat. A follow-up study revealed that those who drank as few as two sugared soft-drinks per day experienced an 85 percent increase in gout.
Niacin: Unfortunately, niacin raises uric acid levels by as much as 11 percent. I say unfortunately because niacin is reported to have many heart healthy effects such as reduction in LDL (bad) cholesterol, triglycerides, and lipoprotein(a) (a new independent risk factor for early heart disease) and it also increases HDL (good) cholesterol. Ask your doctor whether the benefits of niacin outweigh the risks. Before going I might suggest this material on HeartConnect: Have you Tried Niacin
and Niacin: The Forgotten Heart Health Super Vitamin.
Diuretics: Diuretics are a first-line therapy for high blood pressure and many HeartConnect community members are using diuretics. The common thiazide class of diuretics such as hydrochlorothiazide and chlorthalidone can increase uric acid about 1.0 mg/dL. There is a robust series of discussions on blood pressure and diuretics at HeartConnect. Here are a few of the many: Alternative Therapies for High Blood Pressure, Discussions: Diuretics and Optimizing High Blood Pressure Treatment for Seniors: What You Need to Know.
How can I reduce uric acid?
Foods, nutritional supplements, and drugs that decrease uric acid include:
Cherries: I love cherries but cannot eat many as they raise my blood sugar. However, I was pleased to find anecdotal evidence that about eight ounces of Bing cherries per day may reduce uric acid levels.
Coffee: Heavy consumption (six cups per day) of both caffeinated and decaffeinated coffee has been found to reduce uric acid. However, the same was not true of tea.
Dairy products: Foods such as milk, cheese and yogurt have been shown to reduce uric acid. However, care should be taken as these foods have other potential risks and should be discussed with your doctor.
Vitamin C: Doses of about 500 milligrams per day seem to lower uric acid as much or more than heavy coffee drinking. Note, however, that increasing the dose does not seem to decrease uric acid any further.
Allopurinol: Allopurinol is a standard treatment prescribed for gout sufferers and can reduce uric acid by 30 percent to 50 percent, with few side-effects. Keep in mind this is a prescription drug!
Fenofibrate: I have used fenofibrate (Tricor®) in the past for various reason (but not to reduce uric acid) and was interested to find that this is yet another heart-related drug that seems to exert a reducing effect on uric acid. This leads me to wonder whether some heart drugs may have an additional “off-label” or pleiotropic benefit associated with uric acid reduction.
Losartan: This common blood pressure drug used by many HeartConnect members has been shown to also reduce uric acid.
Statins: Surprisingly, I found that two statins, atorvastatin (Lipitor®) and simvastatin (Zocor®) both reduce uric acid. However, rosuvastatin (Crestor®), which is what I use, does not.
Do I need to monitor my uric acid?
Whether heart-disease sufferers should start paying attention to uric acid even if they don’t experience painful “gout bouts” is a great question best answered by consulting with your doctor. I know I will now add it to the many risk factors I occasionally track over time.
For those interested, the typically mentioned acceptable uric acid levels are less than five mg/dL in males and less than four mg/dL in women.
Looking out for your heart heath,