For years, physicians have recommended that patients at risk of heart attacks or strokes take a daily aspirin. In patients at risk, it can reduce one’s chance of having a heart attack by 50%. If taken while having a heart attack, aspirin can reduce your risk of dying. However, could taking an aspirin with a stomach-protecting enteric coating negate those benefits? Some researchers say yes.

After studying 400 healthy volunteers, researchers from the University of Pennsylvania are suggesting that the enteric coating may render the active aspirin inside ineffective for some people – leaving them at an increased risk of heart attacks or stroke.

Aspirin works by reducing acute or chronic inflammation, which causes some forms of pain and leads to heart disease, stroke, and many other chronic diseases later in life. By inhibiting different forms of the enzyme cyclooxygenase (COX-1 and 2), which is vital to the body’s inflammation pathway, inflammation is blocked and pain is prevented or stopped – at least until the body makes more enzymes.

However, some doctors believe a daily aspirin isn’t for everyone. The premise of this study stems from the debated concept that some people are “aspirin resistant” and don’t benefit from aspirin’s heart-protective properties. Past studies estimate between that 5% – 45% of the population does not experience the proper benefits of aspirin. Scientists aren’t sure why. Some consider this to be caused by internal biochemical differences that prevent aspirin from doing its job of preventing platelet aggregation, or metabolic differences that affect how aspirin is processed in the body. Some use these reasons to justify the need to not use asprin and instead prescribe more expensive platelet-blocking drugs like clopidogrel (Plavix).

The researchers recruited 400 healthy volunteers and screened their biochemical responses to a single 325mg dose of either regular “immediate release” aspirin or enteric-coated aspirin.

Within that group, they discovered 27 “aspirin-resistant” persons, who were then instructed to start taking a daily 81mg enteric-coated aspirin with another blood thinner for a week. After that week, their blood levels and “aspirin resistance” were assessed with blood and urine tests.

What is it about the enteric coating that makes some people “aspirin-resistant”? The researchers imply that the coating on the aspirin may be so thick, that it prevents the body’s digestive system from actually accessing the active drug, allowing it to pass in the digestive tract without accessing the bloodstream.

The coating exists in order to protect your stomach lining from acid. Taking aspirin increases one’s risk of stomach ulcers or gastrointestinal bleeding, and many studies show that taking a coated aspirin protects the stomach lining from potential damage. This study suggests that the coating could be doing its job too well.

No study is perfect, and every study, including this one, has its flaws. Some physicians, including Dr. Eric Topol, one of the authors of the 2003 study on “aspirin-resistance,” thinks this study should have been done on volunteers “who actually have heart disease or other chronic illnesses who are taking various medications.” Others may take issue with the small number of participants or the disproportionate number of volunteers who received a regular, non-coated aspirin. Only 40 volunteers out of 400 actually took the non-coated aspirin, which would make it much easier to find “aspirin-resistant” participants among the 360 volunteers who took the coated aspirin. However, both the researchers and medical staff at The Dr. Oz Show agree that more research is needed to reach a more informed conclusion.

So what does this mean for you? If you are more concerned about the aspirin’s enteric coating than its protective effects on your stomach, you may want to consider switching to a regular non-coated aspirin. It’s comparable in price. However, if you have a history of gastrointestinal bleeding or gastric ulcers, talk with your doctor about taking an enteric-coated aspirin versus taking a more stomach-safe medication, like clopidogrel (Plavix).

Remember, if you or a loved one are experiencing the symptoms of a heart attack, taking a coated aspirin tablet is better than taking no aspirin at all