Aspirin can nix headaches and help your heart, but it also might boost your health in another way: Taking the drug may ward off cancer, research from Harvard Medical School found.

After studying more than 135,000 adults all over the age of 30 for up to 32 years, the researchers found that those who popped aspirin regularly were 3 percent less likely to develop any kind of cancer.

But the results were far more substantial when looking at your gut: Those who took aspirin were 15 percent less likely to develop gastrointestinal cancer and 19 percent less likely to get colorectal cancer

How Aspirin Reduces Cancer Risk

One possible reason: Aspirin blocks an enzyme called cyclo-oxygenase-2, which halts the production of inflammatory substances called prostaglandins, says study author Andrew Chan, M.D., M.P.H.

And blocking prostaglandins is important for your cancer risk, since they can promote the uncontrolled growth of cells in your gastrointestinal tract. That makes a cancer-causing mutation more likely to pop up.

Your GI tract may be more vulnerable to these effects than other places in your body, which may explain why aspirin wasn’t as effective as preventing other types of the big C, says Dr. Chan.

What’s more, the researchers found that taking as little as half an aspirin tablet once a week was enough to show some cancer-preventing benefits.

That’s good for your gut, since higher doses of the drug are more likely to cause bleeding in your GI tract, says Dr. Chan. Prostaglandins also protect your gut’s lining, so blocking them too intensely may make bleeding more likely to occur.

But more research is needed to determine what dose may be best for cancer prevention, he says.

Still, guys who are over 50 or who have a family history of GI cancer can talk to their doctor about whether starting an aspirin regimen can be helpful. If you have a strong family history of the cancer, ask you doctor if you should start it younger.

Just don’t think of aspirin as a cure-all, Dr. Chan says. You still need to follow proper screening guidelines—like a colonoscopy at age 50 for guys without a family history—to get the greatest prevention benefit.