Neither bad habits nor bad Hobbits were responsible for Peter Jackson’s gastric ulcer. The director of “The Lord of the Rings” is one of more than half a million people who are diagnosed annually with gastric (stomach) and duodenal (small intestine) ulcers. In 80 percent to 90 percent of the cases, bacteria called H. pylori are to blame. These bugs nestle into the lining of the stomach or intestines and damage the mucous coating, causing an open sore.

But a lot of people infected with these bacteria never develop an ulcer, so the exact cause remains a mystery. What do we know? These bugs can be transmitted by kissing or other close contact with an infected person. And you can weaken your stomach’s defenses against infection by smoking, consuming excess alcohol and regularly taking aspirin and other NSAIDs without adequate water.

Still, the bacteria aren’t all bad; they seem to protect kids from asthma. We also know that a balance of good and bad bacteria in the gut promotes robust health, so maybe it’s an overgrowth of H. pylori in your intestines that causes trouble.

If you get an ulcer, you may take bismuth and antibiotics such as clarithromycin, amoxicillin or tetracycline to knock out H. pylori. (Your spouse also should get treated so you don’t ping-pong the bacteria back and forth.) If you’d rather try some home remedies, Dr. Oz likes a drink that combines ground flaxseed and lemons (it’s the vitamin C) to fight the infection, and a combination of cranberries and oregano is reported to kill off H. pylori, too.

The You Docs — Mehmet Oz, host of “The Dr. Oz Show” and Mike Roizen of Cleveland Clinic — are authors of “YOU: Losing Weight.” To submit questions, go to www.RealAge.com. A King Features syndicate.