Dear Doctor: Because I had an ulcer, three years ago a doctor wrote me a prescription for Prilosec and told me I had to take it for the rest of my life. But lately, articles in the newspaper have seemed to contradict his thinking, suggesting that Prilosec and similar medicines can cause heart problems. What's your opinion?

Dear Reader: Prilosec is one of many proton pump inhibitors (PPIs) that include Prevacid, Aciphex, Protonix, Nexium and Dexilant. These drugs work by blocking the formation of hydrogen chloride in the stomach. This very strong acid is necessary to break down proteins so that they can be absorbed by the small intestine.

I don't know the specifics about the causes of your stomach ulcer -- the size, the depth, whether it was a bleeding ulcer or caused by aspirin or other anti-inflammatory medications -- but I do agree with your doctor that a proton pump inhibitor would be necessary for the healing of the ulcer. These drugs decrease the acidity of your upper gastrointestinal tract, allowing for an ulcer to heal. The normal duration for treatment is from two to 12 weeks.

In some circumstances, a PPI needs to be continued indefinitely, such as when an ulcer doesn't heal, when an older patient has an ulcer that's larger than 2 centimeters, or when a patient has three or more ulcers per year. People with recurrent acid reflux also need to be on prolonged courses of proton pump inhibitors.

While there are benefits to these medications, there also are downsides. Any drug that changes the normal physiological process of the body can have unintended consequences, and PPIs are no exception. With prolonged use, the decreased formation of hydrogen chloride in the stomach can decrease calcium absorption and bone strengthening, increasing the risk of osteoporosis. Prolonged use can also reduce the absorption of magnesium and B12, and increase the risk of intestinal infections, such as those caused by Clostridium difficile, leading to severe diarrhea.

As for your specific question about proton pump inhibitors and heart disease, a 2014 study published in the International Journal of Cardiology compared more than 126,000 people who took PPIs with an equal number who didn't. After 120 days, researchers found a 58 percent increase in the risk of heart attacks among those who took them. The biggest problem with this study is that the authors couldn't assess whether those in the study smoked cigarettes, were obese or had a family history of heart disease.

A 2015 study published in the journal PLOS One analyzed large amounts of data both from people who used PPIs for gastroesophageal reflux and those who didn't. In this study, researchers found a 16 percent increase in the rate of heart attacks among those who took PPIs. The authors didn't find this risk in those taking acid-reducing histamine-2 blockers, such as Zantac, Pepcid or Tagamet. The authors, however, did note that people who take proton pump inhibitors may be sicker patients to begin with and thus may have an increased risk of having a heart attack.

Then there was a 2016 study in The American Journal of Medicine that focused on people taking Prilosec with two blood thinners after having either angina or a heart attack. After 110 days, researchers found no increase in the risk of heart attacks.

Finally, an analysis of 11 studies -- with a total of more than 84,000 patients -- looked at use of proton pump inhibitors in people taking the blood thinner Plavix after having an angioplasty. The authors found a 37 percent increase in the rate of heart events among those taking the proton pump inhibitor Clopidogrel with Plavix and those taking just Plavix, but they found no difference in death rates. The findings suggest that PPIs decrease the ability of a blood thinner, like Plavix, to work.

Overall, it's clear we need better studies of the potential link between proton pump inhibitors and heart disease.

Your worry about taking Prilosec for the rest of your life is understandable, but you're probably on the drug for a good reason. Just know that there can be long-term side effects, and be aware of them. You can also ask your doctor to keep you apprised of any new research on long-term use of PPIs.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095.)

Dear Doctor: Our neighbor's kids, who don't have access to computers, video games or other technology, spend a lot of time playing together outdoors. How can we wean our own kids from their screens without causing a family rebellion?

Dear Reader: You're facing a real challenge that has crept up on parents in the last decade or so. Once the argument was simply about getting kids to turn off the TV. Today, though, an array of devices effortlessly capture our children's -- and let's be honest, our own -- time and attention.

When the Kaiser Family Foundation conducted a study about screen time six years ago, the results were eye-opening. Its research showed that children between the ages of 8 and 18 spend more than 7 1/2 hours each day in front of screens of one kind or another. And that didn't include the use of a computer for homework.

Why is this a problem? Children who spend that much time immobilized in front of a screen, whether it's the TV, a computer, smartphone or video game console, are at significantly greater risk of obesity. There is evidence that kids who play a lot of video games are more likely to display aggressive behavior. Sleep problems due to sustained screen use are common. And a preference for the immersive world of a tech device over the companionship of siblings or friends can lead to antisocial behavior.

So how do you win the battle for your kids' attention?

The biggest challenge may be that, first, you need to set a good example. How many times have you driven by a playground and seen parents completely absorbed in their smartphones? If the tug of the screen is difficult for an adult to resist, imagine its effect on young and malleable minds.

Begin by setting strict guidelines for yourself and (here's the hard part) following them. Once you've got your own screen time under control, you're on solid footing to address your children's habits.

The American Academy of Pediatrics recommends no media use for children younger than 18 to 24 months old. One hour per day of high-quality programming is deemed to be OK for children 2 to 5 years old. Although the academy no longer makes a specific recommendation regarding children 6 and older, two hours per day of screen time is a reasonable goal.

-- For best results, start with a family discussion. Tell your children what you're doing and why. Explain that they will sleep better, have more energy and will have time for other activities.

-- Create screen time limits and take a few weeks to ease into them. Tapering off will allow your family to work together toward a common goal.

-- Make a weekly chart to log screen time and go over the results as a family.

-- Create screen-free bedrooms for everyone in the family. (Yes, adults too.)

-- Meals should be screen-free, including smartphones and TVs.

-- Plan alternate activities, like taking a family hike or bike ride, baking cookies together or having a game night.

-- Resist the urge to use screen time as either a reward or punishment.

Although it may be rough going at first, by helping your kids to look away from their screens, you're giving them a real and loving gift.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095.)

Dear Doctor: Is walking or running on a treadmill as good as walking or running on concrete streets or sidewalks?

Dear Reader: This is an interesting question, because the definition of "as good as" is quite ambiguous. Good can be defined as having cardiovascular, or other, health benefits, but it can also be defined as having mental or social health benefits, such as those that come from running or walking with another person. For the purposes of this question, let's look at the cardiovascular aspects.

A 1985 study in the journal Medicine & Science in Sports & Exercise measured the amount of oxygen consumed during both treadmill running and outdoor running. The level of oxygen consumption, termed VO2, is a measure of energy expenditure with exercise. The subjects ran 950 meters on a treadmill and outdoors. The subjects also ran at varying speeds and at different elevation grades. The investigators found no difference in the amounts of oxygen consumed with either the outdoor or treadmill running. This was consistently seen, even when there were changes in speed or elevation grade.

A 1996 study in the Journal of Sports Sciences similarly looked at the differences in VO2 in nine athletes who ran both outside and on treadmills at varying speeds and elevation grades. This study showed some significant differences in the VO2 between outside and treadmill running. Overall, those who exercised outside consumed more oxygen than those on a treadmill. This may be partially related to the wind resistance seen with outdoor exercise.

The authors concluded that running outside on flat terrain was similar to treadmill running at a 1 percent elevation grade. So, if you want to equate your treadmill running to what you might experience outside, place your treadmill at a 1 percent grade.

But treadmill running is quite dissimilar from outdoor running in one respect: Your muscles respond differently. Because a treadmill is powered by a machine, not your body, the hamstring muscles are not used as much -- something you may notice if you normally run on a treadmill and then decide to go running outside. In that case, to prevent an injury, slow your pace.

A significant benefit from running on a treadmill is that the belt of the treadmill is much more forgiving than the concrete of the sidewalk. While there has been no long-term study regarding the benefit of treadmill running on the joints, it stands to reason that exercising on a treadmill could decrease the incidence of knee and back injuries.

Alternatively, one definite positive from outdoor running is that it's less monotonous than treadmill running. The changes of scenery and terrain keep things interesting. When I run on a trail, I am constantly looking at the rocks I have to avoid, and I often have to move laterally to follow the trail. When I get to the top of the mountain, looking down at the expanse of earth below me, I get a perspective that is much different than running on a treadmill. This cannot be measured, but it motivates me to run again.

If you like running or walking on a treadmill, by all means continue doing this. The cardiovascular benefits are similar to outdoor exercise, and it may be less hard on your joints. The most important thing is to take the time and exercise, whether it be inside or outside.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095.)