Dear Doctor: I had problems with acid reflux for years -- until I started taking a proton pump inhibitor. Now I read they may raise the risk of stomach cancer. I don't want to go back to the days before my PPI, but I don't want cancer either. What should I do?

Dear Reader: I understand the life-changing potential of proton pump inhibitors (PPIs). These drugs are potent inhibitors of the acidity of the stomach. They help heal stomach ulcers, treat acid reflux and, in combination with antibiotics, combat Helicobacter pylori (H. pylori) infections. These infections increase the risk of stomach cancer, and eradicating the bacteria reduces the rate of cancer among those infected by 33 to 47 percent. Many people take the drugs long-term to decrease acid reflux and relieve stomach discomfort, so it's reasonable to question the safety of this, especially in light of the recent study.

But let's take a closer look at that study. It assessed the impact on 63,397 individuals successfully treated with drugs for H. pylori in Hong Kong, comparing those who then took a proton pump inhibitor to people who then didn't take any medication and to people who then took drugs known as histamine 2-blockers or H2 blockers, such as Zantac, Pepcid or Tagamet.

Participants were then followed for an average of 7.6 years, with 153 of them developing stomach cancer. Although this type of cancer is rare in the population, people who used PPIs at least once a week had a more than twofold risk of developing stomach cancer compared to the group using H2 blockers. Those who used PPIs daily had an eightfold risk of developing stomach cancer compared to the other group.

Length of use was linked to greater cancer risk as well. Thus, the study appeared to show a dose-dependent increase in the risk of gastric cancer. This correlation was specific to PPIs because H2 blockers did not show this increase.

But there are problems with this study. First, the average age of the PPI users was more than 10 years greater than that of the non-PPI users. Greater age itself is a risk factor for cancer. Second, participants in the group using PPIs were more likely to be obese, have diabetes, and be smokers or users of alcohol -- all of which are risk factors for gastric cancer. Of note, this study was in a mostly Asian population, which generally has a greater rate of gastric cancer.

Still, a 2017 Swedish study reached a similar conclusion. It looked at 797,067 people who consistently used PPIs, and researchers found that the rate of stomach cancer was three times greater in this population than in the general population. Again, this increased risk was not seen among people who used H2 blockers. But this study, too, was less than clear. Here, the rate of stomach cancer incrementally decreased such that people who took PPIs more than five years had a lower rate of stomach cancer than the general population.

In short, the data on PPI use and stomach cancer risk is not absolutely convincing. But I would still be wary of using proton pump inhibitors long-term, especially if you've been diagnosed with H. pylori infection. I'd recommend that you talk to your doctor about using an H2 blocker instead.

(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. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm so confused by the new blood pressure guidelines. Yesterday, my blood pressure was normal. With the new guidelines, though, I'm now considered to have high blood pressure. Is my doctor going to put me on medication?

Dear Reader: Ever since the new blood pressure guidelines were released by the American College of Cardiology and the American Heart Association in November, we've been getting quite an earful. We're hearing not only from our patients, but from family and friends as well. People are surprised, upset, worried and, as you state in your letter, just plain confused.

The truth is that blood pressure goals have long been (and quite likely will always remain) controversial among the medical community. Back in 2014, when a panel of medical experts loosened blood pressure guidelines for some older Americans, there was an immediate backlash. Now, with guidelines being tightened, the debate has erupted again. Rather than focus on the history of blood pressure guidelines and the various schools of thought behind each iteration, we think it's more useful to talk about where things stand now, how the current guidelines affect us and what changes each of us can make to get better numbers.

Heart disease, which accounts for one quarter of all deaths in the United States, is the leading cause of death among both women and men. High blood pressure, or hypertension, is second only to smoking as a preventable cause of heart attack and stroke. At this time, guidelines state that normal blood pressure falls into a range below 120/80. The top number, known as systolic pressure, refers to the pressure in your arteries as your heart contracts. The bottom number is diastolic pressure, which is the pressure in your arteries between heartbeats. When taken together, the numbers offer a snapshot of your cardiac health.

People with a top number that falls between 120 and 129, and whose bottom number falls below 80, are considered to have "elevated" blood pressure. A top number of 130 to 139, and a bottom number of between 80 and 89, is considered to be stage 1 high blood pressure. Readings greater than 140/90 are stage 2 high blood pressure. Both stage 1 and 2 require medication.

Part of the uproar over these new guidelines is they are likely to push close to half of all Americans out of the normal range. However, this doesn't automatically mean blood pressure medication for everyone. In fact, the aim of the guidelines update is to give people ample warning of pending blood pressure problems. Because it has no obvious symptoms, high blood pressure is known as the silent killer. By catching changes early, people with elevated blood pressure can take steps to achieve healthier numbers through lifestyle changes and interventions.

-- Lose weight.

-- Stop smoking.

-- Exercise regularly.

-- Watch your diet.

-- Cut back on salt.

-- Limit alcohol.

-- Cut back on caffeine.

-- Reduce stress.

-- Keep regular track of your blood pressure.

We're sure you've heard this all before. But knowing what to do isn't the same as actually doing it. We believe this is an important discussion, so we'll be back next week with details about how and why each of these steps is important to your good health.

(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. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I thought mushrooms were kind of a nonstarter from a nutritional standpoint, but now I read they are the best source of the antioxidants linked to anti-aging. Have I underestimated their health benefits? They're kind of icky, but I'll eat them if I have to.

Dear Reader: "Icky and slimy" was the way I described mushrooms as a kid. I would push them to the edge of my plate, hoping my mom wouldn't notice my disgust for the fungi. Eventually, however, I started to like them and now enjoy many species of edible mushrooms. They're low in calories, have a small degree of protein, are a good source of fiber and contain multiple B vitamins and selenium. But decrease aging?

It's true that mushrooms contain many antioxidants, including glutathione and ergothioneine. That seems to be where these claims start. Glutathione helps protect and repair cells damaged by everyday life, pollution and harmful influences. Although deficiency can lead to multiple health problems, it isn't known whether supplementation can help people without a deficiency. Ergothioneine is found throughout the human body and in black beans, kidney beans -- even mushrooms. Although ergothioneine has shown antioxidant properties in the laboratory, little is known of its physiological role in humans.

One recent study, likely the one you read about, measured the amounts of these antioxidants in different mushrooms. The authors found that higher levels of ergothioneine correlated with higher levels of glutathione. Maitake mushrooms had high levels of glutathione, for example, while chanterelles had the lowest amounts of both glutathione and ergothioneine. Porcini and yellow oyster mushrooms had the highest amounts of ergothioneine. Regular white, crimini and portabella mushrooms had relatively low levels of both antioxidants. Some news coverage of this study extrapolated by linking levels of antioxidants to an impact on aging.

That may be a stretch, but mushrooms do have immune-stimulating and anti-inflammatory properties. For example, mushrooms contain arginine, which has been shown to inhibit the growth of tumor cells and decrease the rate of cancer metastasis. Some edible mushrooms also contain fatty acids and lectins that decrease inflammation and may inhibit growth of tumors such as breast cancer. Further, phytochemicals in mushrooms such as indoles, phenols and terpenoids have been shown to decrease inflammation. All these compounds are potentially important because chronic inflammation can lead to cancer and vascular disease, even as inflammation and oxidation can lead to harmful effects on nerve cells in the brain.

The effects on the brain bring us to one of the biggest worries in aging: the risk of dementia. Countries such as Italy and France, which have high dietary amounts of ergothioniene, have substantially lower rates of Alzheimer's and Parkinson's disease compared to countries such as the United States with low amounts of dietary ergothionene.

Now, all this information about mushrooms and their link to health and aging is far from conclusive. In fact, it may be wishful thinking.

Yes, mushrooms contain many compounds, including antioxidants, which are good for your health, but so do many foods, such as berries, oranges, plums, grapes, kale, spinach, Brussels sprouts and broccoli. Perhaps you should simply add mushrooms to this list.

In other words, give them a try. You may find some varieties more appealing than the typical white mushrooms, and you may be surprised, as I was, that you like the taste.

(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. Owing to the volume of mail, personal replies cannot be provided.)