Once rare, esophageal adenocarcinoma (a cancer of the esophagus) is now the fastest-increasing cancer in several developed countries, including the U.S. and the U.K., Blaser notes. In both places, it now constitutes roughly half of all esophageal cancer cases. Yet people who carry a certain strain of H. pylori are almost half as likely to get this disease, according to a recent review of medical literature (published in the October issue of Cancer Prevention Research).
Co-author Dr. Farin Kamangar, a research fellow at the U.S. National Cancer Institute, says H. pylori likely reduces the risk of esophageal adenocarcinoma in two ways. The bacteria “makes your stomach produce less acid,” he explains. (Acid reflux is a risk factor for the disease.) It may also impact weight gain, another important contributor. The human stomach produces two hormones that regulate appetite: ghrelin (which tells us to eat) and leptin (which tells us not to). H. pylori seems to lower ghrelin production in the stomach, Kamangar says. Considering the current obesity crisis, this has startling implications. “A generation of children are growing up without Helicobacter in their stomachs to regulate these two hormones,” says Blaser.
Like obesity and acid reflux, asthma was virtually unknown a century ago—and today, it’s common across the developed world. A recent study concluded that kids aged three to 13 who carry H. pylori are almost 59 per cent less likely to have asthma. What’s more, teens and kids were 40 per cent less likely to have hay fever and associated allergies, like eczema and rashes. Blaser, who co-authored the study, believes H. pylori could affect how a child’s immune system develops. An early encounter with Helicobacter, he suggests, could help their bodies learn to better respond to allergens, curbing the inflammation that triggers an asthma attack.
Blaser’s work follows on the heels of a study by University of Manitoba researcher Anita Kozyrskyj, published last year, showing that babies who received one or two courses of antibiotics before age one were 20 per cent more likely to have asthma by age seven. “With antibiotics, we’re changing our normal microbiota, including Helicobacter,” Blaser says. “Mothers, when you give antibiotics to your kid with an ear infection, there may be hidden, long-term costs.”
Will we be better off when H. pylori is gone for good? Dr. Karen Goodman, associate professor of epidemiology at the University of Alberta, is overseeing the Aklavik H. Pylori project. “It’s still quite a minority view that H. pylori infection might have some benefits,” she says. “The standard is, if the infection is detected in someone, that person should be offered treatment.” And the gains created by knocking out the bacteria can’t be taken for granted. “We used to see a duodenal ulcer every day,” says Canadian Digestive Health Foundation president Dr. Richard Fedorak, a professor of medicine at the University of Alberta, who’s also involved in the Aklavik project. “Now, we don’t see one for a week.”
Reached over the phone in Canberra, Nobel laureate Dr. Barry Marshall—one of the two Australian researchers who discovered H. pylori over 20 years ago and its role in gastritis and peptic ulcer disease—is even more explicit. “I’ve treated thousands of people with Helicobacter, and I don’t have any who’ve come back and said, ‘Dr. Marshall, I want it back please, I was healthier before,’ ” says Marshall (who famously drank the so-called “ulcer bugs” in a cocktail, to prove they caused ulcers). “They could do that,” he adds, “because I have all the strains in my refrigerator.”
