Antioxidant-Rich Diet May Reduce Helicobacter pylori Risk

Carolyn Crist

September 23, 2022

People who eat a balanced diet with sufficient antioxidants from fruits and vegetables may face reduced risks for Heliobacter pylori infections, according to a new report.

In particular, patients with an H pylori infection were more likely to score lower on the Dietary Antioxidant Index (DAI), which was created to consider a diet's entire antioxidant profile.

"Available evidence indicates that diet has an important role in developing H pylori infection. Therefore, protective dietary factors are important from a public health point of view," Farzad Shidfar, a professor of nutrition at the Iran University of Medical Sciences and member of the university's Colorectal Research Center, and colleagues write.

"While some nutritional research has widely focused on single nutrients or foods in diet-disease relations, the overall diet could be more informative because humans typically consume a combination of nutrients and foods," they write. "Dietary indices such as DAI are one of the approaches for this purpose."

The study was published online in BMC Gastroenterology.

Measuring Antioxidant Intake

Previous research has indicated an inverse association between the DAI and inflammatory diseases, the study authors write, including gastric cancer, colorectal cancer, nonalcoholic fatty liver disease, and obesity. Studies have also indicated that H pylori infection is related to deficiencies in vitamins A, C, and E, which have antioxidant properties.

In a case-control study, the research team compared the dietary intake of 148 patients with H pylori to 302 healthy controls without infection. The patients in the H pylori–positive group were recruited between June 2021 through November 2021 from the gastroenterology clinic at Rasoul-e-Akram Hospital in Tehran, where they were newly diagnosed with active infection and not yet under treatment.

The researchers calculated the DAI based on dietary intake information from a validated, 168-item food frequency questionnaire used in Iran. The participants were asked about their dietary intake based on the average day, week, month, and year. They also discussed serving sizes of food items, and to increase the accuracy of estimates, interviewers showed household measurements or serving sizes to confirm the measurements with participants.

The average age of the study participants was 39 years, and about 60% were women. Compared with the healthy controls, those with H pylori were significantly older, had higher body mass index, and smoked more.

Overall, patients with H pylori had a significantly lower intake of vitamin A, vitamin E, manganese, and selenium. Other differences in dietary intake — for vitamin C and zinc — were not significant.

The average total DAI was significantly higher in the healthy controls, at 7.67, as compared with 3.57 in the patients with H pylori. The risk for infection decreased as continuous DAI increased.

After adjusting for several variables, the researchers found that participants with less than the median DAI values had an increased risk of developing an H pylori infection.

"A balanced diet, especially high consumption of fruits and vegetables, might protect people against the consequences of H pylori infection," the study authors write. "On the contrary, a diet full of carbohydrates and sweets is related to a higher H pylori infection prevalence."

Why a Good Diet May Help Combat Infection

The findings are consistent with other studies that have noted a higher intake of fruits and vegetables among healthy people compared with those who have H pylori infections, the study authors write. Animal studies have also indicated that taking vitamins A, C, and E and selenium can lead to a reduction in H pylori growth.

"Several biologically plausible reasons may explain why dietary antioxidants might be, either directly or indirectly, a protective factor against H pylori infection," the researchers write. "It is well-known that antioxidants, with their free radical scavenging activities, can inhibit the growth of H pylori."

H pylori is urease-positive and can synthesize a large amount of urease for ammonia production to neutralize gastric acid, which allows it to colonize in the stomach epithelium, the study authors write. Vitamin C inhibits urease activity and improves the stimulation of granulocytes, macrophages, lymphocytes, and immunoglobulin production. Other nutrients, such as zinc, may inhibit the urease enzyme and prevent H pylori adhesion to gastric tissues, they write.

Richard Peek, Jr., MD

"Dietary elements have previously been shown to dramatically alter pathogenic responses to H pylori infections," Richard Peek, Jr., MD, professor of medicine and director of gastroenterology at Vanderbilt University Medical Center, told Medscape Medical News.

Peek, who wasn't involved with this study, and colleagues found that iron deficiency is linked with altered bile metabolism, which can promote H pylori–induced gastric carcinogenesis.

"The current study is important, as it suggests that shifting to a diet rich in antioxidants may be beneficial in terms of H pylori infection," he said.

At the same time, Peek expressed caution about generalizing the results across populations.

"Most of the persons enrolled in this study were likely infected with H pylori as children," he noted. "Therefore, the inverse role of antioxidant-rich diets and H pylori infection must be interpreted with caution."

Future studies should confirm the findings in other groups and determine whether antioxidant-rich diets limit the diseases caused by H pylori infection, Peek added.

The study was not funded by any research center, and the authors declared no conflicts of interest. Peek reported no relevant disclosures.

BMC Gastroenterol. Published online September 6, 2022. Full text

Carolyn Crist is a health and medical journalist who reports on the latest studies for Medscape, MDedge, and WebMD.

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