Germs living in the gut may cause higher rates of allergies, chronic stomach upsets and even obesity among children living in rich countries, researchers reported.

They compared intestinal bacteria between children in Europe and the West African country of Burkina Faso, and found enough differences to help explain disparities in disease and obesity.

The findings, published in the Proceedings of the National Academy of Sciences, may support the development of probiotic products to help keep humans leaner and healthier, the researchers said.

“Our results suggest that diet has a dominant role over other possible variables such as ethnicity, sanitation, hygiene, geography and climate in shaping the gut microbiota,” Paolo Lionetti, of Italy’s University of Florence, and colleagues wrote. “We can hypothesize that the reduction in richness we observe in EU compared with Burkina Faso children could indicate how the consumption of sugar, animal fat and calorie-dense foods in industrialized countries is rapidly limiting the adaptive potential of the microbiota.”

The study builds on a body of evidence that human health relies heavily on the trillions of microorganisms living in and on our bodies. Only a fraction cause disease directly — many more help digest food, affect other bacteria and may influence hundreds of biological functions.

Recent studies have found that certain bacteria cause inflammation that can affect appetite as well as inflammatory bowel conditions like Crohn’s disease and colitis.

Lionetti’s team studied the DNA of the gut bacteria of children in Burkina Faso, who are breast-fed up to age 2 and eat a diet likely similar to that of Stone Age humans, with little meat. The Western diet, in contrast, is heavy in meat, processed grains, sugar and fat.

The researchers found that the African children had many bacteria to break down fiber, but the European children lacked those microbes. The ratios were similar to those found in studies comparing the gut bacteria of lean people to obese people.

This bacterial balance could even be causing obesity, the researchers said.

— Maggie Fox, Reuters