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Finnish study connects infants' intestinal microbes to childhood diabetes

A study from the Aalto University finds that environmental factors such as the prevalence of antibiotics are part of what makes Finns the most likely in the world to contract Type I diabetes.

Vauvan käsi.
Babies need microbes to survive. Image: AOP

An Aalto University study published on Friday finds that the health of intestinal microbes in infants is connected to the development of childhood diabetes.

Researcher Tommi Vatanen says he had a pressing reason to take up the disease for his dissertation.

"The incidence of Type I diabetes is the highest in the world in Finland," Vatanen says. "But right across the border in Russian Karelia people suffer from it eight times less, even though Finns share a great deal of genetic background with people from the region. This was an indication that environmental factors play a large role."

Vatanen investigated the correlation between intestinal microflora and health using modern DNA studying methods. He focused mainly on Type I diabetes and other early onset autoimmune diseases.

"Hundreds of bacteria live in the intestine, and early childhood is an extremely important time for bacterial colonies to develop and prosper," Vatanen says.

Eastern divide

Vatanen's study is based on the hypothesis that infants who are not exposed enough to environmental microbes may experience disruptions in the development of their immune systems.

Supporting research looked into the effect of antibiotic regimens on the intestinal microbial flora of infants.

Autoimmune illnesses force the body's immune system to turn on itself. Genetic factors are behind the risk, but why do some people contract diabetes and some do not?

One of the biggest answers to this question was hinted at by the study, conducted with nearly 300 Finnish, Estonian and Russian children by studying their faeces during their first three years of life. All the subjects had a genetic predisposition to diabetes.

The first result was a surprise that opened many doors to solving the puzzle.

"The composition of the microflora in children's intestines was extremely different in Russian and Finnish infants," Vatanen explains. "Finnish subjects began to develop autoantibodies to Type I diabetes, meaning the disease's early symptoms. Russian children did not develop the antibodies at all, despite having the same risk."

Microbes teach the immune system

Vatanen's conclusion was that something in Finnish children's surroundings predisposes them to autoimmune illnesses. The Estonian infants' results were also eye-opening.

"A couple decades ago Type I diabetes incidence was very low in Estonia, but now it's almost as common as in Finland," Vatanen says.

A bacterial surface molecule called lipopolysaccharide (LPS) was a key difference. Finnish kids have much more of them than Russians, which is why Vatanen's team tested its link with diabetes.

"It is important in the first years of immune system development. In a way, intestinal microbes teach the body's immune system. If something goes wrong this early on, autoimmune diseases may become more common."

"Evolution in miniature"

Many other studies have shown that antibiotics wreak havoc on intestinal microbe colonies. Vatanen therefore decided to research the effects of antibiotic regimens.

His study included children who had been given 10 or more regimens during their first three years of life. The control group had ingested no antibiotics at all, and their microbe levels were far healthier.

"We also investigated the genetic code of the microbes, and found that only those microbes with a resistance to antibiotics remained and their genes multiplied. It's like an evolutionary process in miniature," Vatanen describes.

Vatanen says to keep in mind that intestinal microflora are extremely complicated, and that the technology to study them has been around for only a few years.

Edit: Changed name of Aalto University.

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