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 About one in 100 people have celiac disease, an autoimmune disorder
that damages the small intestine and interferes with the absorption
of nutrients from food. People with celiac disease can't tolerate
gluten, a protein in wheat, rye and barley. Left untreated, the
condition can lead to complications such as malnutrition, low bone
density, lactose intolerance and infertility.
While the exact causes of celiac disease are unknown, some previous
research has pointed to the potential for the season of one’s birth
to be among many environmental factors that might influence the
risk, said lead study author Fredinah Namatovu, a public health
researcher at the Umea University in Sweden.
“Season of birth and area of birth appears to play a role,” Namatovu
said by email. “Season and region of birth could be a proxy for
other factors such as vitamin D and viral infections.”
To test out this idea, researchers examined data on almost 2 million
children up to age 15 born in Sweden from 1991 to 2009, including
about 6,600 diagnosed with celiac disease.
Overall, the risk of diagnosis was around 10 percent greater among
children born in spring (March-May), summer (June-August) and autumn
(September-November) than it was among those born in winter
(December-February). But seasonal patterns differed by region, the
researchers report in Archives of Disease in Childhood.
The risk of celiac disease was higher among those born in the south
of the country, where sunlight in spring and summer is intense, than
among children born in the north of the country, where springs are
colder and summers shorter.
In another twist, kids diagnosed before age of 2 years appeared to
have a greater risk if they were born in the spring, while older
children seemed to have an increased risk if they were born in
summer or fall.
Because the study is observational, it can’t prove that certain
birth seasons or regions directly cause celiac disease, the authors
note.
Potential explanations for the variations in risk might be seasonal
differences in exposure to viral infections, or to vitamin D, which
the body makes in response to sunlight, both of which could affect
the immune system at a vulnerable time in its development. But that
wouldn’t explain the regional variations and these ideas would need
to be explored with more research, the authors conclude.
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Among other things, global warming, variation in the type of spring
weather and the timing of changing seasons could potentially explain
some of the differences in risk found in the study, said Dr. Joseph
Murray, director of the celiac disease program at the Mayo Clinic in
Rochester, Minnesota.
Trends in how much and what type of gluten infants eat over time
might also have contributed to the study results, as could an influx
of migrants in the southern part of the country who might have
different eating habits, Murray, who wasn’t involved in the study,
added by email.
“Many factors are associated with the risk of contracting celiac
disease and thus far, research has not led to an understanding of
the potential cause or origin of the disease,” said Dr. Alex Krist,
a researcher at Virginia Commonwealth University in Richmond who
wasn’t involved in the study.
“Our current understanding of who is at risk is limited to people
who have a family history or other autoimmune conditions, as well as
those belonging to certain racial and ethnic groups,” Krist added by
email. “Learning more about other potential associations, like birth
season, may prove useful in better understanding both the cause of
and who is at risk for celiac disease."
SOURCE: http://bit.ly/2b9IPcq Archives of Disease in Childhood,
online August 15, 2016.
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