While more and more research is being done on celiac disease, there is still so much we don't know. A lot of what has yet to be uncovered deals with the risk factors associated with developing celiac disease.
Why do some people develop celiac while others don't? If someone is genetically predisposed to develop celiac, what influences whether or not they will have the disease?
A new study shines some light on this very topic and has discovered that the season you are born in, as well as your place of birth, may be risk factors attached to the future development of celiac disease.
Winter babies and people born in places with shorter days and less sunlight might have a lower risk of developing celiac disease than their peers born in warmer regions or seasons, a new Swedish study published in Archives of Disease in Childhood suggests.
There previously was some evidence to suggest this, as researchers have known that environmental and seasonal factors may play a role in the development of autoimmune diseases. It sounds puzzling to suggest that the month someone is born in could influence their development of an autoimmune disease, but it is what happens during those seasons, and not the seasons themselves, that are significant. Season and region of birth could be a proxy for other factors, such as vitamin D exposure and the incidence and frequency of viral infections.
To test out this idea, researchers examined data on almost 2 million children up to age 15 born in Sweden between 1991 and 2009, including 6,600 who had been diagnosed with celiac disease.
Overall, the risk of diagnosis was around 10 percent higher among children born in spring (March-May), summer (June-August) and fall (September-November) than it was among those born in winter (December-February). But interestingly, seasonal patterns differed by region.
The risk of celiac disease was higher among those born in the south of the country, where sunlight in the spring and summer is intense, than among children born in the north, where springs are colder and summers are shorter.
Additionally, the study found that children diagnosed before the age of 2 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 the summer or fall.
What Do These Findings Mean?
Because this study was observational, it doesn't provide causal evidence that certain seasons or birth regions can cause someone to develop celiac disease. So what can we learn from these results?
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 these factors could affect the immune system at a vulnerable time in its development. But that still wouldn't explain the regional variations, and these ideas need to be explored with more research.
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.
Regional differences in how much and what type of gluten infants eat might also may have contributed to study results, as could an influx of migrants in the southern part of the country who might have different eating habits.
One possible hypothesis regarding babies born in spring/summer months having a higher risk of celiac disease cites that these babies are more likely to be weaned and introduced to gluten during the autumn/winter, a time characterized by exposure to seasonal viral infections. Viral infections alter intestinal bacteria and increase the permeability of cells lining the gut, which could prompt the development of celiac disease.
Low levels of vitamin D exposure have previously been linked to immune related diseases, such as multiple sclerosis, inflammatory bowel disease, and type 1 diabetes.
Many factors are associated with the risk of contracting celiac disease and so far, research has not led to an understanding of the potential origin or cause of celiac disease. Currently, what we know is that celiac disease is associated with a genetic predisposition or a history of other autoimmune conditions, as well as a heightened risk among some ethnic groups. Learning more about other possible associations, like birth seasons and regions, may provide a better understanding both of the causes of celiac and at who has a greater risk of developing the disease.
Knowledge is Power
As always, the more you learn about Celiac disease, the better prepared you will be to live a healthy lifestyle. We recommend the reading Celiac Disease: A Hidden Epidemic whether your newly diagnosed or have been living gluten-free for years.