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In Finland, increased vitamin D levels may have impacted type 1 diabetes incidence

Posted on: August 2, 2014   by  Jeff Nicklas


Researchers recently measured vitamin D levels among Finnish children in order to find support for the hypothesis that increased vitamin D status from food fortification in Finland may have lent to a leveling off of type 1 diabetes incidence.

Finland, a northern country sitting at latitude of 64⁰ North, has the highest incidence rates of type 1 diabetes (T1D) in the world.

T1D is a complex autoimmune disease common in children in which the body’s immune system mistakenly attacks its own beta-cells, which are the pancreatic cells responsible for producing insulin. This leads to the body’s inability to produce enough insulin to help shuttle glucose into cells from the bloodstream.

Last year, it was found that after 2006, rates of T1D were reduced and remained relatively constant in Finland. At the time, researchers hypothesized that an increase in vitamin D-fortified foods in 2003 could have played a role in this change.

Recently, Dr. Marjaana Mäkinen and colleagues conducted a study to attempt to add evidence to this hypothesis.

They looked at serum samples of 387 children from the Diabetes Prediction and Prevention (DIPP) Study. The DIPP Study is an ongoing study that began in 1994 to determine factors that could help predict and prevent the progression of T1D.

The serum samples were first collected when the children were 3 months of age, and were taken every three or six months after. The researchers measured vitamin D levels from samples taken between 1998 and 2002 and compared them to levels measured from samples collected between 2003 and 2006.

Considering that rates of T1D plateaued after 2006, the researchers were interested in if there was an increase in vitamin D status leading up to this which could help explain the change in rates and to add evidence to vitamin D’s potential role in T1D.

Here is what the researchers found:

  • Average vitamin D levels in 2003-2006 were 33.96 ng/ml compared to 27.72 ng/ml in 1998-2002 (P < 0.001).
  • During 1998-2002, 69.9% of children had vitamin D levels lower than 20 ng/ml compared to 37.3% of children in 2003-2006.
  • Children younger than 2 years of age had significantly higher vitamin D levels than children older than 2 years.

The researchers stated,

“In conclusion, our findings show that the increased 25(OH)D concentrations observed since 2003 in Finnish children have a delayed temporal association with the reversal of the rising trend in the incidence rate of type 1 diabetes after 2006.”

The researchers note that since they didn’t have data on vitamin D intake, they cannot say for certain what main factors were that drove the increase in vitamin D status. Furthermore, the design of the study prevents the ability to say whether the increase in vitamin D levels caused a leveling off of T1D incidence.

This study presents intriguing evidence for vitamin D’s role in T1D because of the delayed temporal correlation observed between increased vitamin D status and decreased T1D incidence.

If future additional vitamin D supplementation programs are implemented in Finland, researchers can continue to see the effects of long-term supplementation on trends in T1D incidence.


Mäkinen, M. et al. An Increase in Serum 25-Hydroxyvitamin D Concentrations Preceded a Plateau in Type 1 Diabetes Incidence in Finnish Children. Journal of Clinical Endocrinology and Metabolism, 2014.

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