"For several years there has been controversy among scientists about whether vitamin D lowers the risk of developing of islet autoimmunity and type 1 diabetes," said Dr. Jill Norris, MPH, PhD, of the Colorado School of Public Health at CU's Anschutz Medical Center, corresponding author of the study.
By ‘islet autoimmunity,’ she was referring to the precursor to type 1 diabetes, which is detected by antibodies that appear when the immune system attacks the islet cells in the pancreas that produce insulin.
The report was published online ahead of the November print edition of the journal Diabetes, and looked at children enrolled in The Environmental Determinants of Diabetes in the Young (TEDDY) study.
A large sample size
Participants were children with an increased risk of type 1 diabetes based on their genes. They were screened and recruited in the US, Finland, Germany, and Sweden in 2004.
Since recruitment, the children had clinic visits every three months between three to 48 months of age, and then every six months thereafter. During these visits, blood samples were drawn to determine the presence of islet autoimmunity and vitamin D levels.
Researchers found 376 children who developed islet autoimmunity and compared them to the 1,041 who did not. Crunching data from these children’s blood samples, the researchers found that vitamin D levels in infancy and childhood were lower in those that developed islet autoimmunity later in life compared to those who did not.
Will supplementation help?
The study only looked at vitamin D levels and linked it to islet autoimmunity, and did not look at whether or not vitamin D intervention, whether with supplements or a diet, may have had any effect on the outcome.
However, it does echo similar studies that have been conducted in the past. For example, a 2013 study on 1,000 adult US military members found that participants with an increased intake of vitamin D in their adolescence had less risk of type 1 diabetes later in life.
"Since this association does not prove cause-and-effect, we look to future prospective studies to confirm whether a vitamin D intervention can help prevent type 1 diabetes," Dr. Norris said.
Published online ahead of print, https://doi.org/10.2337/db17-0802
“Plasma 25-Hydroxyvitamin D Concentration and Risk of Islet Autoimmunity”
Authors: Jill M. Norris, et al.