As countries in the northern hemisphere prepare for the low vitamin D season, those months during which the sun’s rays are too low to stimulate the production of this vitamin in the skin, a study explains why a deficiency in vitamin D early in life is associated with greater vulnerability to autoimmune diseases.
During childhood, the thymus helps immune cells differentiate body tissues from dangerous intruders. A research team found that at this stage of life, vitamin D deficiency leads to aging premature thymus.
“An aging thymus causes “leaks” in the immune system, explains John White, lead author of the study and director of the Department of Physiology at theMcGill Universitywhere he teaches. The thymus then loses its effectiveness in filtering immune cells that may attack healthy tissues by mistake, which increases vulnerability to autoimmune diseases, such as type 1 diabetes.”
Scientists have known for years that vitamin D contributes to the absorption of calcium, which strengthens bones, and more recent research has revealed the vitamin’s essential role in regulating the immune system, says Professor White.
“Our study clarifies this role and could lead to new strategies for preventing autoimmune diseases.”
Although the work was carried out on mice, its conclusions are nevertheless relevant for humans, because the thymus functions similarly in both species, he adds.
The importance of a complementary contribution
Published in Science Advancesthe study highlights the importance of adequate vitamin D intake, particularly in children.
“In cities like Montreal, where the production of vitamin D from the sun ceases between the end of autumn and the beginning of spring, the supplementation is essential, argues Professor White. If you have a young child, it is important to consult a healthcare professional to ensure that its consumption is sufficient.”
This breakthrough builds on a 2001 Finnish study, in which more than 10,000 children were followed, which found that those who received a vitamin D supplement early in life were up to five times less likely to get type 1 diabetes later in life.
Finland, where the natural production of vitamin D is interrupted for long periods, was the ideal place to study the multiple roles of this nutrient, notes John White.
As part of the McGill study, scientists conducted tests on mice unable to produce vitamin D to examine the effects of this deficiency on the thymus: using cellular analyzes and sequencing of gene, they were able to see the repercussions on the immune system.
In future studies, Professor White plans to analyze the effects of vitamin D on the human thymus – a subject that has not yet been addressed, he argues.
The study was funded by the Canadian Institutes of Health Research and the Canadian Genomics Enterprise.
