Children's autoimmune diseases (T1D, thyroid, celiac, JIA) linked to low vitamin D and cofactors - review

Endocrine–Immune Crosstalk in Pediatric Autoimmune Diseases: A Systematic Review of the Role of Micronutrients, with Emphasis on Vitamin D

Nutrients (MDPI), 24 September 2026, https://doi.org/10.3390/nu18193148

Atapattu Navoda, Sunil J. Wimalawansa

Summary by Claude Opus 5.5 - September 2026

Takeaway: This review argues that low vitamin D, often alongside low magnesium, zinc, selenium and omega-3, weakens immune tolerance in children and raises the risk of autoimmune diseases such as type 1 diabetes, Hashimoto's and Graves' thyroid disease, celiac disease, juvenile idiopathic arthritis and Addison's disease. The authors recommend keeping blood 25(OH)D above 40 ng/mL, and preferably 50–80 ng/mL.

Study type: A review of 404 publications (1990–May 2026) by a Sri Lankan pediatric endocrinologist and Sunil Wimalawansa. It is labeled a systematic review, but the results are a narrative synthesis with no pooled numbers.

Dosing proposed (daily vitamin D3, by body weight):

Non-obese (BMI <29): 70–90 IU/kg. For example, a 30 kg child would take about 2,100–2,700 IU/day.
Moderately obese (BMI 30–39): 100–130 IU/kg.
Morbidly obese (BMI 40+): 140–180 IU/kg.

For severe deficiency, the authors' clinical figure suggests a loading dose of 50,000 IU weekly for 3–6 weeks, then maintenance. It pairs D3 with vitamin K2 (MK-7) and magnesium. The authors say toxicity appears only above about 150 ng/mL, and they call the 400–600 IU/day pediatric guidelines far too low.

The authors blame conflicting trial results on poor design: trials that "recruit vitamin D-sufficient subjects," use too-low doses, or never measure the achieved 25(OH)D.

What this does NOT show / limitations:

No new data. Most of the evidence is observational or mechanistic, which shows association, not that vitamin D prevents these diseases in children.
It reports no pediatric RCT that achieved 50–80 ng/mL and measured autoimmune outcomes.
The weight-based doses are the senior author's own formulas, not trial-tested in children.
The parallel rise in vitamin D deficiency and childhood autoimmunity is a population-level trend, not proof of cause.
Cofactor benefits (zinc, selenium, omega-3) are supported mainly by mechanism.