Vitamin C and type 1 diabetes in children: is the middle the safest place?

The TEDDY study follows children with a genetic risk of type 1 diabetes from infancy, testing every three to six months for islet autoantibodies, the immune markers that usually appear before the disease. An analysis published in the European Journal of Nutrition on 24 September 2026 looked at how much vitamin C 8,478 of these children got from their diet over time.

777 children (9.2%) developed islet autoimmunity, and 319 of them went on to type 1 diabetes. Average vitamin C intake was 60.7 mg per 1,000 kcal. Higher intake was slightly linked with a higher risk of one type of autoimmunity, where insulin autoantibodies appear first (hazard ratio 1.04 for every extra 10 mg per 1,000 kcal). For the other type, where GAD autoantibodies appear first, both the lowest and the highest thirds of intake carried more risk than the middle third (hazard ratios 1.65 and 1.42).

The authors' conclusion is cautious: vitamin C intake was not consistently associated with autoimmunity or with progression to type 1 diabetes, though the pattern with the lowest risk at moderate intakes merits more study. Links with vitamin C-related gene variants did not hold up after correcting for multiple tests. For parents this is no reason to add or cut supplements; a varied diet with fruit and vegetables remains the advice.