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Study decoded · health · Emerging
Higher Vitamin C Intake Tied to More Islet Autoimmunity Risk in At-Risk Children
8,478 kids trackedNo protection foundHigher intake, more riskModerate intake lowest risk
A study of 8,478 genetically at-risk children published in the European Journal of Nutrition found that higher vitamin C intake did not lower the risk of islet autoimmunity, an early immune attack on insulin-producing cells, and was instead linked to a 4% higher risk of one autoantibody pattern for every 10 mg per 1,000 kcal increase in intake.
The TEDDY Study followed 8,478 children genetically at risk for type 1 diabetes from six clinical centers in the U.S. and Europe, checking diet and diabetes-related antibodies every 3 to 6 months for up to 10 years. Average vitamin C intake was 60.7 mg per 1,000 calories consumed. Over follow-up, 777 children (9.2%) developed islet autoimmunity, meaning their immune systems began attacking insulin-producing cells; 292 (3.4%) showed insulin antibodies first and 337 (4.0%) showed a different antibody called GADA first. Of those with islet autoimmunity, 319 (41.0%) went on to develop full type 1 diabetes. For every 10 mg per 1,000 kcal increase in vitamin C intake, risk of the insulin-antibody-first pattern rose 4% (hazard ratio 1.04). For the GADA-first pattern, children in the lowest third of vitamin C intake had 65% higher risk and those in the highest third had 42% higher risk, both compared with children eating moderate amounts.
The researchers describe this as a nonlinear, U-shaped pattern, where moderate vitamin C intake tracked with the lowest risk and both very low and very high intake tracked with higher risk. Vitamin C is an antioxidant nutrient the body cannot make on its own and must get from food, and the authors note that genetic variation in how the body transports and uses vitamin C could theoretically influence this relationship, though gene-related findings did not hold up after statistical correction for multiple comparisons. Vitamin C intake here was measured through food records rather than blood testing, differing from an earlier finding in the same cohort where higher blood levels of the vitamin tracked with lower risk of the insulin-antibody-first pattern.
GADA-First Autoimmunity Risk by Vitamin C Intake Tertile
Data Panel
- Who
- 8,478 genetically at-risk children across six centers in the U.S., Finland, Germany and Sweden, followed from birth to age 10
- Design
- Prospective observational cohort (TEDDY Study) with repeated dietary assessments every 3 to 6 months and Cox regression analysis, plus Bayesian sensitivity models
- Dose
- Mean total vitamin C intake 69.4 mg/day (energy-adjusted 60.7 mg per 1,000 kcal); intake assessed via 24-hour recall and repeated 3-day food records
- Primary result
- 777 children (9.2%) developed islet autoimmunity; insulin-antibody-first risk rose 4% per 10 mg/1,000 kcal increase in vitamin C (hazard ratio 1.04, 95% CI 1.00-1.07)
- Secondary
- GADA-first autoimmunity risk was 65% higher in the lowest third of intake and 42% higher in the highest third versus moderate intake; 319 of 777 children with islet autoimmunity (41.0%) progressed to type 1 diabetes; no association found between vitamin C and progression to diabetes itself
- Funding / conflicts
- Funded by the National Institutes of Health and the National Institute of Diabetes and Digestive and Kidney Diseases; no additional conflicts reported
This is an observational study in children already at high genetic risk for type 1 diabetes, so the findings describe an association, and results may not extend to children without that elevated genetic background. The study was funded by the National Institutes of Health and the National Institute of Diabetes and Digestive and Kidney Diseases.
Dr. Axe's Take
Parents of at-risk kids should not read this as a reason to load up on vitamin C tablets, and it is not a reason to avoid the nutrient either. Moderate intake tracked with the lowest risk while both very low and very high intake tracked with more risk, which fits my view that more is not automatically better with antioxidants. I would get vitamin C from real food, citrus, bell peppers, broccoli, strawberries, rather than high-dose supplements in young children, since food-based intake comes packaged with fiber and plant cofactors the body recognizes. For families with a history of type 1 diabetes, focus on whole foods and adequate vitamin D rather than fixating on one nutrient number.
— Dr. AxeDr. Axe Quiz