Vitamin and Mineral Deficiencies in Children with Autism
Children with autism spectrum disorder commonly exhibit deficiencies in vitamin D, folate, calcium, magnesium, iron, and zinc, with vitamin D and calcium deficiencies being nearly universal and most clinically significant.
Most Common Deficiencies
Based on the most recent systematic review and meta-analysis 1, children with ASD demonstrate significantly decreased intake and serum levels of:
Fat-Soluble Vitamins
- Vitamin D (most consistently deficient across all studies) 1, 2, 3
- Vitamin A 1, 3
- Vitamin E 1, 4
- Vitamin K 1
Water-Soluble Vitamins
- Folate (significantly lower than typically developing children) 2
- Vitamin B12 5, 4
- Thiamine, riboflavin, and niacin 1
Essential Minerals
Clinical Significance and Morbidity
The clinical consequences of these deficiencies are substantial. Co-deficiency of vitamins A and D has been shown to exacerbate core autism symptoms 3, with vitamin A and calcium levels negatively correlating with symptom severity 2.
Most concerning are the bone health complications: all four documented cases of serious bone conditions (rickets, vertebral compression fractures, osteopenia, slipped capital femoral epiphyses) in children with ASD and avoidant restrictive food intake disorder had calcium and vitamin D deficiency 5. Two of these four patients developed rickets specifically from vitamin D deficiency 5.
Underlying Mechanism
The deficiencies stem from significantly decreased protein intake 1 and severe feeding problems that are 5-fold more common in ASD 4. Children with ASD demonstrate:
- Increased food selectivity
- Resistance to new foods
- Reduced self-feeding ability
- Overall poorer diet quality compared to typically developing children 4, 6
These feeding behaviors result in statistically significant shorter stature in children with ASD (standardized mean difference: -0.16) 1, directly attributable to inadequate protein and micronutrient intake.
Priority Assessment
Screen specifically for:
- Vitamin D and calcium (highest risk for serious morbidity including rickets and fractures)
- Folate (consistently low and correlates with developmental scores)
- Iron and zinc (both significantly lower and correlate with Gesell Developmental Scale scores) 2
- Vitamins A, E, and B12
Important Caveat
While the AACAP practice parameter guidelines 7 comprehensively address autism diagnosis and comorbidities, they do not specifically address nutritional deficiencies—representing a significant gap in guideline coverage. The research evidence consistently demonstrates these deficiencies are common, clinically significant, and warrant routine screening, particularly given the documented cases of severe bone disease 5.
Vitamin D and calcium supplementation should be prioritized given the documented cases of rickets and fractures, with broader micronutrient assessment guided by feeding severity and growth parameters.