In this cohort of 89 Caucasian males aged 4 to 8 years old, no differences were observed in the concentrations of 25(OH)D between participants with ASD and controls, and no effect of a casein-free diet was observed within the participant group (). Fifty-four children in the entire cohort (61%) had concentrations of less than 20ng/mL. This is the minimum concentration recommended by the American Academy of Pediatrics to ensure good bone health.8
For pre-pubertal children this is a critical deficiency that can have sequelae throughout the rest of their lives. The peri-pubertal period is a time of rapid bone development and remodeling when an individual acquires peak bone mass.9
Vitamin D deficiency has become a major health concern in our current society where sunblock and indoor activities have limited sun exposure for children, and dietary sources cannot make up the difference. Results of this study provide additional evidence to support that concern. We expected 25(OH)D concentrations to vary by season of enrollment since exposure to sunlight is so important for vitamin D synthesis, but this expected difference by season was not observed. This could simply be a function of sample size, since the study was not designed to detect this difference. However, this finding could also represent effective use of sunblock during warmer months, keeping the measured 25(OH)D values lower.
Children with ASD in this study were no more likely than their matched controls to have a low 25(OH)D concentration. These results must be interpreted in light of the limitations of the control group. The control children were likely to have had some degree of inflammation which could affect 25(OH)D concentration. They were, however, carefully screened and excluded for steroid use or sleep apnea that might contribute to alterations in growth patterns.
The majority of children in this cohort, participants and controls, had low concentrations of 25(OH)D. This finding should be of concern to all providers of medical care to children, but especially to those managing the care of children with ASD. These children may be at risk of additional threats to calcium homeostasis and bone health as they age. Opportunities for active weight-bearing exercise in sunlight can be limited for children with ASD. At least a quarter of children with ASD will also have chronic gastrointestinal symptoms10
that could also have an impact on calcium absorption. In addition, up to 46% of them are likely to be diagnosed with co-occurring epilepsy.11
Treatment with certain antiepileptic drugs, including valproic acid, is associated with reduced bone mineral density.12
As children with ASD age into adulthood they will be confronted by general chronic health issues such as osteoporosis that affect any aging population. However, these additional medical problems will present greater challenges in people with ASD. We need to better understand the risks and potential preventive measures that can be taken for those individuals while they are still children.
What this paper adds
- Children with and without ASD have low plasma concentrations of 25(OH)D
- 25(OH)D concentrations do not differ between children with ASD and typically developing controls