Nutrition and Bone Density in Boys with Autism Spectrum Disorder.

Background: Boys with autism spectrum disorder (ASD) have lower bone mineral density (BMD) than typically developing controls. Differences in diet and exercise may contribute to low BMD.

Objective: Our aim was to examine macro- and micronutrient intakes and self-reported physical activity in boys with ASD compared to TDC and the relationship of these variables with BMD.

Design/methods: We conducted a cross-sectional study of 49 boys (25 ASD, 24 typically developing controls) assessed for 3-day food records and physical activity records, and BMD of the whole body less head, hip, and spine using dual-energy x-ray absorptiometry. Fasting levels of 25(OH) vitamin D and calcium were obtained.

Participants: Participants were adolescent boys, aged 8 to 17 years, recruited from a clinic population (ASD) or community advertisements (ASD and typically developing controls) matched for age.

Results: ASD participants were approximately 9 months younger than typically developing control participants on average. Body mass index and serum vitamin D and calcium levels were similar. Boys with ASD consumed 16% fewer calories, with a larger percentage obtained from carbohydrates, and 37% less animal protein and 20% less fat than typically developing controls. A lower proportion of ASD participants were categorized as "very physically active" (27% vs 79%; P<0.001). BMD z scores were 0.7 to 1.2 standard deviations lower in ASD than typically developing controls at all locations. Higher animal protein, calcium, and phosphorus intakes were associated positively with bone density measures in boys with ASD.

Conclusions: Compared to typically developing controls, boys with ASD had lower protein, calcium, and phosphorus intakes, activity levels, and BMD z scores at the lumbar spine, femoral neck, total hip, and whole body less head. Protein, calcium, and phosphorus intakes were associated positively with BMD.