Nutrition, physical activity, and bone mineral density in youth with autistic spectrum disorders

Fractures and pain, secondary to low bone mineral density (BMD), have been reported in pediatric patients with autistic spectrum disorders (ASD). The purpose of this study was to assess the BMD of a clinical sample of 10- to 18-year olds with ASD, and the nutrition and physical activity correlates of skeletal health in this population.

Twenty-six patients with ASD were recruited from an outpatient multidisciplinary child-development clinic. Lumbar bone density was measured using dual-energy x-ray absorptiometry. Data collection included anthropometries, serum nutrient levels, parent interview, and 72-hour diet, screen-time, and physical activity records.

Four patients (15%) met criteria for pediatric low BMD with z scores less than or equal to -2.0; another 4 were at risk with z scores less than or equal to -1.0. Approximately 54% of participants had insufficient serum 25-hydroxy vitamin D. Mean electronic media use was 251 minutes/day; mean physical activity 69 minutes/day. Fewer than 50% of participants met daily reference intake of vitamins A, B3, D, E, K, zinc, calcium, folate, potassium, and fiber. Bone density correlated positively with body mass (r = .47), calcium intake (r = .46), and calorie intake (r = .58).

Children aged 10 to 18 years old with ASD are at risk for occult low bone density. In this study, those with low body mass index and insufficient calcium and calorie intake were at greater risk. Other unhealthy behaviors in this population included a high screen-time to physical activity ratio and multiple nutrient deficiencies.