Alterations of body mass index and body composition in atomic bomb survivors.

Abstract

Obesity, underweight, sarcopenia and excess accumulation of abdominal fat are associated with a risk of death and adverse health outcomes. Our aim was to determine whether body mass index (BMI) and body composition, assessed with dual-energy X-ray absorptiometry (DXA), are associated with radiation exposure among atomic bomb (A-bomb) survivors. This was a cross-sectional study conducted in the Adult Health Study of the Radiation Effects Research Foundation. We examined 2686 subjects (834 men and 1852 women), aged 48-89 years (0-40 years at A-bomb exposure), for BMI analysis. Among them, 550 men and 1179 women underwent DXA in 1994-1996 and were eligible for a body composition study. After being adjusted for age and other potential confounding factors, A-bomb radiation dose was associated significantly and negatively with BMI in both sexes (P=0.01 in men, P=0.03 in women) and appendicular lean mass (P<0.001 in men, P=0.05 in women). It was positively associated with trunk-to-limb fat ratio in women who were less than 15 years old at the time of exposure (P=0.03). This is the first study to report a significant dose response for BMI and body composition 50 years after A-bomb radiation exposure. We will need to conduct further studies to evaluate whether these alterations affect health status.