Latitude, urbanization, age, and sex as risk factors for vitamin D deficiency disease in the Roman Empire

OBJECTIVES: The aims of the study are to investigate the effects of latitude, settlement type, age, and sex on the prevalence of vitamin D deficiency disease in the Roman Empire using human skeletal remains from cemetery sites (1st to 6th cent. AD). MATERIALS AND METHODS: Data from 2,787 individuals (1,143 subadults, 1,644 adults) from 18 cemeteries associated with 15 different settlements in the Mediterranean and north-western Europe were analyzed. Vitamin D deficiency disease (rickets, osteomalacia) was identified using standard paleopathological criteria. Multivariate statistical analysis was used analyze the effects of the variables of interest on the prevalence of vitamin D deficiency. RESULTS: The overall prevalence of rickets in subadults (<20 years) was 5.7%, and 3.2% of adults showed osteomalacia and/or residual rickets. There was a positive association between rickets in subadults and latitude, with numerous cases of rickets among infants. There was no general association with sex or settlement type, although an elevated prevalence of rickets was observed at a cemetery associated with a settlement (Ostia, Italy), which had multi-storey buildings. DISCUSSION: The association of rickets with latitude may reflect care practices that, in more northerly locations where solar radiation is less intense, placed infants at increased risk of insufficient sunlight exposure to permit adequate vitamin D biosynthesis. The elevated level of vitamin D deficiency at Ostia may reflect, at least in part, the lack of sunlight due to dense occupation of multi-storey blocks that prevented direct sunlight from reaching living quarters and the streets between these closely spaced buildings.