This study examines collagen (N=105) and apatite (N=65) data from an Imperial Roman skeletal sample from the necropolis of Isola Sacra (Rome, Italy). This paper explores correlations between the isotopic composition of bone samples and the inferred age and sex of these individuals (aged 5--45+ years). The collagen of males, and older individuals in general, was significantly enriched in (15)N but not (13)C. Bone carbonate was somewhat depleted in (13)C in some older individuals, suggesting increased consumption of olive oil and possibly wine. Subadults (>5 years) in the sample appear to have consumed an almost exclusively terrestrial diet. This study demonstrates a clear trend in dietary patterns between adult age groups, as well as between adults and children within a population.