Human-driven landscape change, particularly urbanization, is reshaping pollinator communities,  yet the functional traits that mediate species persistence remain poorly understood. Dietary specialization is commonly used to predict species vulnerability. However, conventional measures based  on taxonomic host breadth may not reflect pollinators’ actual nutritional needs, especially in cities where exotic and native plants coexist. Because insects cannot synthesize sterols de novo, they must obtain these essential lipids from their diet, making sterol requirements a critical and over- looked axis for understanding pollinator persistence. Here, we analyzed 22 sterols in 274 nest pollen samples and 1,267 bee individuals from four common wild bee species, ranging from specialists to generalists, across five European cities. We reveal that regardless of host-plant specialization levels, all species relied on a shared set of four abundant sterols, commonly found in floral pollen, suggesting that nutritional generalization may contribute to their urban persistence. Nonetheless, the full sterol profiles, considering both composition and relative abundance, varied across species and cities. The most specialized bee, Chelostoma florisomne, showed more uniform sterol use and lower occurrence in highly urbanized areas, possibly due to frequent mowing of its main host, Ranunculus flowers. These findings underscore the limitations of taxonomy-based approaches in predicting pollinator responses to urbanization and highlight the importance of nutritional traits, such as sterols, in shaping ecological niches and guiding conservation strategies.