The application of biomolecular techniques for the study of food practices in the Italian Bronze Age has revealed an interesting complexity. This is particularly true for the Po plain, in northern Italy, where the use of “alternative” grains (i.e., the millets) has been assessed isotopically through the measurement of stable carbon (δ13C) and nitrogen (δ15N) isotope ratios in human and animal bone collagen at the site of Olmo di Nogara (Verona). This work provides new isotopic data from 12 Early, Middle, and Late Bronze Age sites from western Veneto and Friuli. Data obtained contribute to the understanding of mode and tempo of the spread of new crops in northeastern Italy, which appears to be a hotspot for the study of Bronze Age farming economies in Europe. We have successfully analyzed 146 specimens to find that δ13C values are higher, in a way that we interpret as indicative of C4 plant consumption. Four of the sites analyzed, with a specific chronological indication, show this evidence. We explain this phenomenon as the result of a discontinuous spread of new crops in northeastern Italy at a very specific moment of the Bronze Age. The data presented might call for a reconsideration of food production and consumption among Bronze Age groups of southern Europe.