These data include carbon, oxygen and clumped isotope compositions of shells of natural populations of three land snail species (Clausilia pumila, Succinella oblonga and Trochulus hispidus) across Europe. δ¹³C, δ¹⁸O and Δ₄₇ values of snail shells from field-collections were determined in two laboratories (Institute for Nuclear Research, Debrecen, and Geological Institute, ETH Zürich) using IRMS. Detailed analysis and interpretations of the results obtained can be read in the original publication.