  We investigate the theoretical and observational implications of the
acceleration of protons and heavier nuclei in supernova remnants (SNRs). By
adopting a semi-analytical technique, we study the non-linear interplay among
particle acceleration, magnetic field generation and shock dynamics, outlining
a self-consistent scenario for the origin of the spectrum of Galactic cosmic
rays as produced in this class of sources. Moreover, the inferred chemical
abundances suggest nuclei heavier than Hydrogen to be relevant not only in the
shock dynamics but also in the calculation of the gamma-ray emission from SNRs
due to the decay of neutral pions produced in nuclear interactions.
