  We compute the strangeness and light-quark contributions Delta s, Delta u and
Delta d to the proton spin in nf=2 lattice QCD at a pion mass of about 285 MeV
and at a lattice spacing a approx 0.073 fm, using the non-perturbatively
improved Sheikholeslami-Wohlert Wilson action. We carry out the renormalization
of these matrix elements which involves mixing between contributions from
different quark flavours. Our main result is the small negative value MSbar
scheme value Delta s = -0.020(10)(4), at a scale mu = 7.4 GeV, of the
strangeness contribution to the nucleon spin. The second error is an estimate
of the uncertainty, due to the missing extrapolation to the physical point.
