  The breaking of flavor SU(3) symmetry in the axial couplings and magnetic
moments of baryons is analyzed in the $1/N_c$ expansion. A simple meson loop
graph which is known to be of order $\sqrt{m_s}$ and leading order in $1/N_c$
correctly predicts the pattern of symmetry breaking in the magnetic moments. It
is, however, not possible to use this graph to predict the magnitude of the
breaking. The situation with the axial couplings is less clear. In this case
the breakings are relatively small and do not appear to follow an obvious
pattern. Nevertheless there is a clear indication that, with symmetry breaking
taken into account, the F/D ratio (defined in the presence of SU(3) breaking)
is considerably less than the SU(6) value of 2/3. With sizeable uncertainty, we
find F/D \approx 0.44. The quantity 3F-D which is relevant for the analysis of
spin-dependent deep inelastic scattering is considerably smaller than the SU(6)
value of unity. The new value, 3F-D=0.27+-0.09, is consistent with vanishing
strange-quark spin in the nucleon.
