  It is shown that hyperon beta decay data can be well accommodated within the
framework of Cabbibo's SU(3) symmetric description if one allows for a small
SU(3) symmetry breaking proportional to the mass difference between strange and
nonstrange quarks. The F/D ratio does not depend sensitively on the exact form
of the symmetry-breaking, and the best fits are close to the value previously
used in the analysis of deep inelastic scattering of electrons or muons on
polarized nucleons. The total quark helicity and strange quark polarization in
the nucleon are discussed.
