  We investigate the application of the distillation smearing approach, and the
use of the variational method with an extended basis of operators facilitated
by this approach, on the calculation of the nucleon isovector charges
$g_S^{u-d}$, $g_A^{u-d}$, and $g_T^{u-d}$. We find that the better sampling of
the lattice enabled through the use of distillation yields a substantial
reduction in the statistical uncertainty in comparison with the use of
alternative smearing methods, and furthermore, appears to offer better control
over the contribution of excited-states compared to use of a single, local
interpolating operator. The additional benefit arising through the use of the
variational method in the distillation approach is less dramatic, but
nevertheless significant given that it requires no additional Dirac inversions.
