  By using a phenomenological field theory of nucleon-nucleon interactions,
Oberhummer et al. found a cross section of p+p $\to$ d + e$^+$ + $\nu _e$ about
2.9 times that given by the potential approach and adopted in Standard Solar
Model calculations. We show that a solar model with $S=2.9 S_{SSM}$ is
inconsistent with helioseismic data, the difference between model predictions
and helioseismic determinations being typically a factor ten larger than
estimated uncertainties. We also show that, according to helioseismology,
$\Sppzero$ cannot differ from $S_{SSM}$ by more than 15%.
