Cold dark matter particles with an intrinsic matter-antimatter asymmetry do
not annihilate after gravitational capture by the Sun and can affect its
interior structure. The rate of capture is exponentially enhanced when such
particles have self-interactions of the right order to explain structure
formation on galactic scales. A `dark baryon' of mass 5 GeV is a natural
candidate and has the required relic abundance if its asymmetry is similar to
that of ordinary baryons. We show that such particles can solve the `solar
composition problem'. The predicted small decrease in the low energy neutrino
fluxes may be measurable by the Borexino and SNO+ experiments.Comment: 4 pages, 3 figures (RevTex); Capture rate corrected to obey the
geometrical bound; Changes in adopted cross-sections and particle physics
motivation; Conclusions concerning helioseismology and solar neutrino fluxes
unchange