  The effects of Wheeler's quantum foam on black hole growth are explored from
an astrophysical perspective. Quantum fluctuations in the form of mini (10^-5
g) black holes can couple to macroscopic black holes and allow the latter to
grow exponentially in mass on a time scale of ~10^9 years. Consequently,
supermassive black holes can acquire a lot of their mass through these quantum
contributions over the life time of the universe. This alleviates the need for
very efficient forms of baryonic matter accretion more recent than a redshift
z~6. Sgr A* in the Milky Way center is a candidate to verify this quantum
space-time effect, with a predicted mass growth rate of 4x10^-3 Mo yr^-1. A few
comments on the possibility and consequences of dark matter as quantum grown
black holes are made, with a big crunch fate of the universe.
