  In the framework of Randall -- Sundrum theory with extra dimension Reissner
-- Nordstr\"om black hole solutions with a tidal charge have been found. The
shadow around the supermassive black hole in M87 was reconstructed in 2019
based on observations with the Event Horizon Telescope (EHT) in April 2017. In
May 2022 the EHT Collaboration presented results of a shadow reconstruction for
our Galactic Center. Earlier, for Reissner -- Nordstr\"om metric we derived
analytical expressions for shadow size as a function of charge and later
generalized these results for a tidal charge case. We discuss opportunities to
evaluate parameters of alternative theories of gravity with shadow size
estimates done by the EHT Collaboration, in particular, a tidal charge could be
estimated from these observations.
