  Magnetic field dependent corrections for the coupling constant of the
Nambu-Jona-Lasinio model are calculated by considering the one-loop background
field method. These coupling constants turn out to break chiral and flavor
symmetries and they lead to a slight improvement of the numerical values of the
up and down quark condensates when compared to results from lattice QCD. The
corresponding magnetic field dependencies of the neutral pion and kaon masses
are also presented and compared with available lattice QCD calculations. The
resulting magnetic field correction to the $\eta-\eta'$ mixing angle is also
estimated.
