We report the first estimate of the He abundance of the population of RR Lyrae stars in the Galactic bulge .
This is done by comparing the recent observational data with the latest models .
We use the large samples of ab type RR Lyrae stars found by OGLE IV in the inner bulge and by the VVV survey in the outer bulge .
We present the result from the new models computed by Marconi et al .
( 2017 ) , showing that the minimum Period for fundamental RR Lyrae pulsators depends on the He content .
By comparing these models with the observations in a Period versus effective temperature plane , we find that the bulk of the bulge ab type RR Lyrae are consistent with primordial He abundance Y = 0.245 , ruling out a significant He-enriched population .
This work demonstrates that the He content of the bulge RR Lyrae is different from that of the bulk of the bulge population as traced by the red clump giants , that appear to be significantly more He-rich .