Baking soda change my hair colour?!?

So ive heard that if u make a paste of water + baking soda and apply that paste to your head as a shampoo it will clean the gunk that other products have created ( buildup) so i just tried it now and im wondering will it lighten/ change my haircolour??! Because i dont wanna take the towel off my head and find out i went from brown hair to blondE! Help! Has anyone tried this?! What will happen?!?