I am making a Red Velvet cake and cannot seem to find regular buttermilk - only the lowfat. Is this ok?
Techinically all real buttermilk is low fat as it is the residue from the buttermaking process. All full fat buttermilks are cultured (as are many of the low fat buttermilks sold in grocery stores). If your recipe is just calling for buttermilk then it is not a substitute if you use something marked low fat buttermilk.
The reall difference in buttermilk is whether it is cultured (like taking milk and adding a souring agent like vinegar to it) or whether it the stuff from the butter making process.