Unsalted butter is categorized as a mild alkaline while regular salted butter is categorized as being highly acidic, although with most soft drinks, meat, fish, and eggs. Those who have problems with acid reflux/heartburn will definitely want to avoid consuming highly acidic foods and drinks such as butter.
There are certainly other reasons to stay away from butter if you are trying to stay healthy, such as the sheer amount of saturated fat which it contains. Although many people may not think of butter as being a very acidic food, it is indeed and can aggravate acid reflux in those who already have problems with it.
I have been canning butter and storing it in my pantry. Salted butter, being considered highly acidic could therefore be water bathed instead of pressure canned, because it is acidic ? I’m thinking yes, but I need someone else to confirm.