http://well.ca/products/rougier-epsom-salts_8064.html
It is specifically formulated for oral use. It should be available at pharmacy counters in supermarkets and stores.
For the olive oil it needs to say "Extra Virgin" and nothing else. The basic supermarket brands, e.g. "BERTOLLI" as you're mention it already, is a starting point and here is a picture of theirs. It simple states it is for salads and dressings.
Other brands are available.