I remember Guinness being prescribed for "general debility" in some hospitals. In severe cases we could whisk an egg and blend it into the stout - revolting! I've Heard the term "invalid stout" used in the same context. It may have had something to do with those advertising Campaigns such as "Guinness is good for you". I remember that phrase was exchanged, at least in the nursing profession, for "There's a baby in every bottle" owing to the increasing birthrate during those years.