"Vitamin butter" refers to a product that combines vitamins with butter, which can be used as a spread on food. It provides additional nutrients from the vitamins while retaining the creamy texture and taste of butter. Full definition
How often does the cod liver oil with high vitamin butter oil need to be taken since they are fat soluble? (holisticsquid.com)
He brought with him two things — a bottle of cod liver oil and a bottle of high vitamin butter oil from cows eating growing grass. (westonaprice.org)
They make a great product also where they combine this with high Vitamin Butter Oil, so you have plenty of options with this vitamin as well. (fitnessandpower.com)