Many member states currently require the mandatory addition of vitamins A and D to margarine and fat spreads for reasons of public health. Voluntary fortification of margarine with vitamins had been practiced by manufacturers since 1925, but in 1940 with the advent of the war, certain governments took action to safeguard the nutritional status of their nations by making the addition of vitamin A and D compulsory. This mandatory fortification was justified in the view that margarine was being used to replace butter in the diet.