VITAMIN A IN BUTTER 



Prepared by the Bureau of Dairy Industry 



Vitamin A is essential for life and health in 

 people of all ages. Nutritionists and other 

 authorities generally recognize that butter is a 

 rich source of this essential vitamin. The total 

 ■vitamin A potency of butter depends on the 

 amount of colorless vitamin A it contains and 

 also on its carotene content. Carotene, the 

 substance which gives butter its natural yellow color, is converted 

 into vitamin A in the body. 



In order to answer certain practical questions raised by the 

 Food and Nutrition Board of the National Research Council 

 early in 1941 concerning the importance of butter as a source of 

 vitamin A in the diet of the people of the United States, the 

 agricultural experiment stations in 20 States, the Bureau of Dairy 

 Industry, and the Office of Experiment Stations inaugurated a 

 Nation-wide study of the vitamin A potency of the butter pro- 

 duced and marketed in different seasons of the year and in dif- 

 ferent regions. 



Prior to the survey it was recognized that the vitamin A potency 

 of milk, as well as that of the butter made from it, varied accord- 

 ing to the feed given the cows and that summer feeding conditions 

 differed from winter feeding conditions in most regions of the 

 country. Many investigators had shown that butter produced in 

 summer was generally much richer in both vitamin A and caro- 

 tene than butter produced in w T inter. But the actual vitamin A 

 potency of all the butter produced and sold in this country was 

 unknown, and no information was available to show the relative 

 amounts of summer and winter butter consumed by the average 

 person nor the time of year when the bulk of the summer or 

 winter butter was actually marketed or consumed. Such informa- 

 tion was wanted by the Food and Nutrition Board in order to 

 estimate how much vitamin A butter could be expected to furnish 

 in the human diet from month to month throughout the year. 



It is not essential that the day-to-day consumption of vitamin A 

 be the same as the recommended daily allowance. When more 

 vitamin A is consumed than is required for immediate use, the 

 excess is stored in the body and used later when the diet is 

 deficient in vitamin A. Possibly under ordinary circumstances an 

 adequate amount of vitamin A would be obtained if the average 

 daily intake from month to month approximated the recom- 

 mended daily allowance. Effort was made in this study, therefore, 



