Food sources
Thiamin is widely distributed in a large variety of animal and vegetable tissues, but there are few foods in which it occurs in abundance. This is strikingly emphasized in Figure which shows the thiamin content of average servings of some common foods. Obviously, several servings of even the better sources of thiamin are needed to meet the recommended allowance. Therefore, enrichment of bread and cereals was instigated to make iteasier for the average person to meet his requirement economically. Because bread constitutes about one-fifth the calories the average American diet and only a very illlall fraction of the bread consumed in this country is made from whole wheat, the enrichment of white flour and bread with thiamin, riboflavin, niacin, and iron was a logical step. On the basis of the average per capita consumption offlour and bread in the United States, as much as ,35% of the daily thiamin requirement is now supplied r these foods.
Rice enrichment has been practiced for years in some fthe rice-eating countries. The Rice Research Institute in le Philippines has worked on the development of im,roved strains of rice and also on methods of enrichment. ,fuch of the rice used injapan is enriched. Dry yeast and wheat germ are the richest natural :ources of thiamin, but they are eaten only in relatively ;mall amounts. Except for pork, which is outstanding, muscle meats contain less than the organs, such as liver, heart, and kidney. Frui ts in general are poor sources of this vitamin.
