From a public health standpoint the nutritional deficiency diseases are not a cause for undue alarm in Canada. Cases of this nature are comparatively rare, e.g. at the Hospital for Sick Children in Toronto in 1925 there were 154 cases of rickets. Ten years later, in 1935, there were only four. However, from dietary surveys made in Canada and the United States it is quite apparent that of the populations of both countries as many as one-third are receiving diets which are not in line with optimum health. The point stressed in these surveys was that the diets of the people of both countries are deficient in vitamin B1 or thiamin. Surveys in Canada show that the average daily intake ranges from less than 0.6 to 1.2 milligrams per day. This is to be contrasted to a recommended daily intake of 1.8 milligrams for men and 1.5 milligrams for women, approved by the Canadian Council on Nutrition in 1942. From the large numbers of assays which have been made of a wide variety of animal and vegetable tissues it is clear that thiamin is of nearly universal occurrence in quantities ranging from 0.1 to 2.0 micrograms per gram. In the wide variety of products in the plant world these amounts are exceeded only in seeds and yeast grown in rich media. The task of estimating the thiamin supplied by mixed diets requires accurate analysis of a large number of essential foods. Vegetables rank high in the dietaries of not only Canada but also other countries of the world. A knowledge of the amount of thiamin present in such home products is necessary in order that programs to alleviate the above mentioned lack of this factor may be initiated...