Among the important responsibilities of FAO is a periodic appraisal of the world food situation. The basic material for such appraisals includes "food balance sheets" for individual countries. The preparation of food balance sheets involves three steps: (1) the collection by governments of data on available food supplies; (2) calculation of the amounts of the various foods and food groups available on a per caput basis made by dividing the total supplies by the number of people in the population; (3) calculation, based on step 2, of the calories and certain nutrients available on a per caput basis. Up to the present the only nutrients or classes of nutrients considered in drawing up food balance sheets have been proteins and fats.
The main purpose of the present tables is to facilitate the last step in the process of drawing up food balance sheets and to introduce into it a greater degree of uniformity. When the preparation of food balance sheets was first undertaken, it became evident from a study, of existing food composition tables that none could be satisfactorily used to make valid and comparable estimates on a world-wide basis, because of differences in various countries and regions in the analytical methods employed for determining food composition and in procedures for computing calorie and nutrient , values. When foods grown and consumed in different regions were really similar, these differences in methods often created an appearance of dissimilarity, while actual differences between regions were sometimes masked. In particular, the use of two major systems for reporting carbohydrates and two or more procedures for computing calories, with various combinations of these, led to confusion. Other disparities in methodology also contributed to lack of comparability.
In February 1947, a Committee on Calorie Conversion Factors and Food - Composition Tables was convened by FAO. The report of this Committee, Energy-yielding Components of Food and Computation of Calorie Values, suggested certain principles which might be followed in preparing food composition tables for international use. The FAO Standing Advisory Committee on Nutrition recommended in September 1947 that FAO should undertake the task of producing such tables. In accordance with the Committee's recommendations, the tables have now been drawn up. The methodo-logical disparities referred to above have been reduced and the terms and units employed are substantially uniform. A preliminary set of tables compiled in 1948 was used by the FAO secretariat in preparing food balance sheets. The present set includes revisions and additions, corresponding, insofar as possible within the time limits, with the suggestions put forward by the Standing Advisory Committee on Nutrition in 1948.
The author of the tables is a worker who has had many years of experience in the field of food composition analysis and who has prepared widely used national food composition tables for the United States of America. A large amount of material was analyzed, compared, and evaluated in order to obtain the values assigned to the various foods. The help of members of the Nutrition Division and others with knowledge of the subject, persons representing many countries, was available in the task of preparation. Thus the tables are based on extensive experience. It is certain that national food composition tables based on large numbers of analyses of foods locally consumed, and drawn up by sound methods, will give a more accurate picture of food composition in the country concerned than any set of internationally prepared tables. In the majority of countries, however, such tables do not exist at present. In their absence the use of the present tables as a practical tool for the purposes described above appears to be Justified and will develop accuracy and comparability in assessing the nutritive value of food supplies.
A handbook indicating the methods which member governments may follow in carrying out the first two steps in the process of preparing food balance sheets has already been issued. The present tables, which cover step 3, are therefore a companion work to the Handbook for the Preparation of Food Balance Sheets.
W. R. AYKROYD
Director, Nutrition Division