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Food data in Canada: the Canadian nutrient file

Introduction
Methods
Discussion
References

PAMELA C. VERDIER

Bureau of Nutritional Sciences, Food Directorate, Health Protection Branch,
Health and Welfare Canada, Ottawa, Ontario, Canada

Introduction

The first Table of Food Values Recommended for Canadian Use was produced by the Department of Pensions and National Health in 1944 [6]. The second edition [3] contained the statements, "There is scarcely one single food for which complete analyses made in a Canadian laboratory are available" and "Where Canadian values were available in sufficient range they have been used." This edition used data from USDA Agriculture Handbook No. 8, 1950 [8]. In the late 1960s, the information was revised and reformated into a computerized version for calculating the 24 hour recall food consumption portion of the Nutrition Canada Survey, 19711972 [1]. The source of the data was, in most cases, USDA Handbook No. 8, 1963 [8]. "Canadian only" foods were entered, examples being all baked goods sold in the province of Newfoundland; these are made with "Newfoundland flour," a calcium-enriched product. Cooking-yield factors were applied to raw foods where cooked values were not available, some nutrient analyses were performed and appropriate levels of fortification of various foods changed to meet Canada's food and drug regulations. After the survey, this data base was made available to persons able to use it, and various other nutrient values (such as zinc and copper in a limited number of foods) were added over the years to meet the needs of the Bureau of Nutritional Sciences. By 1978, no more foods or nutrients could be added and it was decided to reformat the entire tape into a more flexible and accessible form, to be called the Canadian Nutrient File (CNF).

Methods

In setting up the new file, a three-subfile layout was designed to facilitate easy access and manipulation of the data. The three subfiles were: the Food Name Subfile, the Nutrient Name Subfile, and the Nutrient Amount Subfile. USDA was then in the process of issuing updated Handbook No. 8 food groups, and so, in reformating the data for the new file, a coding system incorporating the new USDA codes and containing an extra digit for Canadian use was developed.

Table 1. Example of Food Name Subfile

a. Food with nutrients added.
b. Improved data added after 1981.
c. Star indicates that 100ML edible portion conversion factor is available for this food (in this case factor t is fo'r a "not further specified" food description).

The Food Name Subfile (table 1), in English and French, includes the food name, the new food code, the old Nutrition Canada Survey food code based on Handbook No. 8, 1963 (the year the food was added to the data base) [1], an editorial flag, and four conversion factors. The extra digit was added to the new USDA food codes to indicate whether the food was the same as in Handbook No. 8 (in which case the number was zero) or what modifications were made (foods with some nutrient values entered for Canadian levels of fortification, values analysed in Canada, calculated values, etc.). "Canadian only" foods were coded similarly and incorporate within the code the closest USDA food description. The Nutrition Canada Survey food codes, if applicable, were included for the convenience of those persons used to the Nutrition Canada Survey conversion factors. The year the food was added to the base is included to facilitate retrospective studies. When an update is needed because of a change in formulation of a food, the code is left intact and a new food record is created with the appropriate year. The editorial flag indicates that improved data have been added although the food itself has not changed. Portion sizes other than the "100-gram edible portions" are available by multiplying the 100-gram portion values by four factors. Multiplying by factor I gives the edible portion in l00 ml (for volumetric measurements); factors 2 and 3 have 15-digit descriptors for common portion sizes, such as: 1 large egg, lOOml pureed, slice 10 x 10 x 0.2, etc. (all dimensions are in centimetres and all factors have been recalculated for metric volumes); and factor 4 gives 1 kg as purchased.

The Nutrient Name Subfile (table 2), in English and French, contains a description of the nutrient, the three-digit USDA nutrient code, and the measure associated with each nutrient [7]. Also provided with the tape is a listing of the number and percentage of foods in the file that have values for each nutrient. This assists the user in deciding whether a meaningful survey of a specific nutrient can be undertaken.

The Nutrient Amount Subfile (table 3) identifies the food by the new Canadian food code and gives the nutrient codes with all available nutrient data expressed per 100-gram edible portion. A single-digit flag is added to each nutrient value to show how the item differs from the USDA value because of added, calculated, substituted, or imputed nutrients. When there is no flag, no change has been made.

Table 2. Nutrient Name Subfile examples

a. Values calculated from Paul and Southgate [7] by the Ludwig cancer Institute, Toronto Ontario.
b. vitamin D in µg to conform with Canadian recommendations.

Table 3. Nutrient Amount Subfile examples

a. 5 = nutrient imputed from a similar food.

Canada still has little original data on Canadian foods, although some Canadian research data have been incorporated into the Handbook No. 8 series (both 1963 and present). Folic acid values in many foods and pantothenic acid in cereals are examples. As each new food-group book is issued by USDA, the data are examined for relevance to the Canadian situation by consultation with experts from Agriculture Canada, university departments, and the appropriate food manufacturers and marketing boards. Canadian research values are entered, where available, and levels of fortification are changed to meet Canadian food regulations. Breakfast foods in Canada are not as highly fortified as in the United States, and, consequently, Canadian manufacturers' values, supplemented by Canadian research data, are used for this food group. Certain Handbook No. 8 values are, nevertheless, added when the determinations are not available from a Canadian source and the food descriptions are the same as in the handbook (e.g. copper and magnesium for Kellogg's Corn Flakes). Some changes are made to meet the Canadian food situation: canola (rape-seed) oil is used in all commercial salad dressings and mayonnaises in Canada, and Canadian analytical values for fatty acids are therefore entered for these products. Some foods with completely calculated nutrient values are included: 2 per cent evaporated milk (calculated from USDA Handbook No. 8 values for evaporated milk, whole, and skim). Imputations of nutrients from a similar food (such as zinc and copper) are kept to a minimum and no attempt is made to impute "missing values" for foods that have incomplete data. All Canadian entries, substitutions, calculations, or imputations are flagged and readily identifiable. Food names are changed to reflect Canadian usage: "Cheese, processed, American" becomes "Cheese, processed, Cheddar." "Canadian only" foods are added where data are available and foods not on the Canadian market (such as unenriched flour and flour products) are deleted.

The new format includes metric portions only. As Canada is a bilingual country, the users' manual accompanying the nine-track, 1600 BPI tape is in English and French, the two official languages. Instructions are also provided for the computer programmer and include a printout of the Food Name and Nutrient Name Subfiles. The tape, written in COBOL, may be accessed by any computer language but no software program is provided. The file is created on an Andahl 470-V8 computer and the tapes, which are updated annually from the USDA data tapes, are for sale. The first tape was issued in December 1981.

In the early 1950s, a table of nutrient values for 185 foods was prepared as part of a nutrition education booklet, Healthful Eating [2], which was written for teachers, nurses, and the general public. Because of the large demand for this publication, an expanded separate leaflet called Nutrient Value of Some Common Foods [4] was issued. This has continued to expand and is available, free, in both official languages. It now provides values in customary household measures for moisture, energy, and 17 nutrients. A bilingual tape, containing values for the 608 foods and the nutrients included in the present publication, was prepared for persons wanting a smaller, more manageable data base. It can be sorted either alphabetically or by food group and is based on 100 gram edible portions, with one factor providing the common household measure. It is also to be updated annually.

Discussion

The reformated file was designed to provide all reliable nutrient data available for the described foods and to include features that would facilitate its use. It was developed for Health and Welfare Canada to calculate nutrient intakes in food consumption surveys and to analyse menus for food-fortification or food-substitution studies. Agriculture Canada also had a need for such data and it was hoped that it would provide a national file on which all Canadian studies could be based. User comments were solicited from the beginning and changes have been made in the format to facilitate use. A major change was from seven conversion factors, described in the user's manual accompanying the tape (in the first two editions), to the four factors described on the present tape.

A National CNF User's Workshop was organized in June 1984 in Toronto, Ontario, to promote the general use of the file and share experiences in using it. Development of software programs requires the skills of both a nutritionist and a computer programmer. Agriculture Canada, with nutritionists, statisticians, and programmers, acquired the tape and has developed a very extensive programme: their nutrient-analysis computer program (AGNAP) has both nutritional and statistical input. Most of the nutritional data in AGNAP come from the CNF, but there is also a cookiny-yield file for "in-house" research information. Six types of reports can be produced: recipe/menu analysis, food ranking by amount of specific nutrient, cost of food per unit of nutrient, apparent nutrient intakes, nutritive value of food purchased, and nutritious foodbasket data manipulations. Statistics Canada provides data for four other reference files: a population file, providing estimates of demographic groups within the Canadian population; a food disappearance data file, outlining the apparent per capita food consumption in Canada between 1960 and 1983 (updated annually); a family food expenditure data file, including the quantities of food purchased by various socioeconomic groups within Canada (derived from a continuing market basket survey); and a retail food prices file, based on Statistics Canada's consumer price index. From these are derived three programs: the Apparent Nutrient Intakes program, the Nutritive Value of Food Purchased program, and the Agriculture Canada Nutritious Food Basket development program. At the other end of the scale, a nutritionist in a rural community, with specific needs for the evaluation of nutrient intakes in hospital food services, nursing homes, and boardinghouses, wrote a program on a microcomputer including nutrient assessment of individuals and menu planning, and now has extended use with a modem connection to a local university to access the entire CNF.

Several users have had special programs written for such projects as a regional hospital foodservices group that supplies prepared frozen foods daily to seven hospitals with a completely computerized program for food purchase, quality control, menu planning, ingredient delivery, assembly, cooking, freezing, and storage prior to delivery. Attached to these programs are nutrient compositions of all foods as delivered. A food-service organization, providing bulk foods to boarding-houses and nursing homes, includes computerized recipes, menus and probable nutrient intakes.

Most users buy a software program, including all or part of the CNF. Services are also available for the submission of data to a university computer centre for computation. As the capacity of microcomputers expands, more and more programs are able to store and access the entire file. Programs are becoming more sophisticated and various user needs are being met. Canadian programmers, using their experience in developing packages for the CNF, are working on software systems for third-world countries.

A further extension of the CNF is in progress with the development of a data file for use in dietetics in Canadian hospitals. Louise Bell, a nutritionist at the Hospital for Sick Children in Toronto, is modifying the file to include imputations of missing values, standard foods, brandname foods including infant formula and enteral feedings, special dietetic products, and vitamin and mineral supplements, with unused foods being deleted. The first issue will have complete data for all foods covering 24 nutrients.

Interest is developing in identifying areas where Canadian data are needed for differences in the foods, and in defining research programmes to fill these gaps. Contracts have been made out by Agriculture Canada for meat [5] and other analyses, and an ongoing assessment of the Canadian food supply is being conducted by Health and Welfare Canada, in conjunction with the Total Diet Study, regarding specific nutrients where differences from the US data might be expected or where data are now missing (e.g. fat levels in meats and neutral detergent fibre in many foods). The Field Operations Directorate of Health and Welfare Canada already samples and analyses certain selected foods and nutrients each year and provides data that are useful in checking the applicability of the USDA data. Over the years, such research will help to increase the proportion of Canadian data in the CNF.

Data are missing for northern animal, fish, and plant foods. Recommendations to resume consumption of available "land foods" in the north must be supported by data on nutrient content. As only a small part of the population consumes such foods, little research interest exists, and an exchange of data with other northern countries is being sought.

The CNF format is compatible with that of USDA and will form part of the NOAFOODS regional network.

References

1. Department of National Health and Welfare, Food Consumption Patterns Report (Bureau of Nutritional Sciences, Health Protection Branch, Ottawa, 1976).

2. Department of National Health and Welfare, Healthful Eating (Nutrition Division, Ottawa, 1952).

3. Department of National Health and We]fare, Table of Food Values Recommended for Use in Canada (Nutrition Division, Ottawa 1951).

4. Health and Welfare Canada, Nutrient; Value of Some Common Foods (Health Services and Promotion Branch and Health Protection Branch, Ottawa, 1983).

5. S. D. M. Jones, "Chemical Composition of Selected Cooked Beef Steaks and Roasts," J. Can. Diet. Assoc., 46:40 44 (1985).

6. M. E. Macbeth and L. B. Pett, Table of Food Values Recommended for Canadian Use (Nutrition Services, Department of Pensions and National Health, Ottawa, 1944).

7. A. A. Paul and D.A.T. Southgate, McCance and Widdowson's: The Composition of Foods, 4th ed. (HMSO, London, 1978).

8. US Department of Agriculture, "Composition of Foods: Raw, Processed, Prepared," Agriculture Handbook No. 8 (Science and Education Administration, USDA, Washington, D.C., 1950, 1963).

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