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close this book Food Composition Data: A User's Perspective (1987)
close this folder International food composition data
close this folder Food data in Canada: the Canadian nutrient file
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View the document Introduction
View the document Methods
View the document Discussion
View the document References

Methods

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

Food code Year added Food description Nutrition Canada code Flag

Factor

Refuse
          1 2 3 (%)
012a012 81 Cheese, cottage, creamed 0647 1b *c 100ML SM curd 100ML LG curd 0

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

No. of foods Percentage Nutrient code Unit Nutrient name
3,060 99.8 0203 g Protein
3,026 98.7 0206 g Fibre, crude
146 4.8 0273 g Fibre, neutral detergent
767 25.0 0806 g Fibre, total dietary (calculated)a
1,672 54.5 0309 mg Zinc
172 5.6 0339 µg Vitamin Db

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

Group no. Item no. Nutrient code Mean Standard error No. of observations Flag
01 2012 0203 12.49 0.1592 69  
    0312 0.02     5a

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.