Methods

Data source
Analytical techniques

Data source

Most of the data in this analysis are from the 2004 Canadian Community Health Survey (CCHS) — Nutrition, which was designed to collect information about the dietary habits of Canadians (/concepts/hs-es/index-eng.htm).  The CCHS excludes members of the regular Canadian Forces and people living in the territories, on Indian reserves, in institutions, in some remote regions, and all residents (military and civilian) of Canadian Forces bases.  Detailed descriptions of the CCHS design, sample and interview procedures are available in a published report.¹

An initial 24-hour dietary recall was completed by 35,107 people; a subsample (10,786) completed a second recall 3 to 10 days later.  A five-step method was used to maximize recollection of food consumed the previous day:

• a quick list (respondents reported all items in whatever order they wished)

• questions about specific food categories and frequently forgotten foods

• questions about the time and type of meal

• questions seeking more detailed, precise descriptions of foods/beverages and quantities consumed

• a final review.

Respondents could report basic food items (for example, an apple) or a recipe (for example, lasagna).  To determine the individual food items that constitute recipes, standard recipes were used.  However, when respondents reported a recipe, interviewers probed in order to find out if the recipe contained non-standard ingredients.

The response rate for the first interview was 76.5%, and for the second, 72.8%.  Composition of the food in terms of macro- and micronutrients came from the Canadian Nutrient file 2001b Supplement² of Health Canada.

A total of 112 cases with invalid intake and 20 cases with null intake were excluded from this  analysis.  Pregnant women (175), women who were breastfeeding (91), and 4-year-old children who were being breastfed (3) were also excluded.

Published results from the 1970-1972 Nutrition Canada Survey were used to compare calorie and fat  intake three decades ago with the 2004 results.  The response rate for the 1970-1972 survey, which collected data for 10,994 respondents aged 5 or older, was 47%.

Top of Page

Analytical techniques

Data collected on the first interview day were used to estimate, by age and sex, average energy intake (calories) and average percentages of energy from fat, protein and carbohydrates.  To determine the calories derived from each of these three macronutrients, amounts in grams were multiplied by 9, 4 and 4, respectively.  Averages were defined as the average of the ratios for each individual.  Total energy intake includes calories from alcoholic beverages (7 calories per gram), but the percentage of calories from alcohol is not shown separately.

Usual intake of macronutrients was estimated using data from both interview days and the Software for Intake Distribution Estimation (SIDE) program^3,4  (see One-day versus usual intake).

The foods (basic food items, recipes, or ingredients) were categorized into four groups as defined in Canada’s Food Guide to Healthy Eating⁵ — vegetables etables and fruit, milk products, meat and alternatives, and grain products — and “other foods.”  There was no double-counting; for example, if a recipe was coded as “other foods,” the recipe, not the ingredients, was used, and vice versa.  As was done for macronutrients, descriptive statistics were used to estimate daily calories from each food group and the number of servings consumed per day.  The distribution of usual servings from each food group was estimated with the SIDE program.³

Quantities expressed in grams were transformed into servings for vegetables and fruit, milk products, and grain products, using the Canadian Nutrient File² provided by Health Canada.  Quantities for the meat and alternatives group were expressed in terms of cooked meat, with one serving containing 50 to 100 grams of meat.  Servings defined without a range (peanut butter, for example) were multiplied by a factor equal to 50 grams of cooked meat.

The percentage of energy from a particular food group was defined as total calories from that food group in a population, divided by the total calories consumed by that population.  The same method was used to calculate the percentage of fat coming from particular food groups.

The foods accounting for the most calories from “other foods” were derived using food item and recipe categories (Table 2).  Categories are specific to a food item or a recipe.  Some categories are similar for food items and recipes.  Therefore, salad dressings and fruit drinks include elements assigned as a food item or as a recipe.

To determine the foods accounting for the most fat consumed in a day, basic food items and recipes were considered (Table 4).  The categories “sweet baked goods,” “milk and milk-based beverages,” “chicken dishes” and “egg dishes” are from food and recipe categories.  However, “salads” include dressing only if it is part of the recipe, not if it is reported separately.  “Pasta dishes” do not include pasta reported separately, and “cheese dishes” do not include cheese reported separately.

The percentage of calories or fat is defined as total calories or total fat from a category, divided by total calories or total fat for all categories (Table 2 and Table 4).

The percentage of the population who had a specific meal (breakfast, lunch, dinner) or ate between meals (snacks) was defined as the number of people who did so the first day of the interview divided by the total population reporting on the first day.  This percentage is a snapshot of a given day; it does not show the frequency with which individuals typically have a particular meal or consume snacks.  Similarly, the percentage of calories from a specific meal (breakfast, lunch, dinner, snacks) was also defined as the number of calories that the population consumed from that meal, divided by the total number of calories the population consumed in a day.

The same method was used to determine locations where food was prepared (home, fast-food outlet, other). 

The bootstrap method, which takes into account the complex survey design,^6‑8 was used to estimate standard errors, coefficients of variation and confidence intervals. The significance level was set at p < 0.05.