Dietary assessment methods are often plagued with inconsistent or inaccurate data. Self-reported intakes are particularly susceptible to error as research has shown that humans habitually report food intake inappropriately. Self-reported intakes have been used to create energy recommendations for populations. In order to assess energy intake, a novel 4 day multimedia dietary assessment method was developed utilizing a tape-recorder and camera in an attempt to more accurately quantify energy intake than traditional methods. The Recommended Nutrient Intakes for Canadians ( RNIC) provide population mean energy estimations. An objective was to determine whether the RNIC provides an accurate index of energy requirements. Current literature suggests that the RNIC is inadequate in some populations to meet energy needs when validated against methods such as doubly-labelled water (DLW). Total energy expenditure (TEE) and body composition were determined through the use of DLW in 76 women (49--93 years) over 13 days. The multimedia diet records did not reflect true intake in these subjects as demonstrated by a mean 24% underreporting rate when compared to TEE. Mean energy expenditure (MJ/day) as determined by doubly-labelled water was significantly higher (p < 0.01) in each stratified age range when compared to reported energy intake by multimedia diet records. The use of tabulated RNIC's underestimated true energy requirements by a mean of 29%. Food and Agriculture Organization/World Health Organization energy predictions closely estimated actual TEE in the study population. This research agrees with current literature questioning the validity of self-reported dietary intake data.

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The Food Habits of Canadians Survey, conducted in 1997--1998 examined food and nutrient intakes of non-institutionalized adults aged 18--65 years (n = 1543) randomly selected from across Canada using the multi-stage random sampling strategy. Dietary intake was assessed by 24-h recall and a repeat interview was conducted in a sub-sample (n = 446). The overall response rate was 26%. Males, younger age adults (18--34 years), single persons and those with lower education levels were underrepresented in the study sample thus limiting the generalizability of the study results. Examination of the characteristics of the selected areas (n = 63) by response rates, indicated that areas with a higher percentage below the low income cut-off level, higher percentage who moved residence in the past 5 years and higher percentage speaking non-official languages as the mother-tongue were associated with low response rates. Additionally, areas with lower percentage females were associated with low response rates indicating that depending on the community characteristics different approaches may be needed to enhance response rates. Within- to between-subject variance ratios for several nutrients were higher when adjusted for age, gender, education, season, smoking and size of family compared to the crude ratios (e.g. for energy 1.07 vs. 0.49 for males). As a result, more days would be needed to reliably estimate usual intake once the data are appropriately adjusted. Examination of the within- to between-subject variability ratios for nutrients by smoking status indicated that the diet of smokers was no more variable than that of non-smokers. However, smokers had higher intakes of total fat (p < 0.05) and saturated fat (p < 0.05) and lower intakes of folate (p < 0.05) and vitamin C (p < 0.05). Smokers also had lower intakes of fruit and vegetables compared to non-smokers (p < 0.05). Given these differences, diet may be a confounder in studies examining smoking

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Perfluorinated carboxylates (PFCAs), sulfonates (PFSs) and perfluoroalkylsulfonamides (PFOSAs) have been detected in whole blood and serum of non-occupationally exposed humans, yet sources of exposure have not been fully elucidated. The objectives of this study were to estimate dietary exposure to perfluorooctane sulfonate (PFOS), PFCAs (C7--C 11) and fluorotelomer unsaturated carboxylates (FTUCAs) for the general Canadian and Inuit populations prior to the phase-out of perfluorooctyl-sulfonyl production by 3M and voluntary reductions in PFOA emissions under the PFOA stewardship program. PFCs were measured in 65 archived composite food samples prepared for the 1998 Canadian Total Diet Study (TDS) and 68 archived traditional foods from Nunavut using a newly developed methanol extraction combined with a solid phase extraction clean up. Dietary exposure was estimated using food intake data available from studies carried out between 1997 and 1998 in southern Canada and Nunavut. / PFCs were detected in eight composite food samples from the Canadian TDS and in 61 traditional food samples. Elevated concentrations of PFCs were found in caribou liver (6.2+/-5.5 ng/g), ringed seal liver (7.7, 10.2 ng/g), polar bear meat (7.0 ng/g), beluga meat (7.0, 5.8 ng/g), luncheon meats (5.02 ng/g), cookies (2.7 ng/g), processed cheese (2.1 ng/g) and peppers (1.8 ng/g). Low levels of total PFCs (&lt;1.5 ng/g) were measured in 41 traditional foods including: meat (caribou, ptarmigan, snow goose, bearded seal, walrus, black duck), berries, and fish (lake trout, arctic char). PFCs were not detected in beverages, unprocessed meats, breads, cereals and fruits from the TDS composite samples analyzed. / The ranges of estimated daily exposure to PFCs were between 2 and 59 ng-person-1 and 210 to 610 ng-person-1 for average Canadians and Inuit in Nunavut respectively. There were no statistically significant differences in mean PFC exposure levels for different age and gender groups in the general Canadian population. Inuit men in the 41 to 60 year old age group had statistically significantly higher estimated daily exposure to PFCs (p&lt;0.05) than younger men and women from the same age group. This higher exposure was associated with the consumption of beluga muktuk, caribou liver and bearded seal intestine. / Traditional foods contributed a higher percentage to PFC exposure than market foods in all age and gender groups for the Inuit population. In general, caribou meat, arctic char meat and cookies contributed most to dietary exposure for Inuit, with caribou flesh contributing 43 to 75 percent to daily PFC dietary exposure. Dietary exposure for the general Canadian population was associated with the consumption of cakes and cookies, processed cheese, and regular cheese. / Levels of dietary exposure to PFCs estimated in these studies do not pose any significant health risk to either population based on current toxicological information.

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