The accuracy of portion size estimation using food images and textual descriptions of portion sizes: an evaluation study.

BACKGROUND: Inaccurate self-report of portion sizes is a major cause of measurement error in dietary assessment. To reduce this error, different portion size estimation aids (PSEAs) have been developed, including food images (image based, IB-PSE) and textual descriptions of portion sizes (text-based, TB-PSE). We assessed the accuracy of portion size estimation by IB-PSE and TB-PSE. METHODS: True intake of one lunch was ascertained in forty participants. Self-reported portion sizes were assessed after 2 and 24 hours by means of TB-PSE and IB-PSE, in random order. Wilcoxon's tests were used to compare mean true intakes to reported intakes. Moreover, proportions of reported portion sizes within 10% and 25% of true intake were assessed. An adapted Bland-Altman approach was used to assess agreement between true and reported portion sizes. Analyses were conducted for all foods and drinks combined and for predetermined food types. RESULTS: No significant differences were observed between reported portion sizes at 2 and 24 hours after lunch. Combining median relative errors of all foods items resulted in an overall 0% error rate for TB-PSE and 6% error rate for IB-PSE. Comparing reported portion sizes within 10% (31% vs. 13%) and 25% (50% vs. 35%) of the true intake showed a better performance for TB-PSE compared to IP-PSE, respectively. Bland-Altman plots indicated a higher agreement between reported and true intake for TB-PSE compared to IB-PSE. CONCLUSIONS: Although the use of TB-PSE still results in measurement error, our results suggest a more accurate dietary intake assessment with TB-PSE than IB-PSE.

Dietary patterns with combined and site-specific cancer incidence in Alberta's Tomorrow Project cohort.

BACKGROUND/OBJECTIVES: Poor diet quality has been associated with an increased risk of cancer. Here, we examine the association between dietary patterns derived with two methods, and combined and site-specific cancer incidence in Canada. SUBJECTS/METHODS: Dietary data were obtained from participants enrolled in Alberta's Tomorrow Project, a prospective cohort study, between 2000 and 2008. Principle component analysis (PCA) and reduced rank regression (RRR) were used to derive dietary patterns, and data linkage with the Alberta Cancer Registry was used for incident cancer cases. Cox proportional hazard regressions were used to estimate multivariable-adjusted models for the association between each dietary pattern score with combined and site-specific cancer incidence. RESULTS: PCA revealed three dietary patterns ("western", "prudent", and "sugar, fruits, and dairy") and RRR resulted in four patterns ("dietary fiber", "vitamin D", "fructose", and "discretionary fat"). Five cancer sites were included in our site-specific analysis: lung, colon, breast, prostate, and endometrial cancers. The most protective dietary patterns for combined cancer sites were the "Prudent" pattern (HR = 0.82, CI = 0.73-0.92) and the "Dietary fiber" pattern (HR = 0.82, CI = 0.69-0.97). The "Fructose" pattern was associated with increased risk of combined cancers (HR = 1.14, CI = 1.02-1.27). Three dietary patterns were protective against colon cancer ("Prudent", "Dietary fiber", and "Discretionary fats"), and other risk reductions were seen for the "sugar, fruit, and dairy" pattern (lung cancer), and the "Dietary fiber" pattern (prostate cancer). CONCLUSIONS: These results support cancer prevention strategies for a diet high in vegetables, fruits, fish, and whole grains. Further studies should explore the possible association between discretionary fats and colon cancer.

The effects of shift work and sleep duration on cancer incidence in Alberta`s Tomorrow Project cohort.

INTRODUCTION: We investigated the main effects of shift work and sleep duration on cancer incidence, and effect modification of the shift work-cancer incidence association by sleep duration. METHODS: Shift work and sleep duration were assessed among 21,804 participants from Alberta`s Tomorrow Project. Incident cases of breast, prostate, colorectal and lung cancers were identified through registry linkage. RESULTS: Having worked ≥6 years of rotating shift work (HR = 1.59, 95 % CI = 1.07, 2.37; P = 0.02) and having ever worked night shifts were associated with an increased risk of lung cancer (HR=1.71, 95 % CI=1.18, 2.47; P = 0.01), whereas having ever worked night shifts was associated with a reduced risk of prostate cancer in the latency-adjusted model only (HR=0.70, 95 % CI=0.51, 0.98; P = 0.04). No associations were found between shift work or sleep duration on the risks of breast and colorectal cancers. Some evidence of effect modification by sleep duration for the rotating shift work-lung cancer incidence association was noted (P = 0.06), with stratified analyses revealing borderline increased risk of lung cancer in participants with ≥6 years of rotating shift work and <7 h of sleep/day (HR=2.27, 95 % CI=0.95, 5.41; P = 0.07), and an increased risk of lung cancer in participants with 0.1-5.9 years of rotating shift work and >9 h of sleep/day (HR=2.99, 95 % CI=1.12, 7.97; P = 0.03). No additional evidence of effect modification by sleep duration for shift work and cancer incidence was noted. DISCUSSION: A consistent association between shift work employment and lung cancer risk was noted in this Canadian sample. Furthermore, some evidence of effect modification of the rotating shift work-lung cancer risk association by sleep duration was noted.