Fruit and Vegetable Consumption and Body Mass Index: A Quantile Regression Approach.
ABSTRACT Empirical evidence on the relationship between consumption of fruits and vegetables and body weight is inconclusive. Previous studies mostly use linear regression methods to study the correlates of the conditional mean of body mass index (BMI). This approach may be less informative if the association between fruit and vegetable consumption and BMI significantly varies across the BMI distribution.
The association between fruit and vegetable consumption and the BMI is examined using quantile regression.
A nationally representative sample of 11,818 individuals from the Canadian Community Health Survey (2004) is used. A quantile regression model is estimated to account for the potential heterogeneous association between fruit and vegetable intake and BMI at different points of the conditional BMI distribution. The analyses are stratified by gender.
The multivariate analyses reveal that the association between fruit and vegetable intake and BMI is negative and statistically significant for both males and females; however, this association varies across the conditional quantiles of the BMI distribution. In particular, the estimates are larger for individuals at the higher quantiles of the distribution. The ordinary least squares (OLS) model overstates (understates) the association between FV intake and BMI at the lower (higher) half of the conditional BMI distribution.
Findings of the standard models that assume uniform response across different quantiles of BMI distribution may be misleading. The findings of this paper suggest that increasing the intake of fruits and vegetables may be an effective dietary strategy to control weight and mitigate the risk of obesity.
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ABSTRACT: In Canada, demand for multidisciplinary bariatric (obesity) care far outstrips capacity. Consequently, prolonged wait times exist and contribute to substantial health impairments.A supportive, educational intervention (with in-person and web-based versions) designed to enhance the self-management skills of patients wait-listed for multidisciplinary bariatric medical and surgical care has been variably implemented across Alberta, Canada. However, its effectiveness has not been evaluated. Our objectives were: 1. To determine if this program improves clinical and humanistic outcomes and is cost-effective compared to a control intervention; and 2. To compare the effectiveness and cost-effectiveness of in-person group-based versus web-based care. We hypothesize that both the web-based and in-person programs will reduce body weight and improve outcomes compared to the control group. Furthermore, we hypothesize that the in-person version will be more effective but more costly than the web-based version. This pragmatic, prospective controlled trial will enrol 660 wait-listed subjects (220 per study arm) from regional bariatric programs in Alberta and randomly assign them to: 1. an in-person, group-based intervention (9 modules delivered over 10 sessions); 2. a web-based intervention (13 modules); and 3. controls who will receive mailed literature. Subjects will have three months to review the content assigned to them (the intervention period) after which they will immediately enter the weight management clinic. Data will be collected at baseline and every 3 months for 9 months (study end), including: 1. Clinical [5% weight loss responders (primary outcome), absolute and % weight losses, changes in obesity-related comorbidities]; 2. Humanistic (health related quality of life, patient satisfaction, depression, and self-efficacy); and 3. Economic (incremental costs and utilities and cost per change in BMI assessed from the third party health care payor perspective) outcomes. Covariate-adjusted baseline-to-nine-month change-scores will be compared between groups for each outcome using linear regression for continuous outcomes and logistic regression for dichotomous ones. Our findings will determine whether this intervention is effective and cost-effective compared to controls and if online or in-person care delivery is preferred. This information will be useful for clinicians, health-service providers and policy makers and should be generalizable to similar publically-funded bariatric care programs. Trial Identifier: NCT01860131.BMC Health Services Research 08/2013; 13:321. DOI:10.1186/1472-6963-13-321 · 1.66 Impact Factor
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ABSTRACT: Zoning ordinances and land-use plans may influence the community food environment by determining placement and access to food outlets, which subsequently support or hinder residents' attempts to eat healthfully. The objective of this study was to examine associations between healthful food zoning scores as derived from information on local zoning ordinances, county demographics, and residents' access to fruit and vegetable outlets in rural northeastern North Carolina. From November 2012 through March 2013, county and municipality zoning ordinances were identified and double-coded by using the Bridging the Gap food code/policy audit form. A healthful food zoning score was derived by assigning points for the allowed use of fruit and vegetable outlets. Pearson coefficients were calculated to examine correlations between the healthful food zoning score, county demographics, and the number of fruit and vegetable outlets. In March and April 2013, qualitative interviews were conducted among county and municipal staff members knowledgeable about local zoning and planning to ascertain implementation and enforcement of zoning to support fruit and vegetable outlets. We found a strong positive correlation between healthful food zoning scores and the number of fruit and vegetable outlets in 13 northeastern North Carolina counties (r = 0.66, P = .01). Major themes in implementation and enforcement of zoning to support fruit and vegetable outlets included strict enforcement versus lack of enforcement of zoning regulations. Increasing the range of permitted uses in zoning districts to include fruit and vegetable outlets may increase access to healthful fruit and vegetable outlets in rural communities.Preventing chronic disease 12/2013; 10:E203. DOI:10.5888/pcd10.130196 · 1.96 Impact Factor