Linking foodscapes and dietary behaviours : conceptual insights and empirical explorations in Canadian urban areas

La manière dont notre environnement influence le lieu et la nature de nos achats alimentaires n’est pas bien comprise. Un accès facilité ou limité aux commerces d’alimentation dits « sains » et « non-sains » a été considéré comme central dans la relation entre environnement et comportements alimentaires. De fait, la recherche a surtout tenté d’établir un lien entre, d’une part, facilité d’accès aux commerces « sains » et comportement sains, et, d’autre part, « déserts alimentaires » ‒ ces environnements socialement défavorisés offrant un accès limité aux sources d’alimentation saine ‒ et comportements non sains. Les écrits en santé publique manquent cependant de perspective sur les facteurs influençant le lieu et la nature des achats alimentaires dans les situations où les options qui s’offrent aux individus sont multiples, saines et moins saines. Pourtant, dans les villes occidentales caractérisées par une densité de commerces élevée et une mobilité individuelle facilitée, la réunion des conditions d’accès aux commerces d’alimentation « sains » comme moins « sains » est probablement situation courante. Partant de ce constat, cette thèse explore le lien entre environnements et comportements alimentaires dans plusieurs grandes villes canadiennes. En premier lieu, un cadre conceptuel est proposé, qui décrit les multiples facteurs influençant le lieu et la nature des achats alimentaires. Partant du postulat couramment adopté selon lequel les individus cherchent à tirer un maximum de bénéfices de leur environnement, ce cadre souligne l’importance de considérer les caractéristiques des commerces d’alimentation « sains » et « non sains » (ex. localisation, prix) en relation avec les préférences, moyens et contraintes des individus. L’attention est cependant attirée sur la capacité limitée des individus à opérer des choix pleinement informés. En effet, la réalisation de ces choix s’opère parfois sans grande conscience, en réaction à certains stimuli environnementaux. Sont notamment discutées les situations dans lesquelles le caractère approprié d’un comportement alimentaire est implicitement suggéré par l’environnement. Il est proposé que les densités relatives de commerces alimentaires « sains » et « non-sains » dans l’environnement auquel les individus sont exposés reflèteraient la relative popularité de ces lieux d’achat, et suggèreraient quels types de commerce il est « approprié » d’utiliser. Pour tester la plausibilité d’une telle proposition, cette thèse explore dans quelle mesure le pourcentage de commerces « sains » dans l’environnement des résidents adultes de cinq grands pôles urbains au Canada est associé à leur consommation de fruits et légumes. Les recherches présentées dans cette thèse portent à la fois sur les environnements autour du lieu de résidence (environnement résidentiel) et autour des divers lieux fréquentés par ces individus (environnement non résidentiel). Sont également testées d’éventuelles différences homme-femme dans ces associations, des différences de genre ayant été soulignées dans les recherches s’intéressant à la relation entre environnements et comportements alimentaires. Conformément aux hypothèses émises, une association positive entre pourcentage de magasins « sains » dans l’environnement résidentiel et consommation de fruits et légumes est observée. Une relation plus forte chez les hommes que chez les femmes est également relevée. En revanche, la consommation de fruits et légumes n’est pas reliée au pourcentage de magasins « sains » dans l’environnement non résidentiel et ce, ni chez les hommes ni chez les femmes. En proposant un cadre conceptuel innovant, que viennent en partie conforter les résultats de notre recherche empirique, cette thèse contribue à la construction d’une meilleure compréhension des influences environnementales sur les comportements de santé.In westernised cities where food is mostly acquired in the retail and catering environment, there may be a link between the foodscape - i.e. the multiplicity of publicly available sites where food is displayed for purchase - and where and what we buy and eat. Yet, how the foodscape shapes dietary behaviours remains unclear. Ease and difficulty of access to “healthy” and “unhealthy” food sources has been recognised as central in the foodscape-diet relationship. As a result, empirical research has mostly investigated the associations between ease of access to healthy outlets and healthy behaviours, on one hand, and “food deserts” – deprived environments lacking access to healthy food outlets – and unhealthy behaviours, on the other hand. However, public health literature lacks perspective on the factors that influence where to purchase and what to eat in situations of multiple – healthy and less healthy – choices. Yet, in industrialised urban contexts characterised by pervasive food retail and facilitated individual mobility, conditions for accessing both healthy and less-healthy food sources are probably commonly met. Based on these observations, this thesis intents to explore the relationship between foodscapes and dietary behaviours in Canadian urban areas. Firstly, conceptual insights on the multiple factors shaping where to shop and what to eat are provided. Drawing from the commonly held assumption that individuals operate choices that tend to maximize their self-interests, the proposal highlights the importance of considering food outlets’ characteristics (ex. localisation, price, services offered) relatively to individuals’ preferences, constraints and means. However attention is brought on individuals’ limited ability to operate fully-informed choices. Food choices sometimes unfold without much deliberation, as a result of the mere perception of cues in the environment. Especially discussed are the situations where exposure to cues signaling appropriateness of a dietary behaviour provokes the adoption of similar behaviours. It is then suggested that the relative densities of healthy and unhealthy outlets individuals get exposed to may drive a normative message about the relative popularity of these places, and suggest which places are “appropriate” to use. This thesis then investigates the extent to which relative exposures to healthy and unhealthy food outlets are associated to dietary behaviours. Drawing on multiple secondary datasets pertaining to adult residents of five large Canadian cities, associations between the percentage of healthy outlets in the residential neighborhood and fruit and vegetables intake are examined. As literature highlighted gender differences in the foodscape-diet relationship, whether these associations are different for men and women are further investigated. Finally, these investigations extend to the non-residential environment. Consistent with our expectations, our research provides evidence of a positive association between the percentage of healthy outlets around home and fruit and vegetable intake. Stronger associations for men than for women were further observed. However, fruit and vegetable intake was not related to the non-residential foodscape, neither for men nor for women. By providing conceptual justification for, and empirical evidence of, a link between dietary behaviours and relative exposures to healthy and unhealthy outlets, this thesis contributes to better understand how the foodscape shapes dietary behaviours

Geographic Variability in the Association between Socioeconomic Status and BMI in the USA and Canada

Objective: Reported associations between socioeconomic status (SES) and obesity are inconsistent depending on gender and geographic location. Globally, these inconsistent observations may hide a variation in the contextual effect on individuals' risk of obesity for subgroups of the population. This study explored the regional variability in the association between SES and BMI in the USA and in Canada, and describes the geographical variance patterns by SES category. Methods: The 2009–2010 samples of the Behavioral Risk Factor Surveillance System (BRFSS) and the Canadian Community Health Survey (CCHS) were used for this comparison study. Three-level random intercept and differential variance multilevel models were built separately for women and men to assess region-specific BMI by SES category and their variance bounds. Results: Associations between individual SES and BMI differed importantly by gender and countries. At the regional-level, the mean BMI variation was significantly different between SES categories in the USA, but not in Canada. In the USA, whereas the county-specific mean BMI of higher SES individuals remained close to the mean, its variation grown as SES decreased. At the county level, variation of mean BMI around the regional mean was 5 kg/m2 in the high SES group, and reached 8.8 kg/m2 in the low SES group. Conclusions: This study underlines how BMI varies by country, region, gender and SES. Lower socioeconomic groups within some regions show a much higher variation in BMI than in other regions. Above the BMI regional mean, important variation patterns of BMI by SES and place of residence were found in the USA. No such pattern was found in Canada. This study suggests that a change in the mean does not necessarily reflect the change in the variance. Analyzing the variance by SES may be a good way to detect subtle influences of social forces underlying social inequalities

The Local Food Environment and Fruit and Vegetable Intake: A Geographically Weighted Regression Approach in the ORiEL Study.

Studies that explore associations between the local food environment and diet routinely use global regression models, which assume that relationships are invariant across space, yet such stationarity assumptions have been little tested. We used global and geographically weighted regression models to explore associations between the residential food environment and fruit and vegetable intake. Analyses were performed in 4 boroughs of London, United Kingdom, using data collected between April 2012 and July 2012 from 969 adults in the Olympic Regeneration in East London Study. Exposures were assessed both as absolute densities of healthy and unhealthy outlets, taken separately, and as a relative measure (proportion of total outlets classified as healthy). Overall, local models performed better than global models (lower Akaike information criterion). Locally estimated coefficients varied across space, regardless of the type of exposure measure, although changes of sign were observed only when absolute measures were used. Despite findings from global models showing significant associations between the relative measure and fruit and vegetable intake (β = 0.022; P < 0.01) only, geographically weighted regression models using absolute measures outperformed models using relative measures. This study suggests that greater attention should be given to nonstationary relationships between the food environment and diet. It further challenges the idea that a single measure of exposure, whether relative or absolute, can reflect the many ways the food environment may shape health behaviors

Association between Activity Space Exposure to Food Establishments and Individual Risk of Overweight

Objective: Environmental exposure to food sources may underpin area level differences in individual risk for overweight. Place of residence is generally used to assess neighbourhood exposure. Yet, because people are mobile, multiple exposures should be accounted for to assess the relation between food environments and overweight. Unfortunately, mobility data is often missing from health surveys. We hereby test the feasibility of linking travel survey data with food listings to derive food store exposure predictors of overweight among health survey participants. Methods: Food environment exposure measures accounting for non-residential activity places (activity spaces) were computed and modelled in Montreal and Quebec City, Canada, using travel surveys and food store listings. Models were then used to predict activity space food exposures for 5,578 participants of the Canadian Community Health Survey. These food exposure estimates, accounting for daily mobility, were used to model self-reported overweight in a multilevel framework. Median Odd Ratios were used to assess the proportion of between-neighborhood variance explained by such food exposure predictors. Results: Estimates of food environment exposure accounting for both residential and non-residential destinations were significantly and more strongly associated with overweight than residential-only measures of exposure for men. For women, residential exposures were more strongly associated with overweight than non-residential exposures. In Montreal, adjusted models showed men in the highest quartile of exposure to food stores were at lesser risk of being overweight considering exposure to restaurants (OR = 0.36 [0.21–0.62]), fast food outlets (0.48 [0.30–0.79]), or corner stores (0.52 [0.35–0.78]). Conversely, men experiencing the highest proportion of restaurants being fast-food outlets were at higher risk of being overweight (2.07 [1.25–3.42]). Women experiencing higher residential exposures were at lower risk of overweight. Conclusion: Using residential neighbourhood food exposure measures may underestimate true exposure and observed associations. Using mobility data offers potential for deriving activity space exposure estimates in epidemiological models

Associations between home and school neighbourhood food environments and adolescents' fast-food and sugar-sweetened beverage intakes: findings from the Olympic Regeneration in East London (ORiEL) Study.

OBJECTIVE: To examine associations between availability of fast-food restaurants and convenience stores in the home and school neighbourhoods, considered separately and together, and adolescents' fast-food and sugar-sweetened beverage (SSB) intakes. DESIGN: Cross-sectional observational study. SETTING: East London, UK. SUBJECTS: Adolescents (n 3089; aged 13-15 years) from the Olympic Regeneration in East London (ORiEL) Study self-reported their weekly frequency of fast-food and SSB consumption. We used food business addresses collected from local authority registers to derive absolute (counts) and relative (proportions) exposure measures to fast-food restaurants and convenience stores within 800 m from home, school, and home and school combined. Associations between absolute and relative measures of the food environment and fast-food and SSB intakes were assessed using Poisson regression models with robust standard errors. RESULTS: Absolute exposure to fast-food restaurants or convenience stores in the home, school, or combined home and school neighbourhoods was not associated with any of the outcomes. High SSB intake was associated with relative exposure to convenience stores in the residential neighbourhood (risk ratio=1·45; 95 % CI 1·08, 1·96) and in the home and school neighbourhoods combined (risk ratio=1·69; 95 % CI 1·11, 2·57). CONCLUSIONS: We found no evidence of an association between absolute exposure to fast-food restaurants and convenience stores around home and school and adolescents' fast-food and SSB intakes. Relative exposure, which measures the local diversity of the neighbourhood food environment, was positively associated with SSB intake. Relative measures of the food environment may better capture the environmental risks for poor diet than absolute measures

Media representations of opposition to the 'junk food advertising ban' on the Transport for London (TfL) network: A thematic content analysis of UK news and trade press.

BackgroundAdvertising of less healthy foods and drinks is hypothesised to be associated with obesity in adults and children. In February 2019, Transport for London implemented restrictions on advertisements for foods and beverages high in fat, salt or sugar across its network as part of a city-wide strategy to tackle childhood obesity. The policy was extensively debated in the press. This paper identifies arguments for and against the restrictions. Focusing on arguments against the restrictions, it then goes on to deconstruct the discursive strategies underpinning them.MethodsA qualitative thematic content analysis of media coverage of the restrictions (the 'ban') in UK newspapers and trade press was followed by a document analysis of arguments against the ban. A search period of March 1, 2018 to May 31, 2019 covered: (i) the launch of the public consultation on the ban in May 2018; (ii) the announcement of the ban in November 2018; and (iii) its implementation in February 2019. A systematic search of printed and online publications in English distributed in the UK or published on UK-specific websites identified 152 articles.ResultsArguments in favour of the ban focused on inequalities and childhood obesity. Arguments against the ban centred on two claims: that childhood obesity was not the 'right' priority; and that an advertising ban was not an effective way to address childhood obesity. These claims were justified via three discursive approaches: (i) claiming more 'important' priorities for action; (ii) disputing the science behind the ban; (iii) emphasising potential financial costs of the ban.ConclusionThe discursive tactics used in media sources to argue against the ban draw on frames widely used by unhealthy commodities industries in response to structural public health interventions. Our analyses highlight the need for interventions to be framed in ways that can pre-emptively counter common criticisms

Longitudinal impact of changes in the residential built environment on physical activity: findings from the ENABLE London cohort study.

BACKGROUND: Previous research has reported associations between features of the residential built environment and physical activity but these studies have mainly been cross-sectional, limiting inference. This paper examines whether changes in a range of residential built environment features are associated with changes in measures of physical activity in adults. It also explores whether observed effects are moderated by socio-economic status. METHODS: Data from the Examining Neighbourhood Activity in Built Living Environments in London (ENABLE London) study were used. A cohort of 1278 adults seeking to move into social, intermediate, and market-rent East Village accommodation was recruited in 2013-2015, and followed up after 2 years. Accelerometer-derived steps (primary outcome), and GIS-derived measures of residential walkability, park proximity and public transport accessibility were obtained both at baseline and follow-up. Daily steps at follow-up were regressed on daily steps at baseline, change in built environment exposures and confounding variables using multilevel linear regression to assess if changes in neighbourhood walkability, park proximity and public transport accessibility were associated with changes in daily steps. We also explored whether observed effects were moderated by housing tenure as a marker of socio-economic status. RESULTS: Between baseline and follow-up, participants experienced a 1.4 unit (95%CI 1.2,1.6) increase in neighbourhood walkability; a 270 m (95%CI 232,307) decrease in distance to their nearest park; and a 0.7 point (95% CI 0.6,0.9) increase in accessibility to public transport. A 1 s.d. increase in neighbourhood walkability was associated with an increase of 302 (95%CI 110,494) daily steps. A 1 s.d. increase in accessibility to public transport was not associated with any change in steps overall, but was associated with a decrease in daily steps amongst social housing seekers (- 295 steps (95%CI - 595, 3), and an increase in daily steps for market-rent housing seekers (410 95%CI -191, 1010) (P-value for effect modification = 0.03). CONCLUSION: Targeted changes in the residential built environment may result in increases in physical activity levels. However, the effect of improved accessibility to public transport may not be equitable, showing greater benefit to the more advantaged

Should we use absolute or relative measures when assessing foodscape exposure in relation to fruit and vegetable intake? Evidence from a wide-scale Canadian study.

OBJECTIVE: This paper explores which of absolute (i.e. densities of "healthy" and "unhealthy" food outlets taken separately) or relative (i.e. the percentage of "healthy" outlets) measures of foodscape exposure better predicts fruit and vegetable intake (FVI), and whether those associations are modified by gender and city in Canada. METHODS: Self-reported FVI from participants of four cycles (2007-2010) of the repeated cross-sectional Canadian Community Health Survey living in the five largest metropolitan areas of Canada (n=49,403) was analyzed. Absolute and relative measures of foodscape exposure were computed at participants' residential postal codes. Linear regression models, both in the whole sample and in gender- and city-stratified samples, were used to explore the associations between exposure measures and FVI. RESULTS: The percentage of healthy outlets was strongly associated with FVI among men both in Toronto/Montreal (β=0.012; P<0.001), and in Calgary/Ottawa/Vancouver (β=0.008; P<0.001), but not among women. Observed associations of absolute measures with FVI were either weak or faced multicollinearity issues. Overall, models with the relative measure showed the best fit. CONCLUSIONS: Relative measures should be more widely used when assessing foodscape influences on diet. The absence of a single effect of the foodscape on diet positions sub-group analysis as a promising avenue for research