Preprint · Jan 2020
Changes in the nutritional quality and environmental impact of diet: a longitudinal study before, during and one year after the 2020 COVID-19 lockdown in France
By Marty L, Nicklaus S
Background and rationale Between the 17th of March and the 10th of May 2020, most of the French population was self-isolated at home as part of the prevention measures against the COVID-19 pandemic. Going for grocery shopping in stores that remained open was allowed. However, this unusual situation is likely to have influenced the food consumption pattern of the French population. A large part of our behaviours are habits, i.e., automatic associations between specific context cues and responses, which have a history of repetition and reward. Habits form as people pursue goals by repeating the same responses in a given context and then become automatic and hard to change [1]. Food choice behaviours are particularly stable in adulthood [2]–[5] and because they are performed every day and usually in the same context they likely result from a habitual response. However, when people are undergoing changes in their environment, habits are vulnerable to change as people engage in a new non-automatic process of decision making [6]. Thus, we hypothesise that the unusual lockdown situation may have caused discontinuities in food habits and food choice motives. In a constructionist perspective, food choice motives are part of one’s personal food system that is shaped by life course events and various influences (e.g., cultural ideas, personal factors, etc.) and contribute to food choice decisions making, leading to food choice behaviours [7], [8]. It means that a change in food choice motives may lead to a change in food choice behaviours. The most important food choices criteria are taste, cost, nutrition and convenience with a large interindividual variability [9]. Moreover, recent surveys that were carried on in France during the lockdown have shown that French consumers declared being more attracted to local and organic food products during the lockdown [10], [11]. We hypothesise that the consumption frequency of organic and local food products may have increased during the lockdown. This unique situation of a generalised lockdown gives the opportunity to investigate how changes in food choice motives may have influenced the nutritional quality of the diet at an individual level. The results of this study may inform public health interventions that aim at tackling chronic diseases that are food related (obesity, diabetes, etc.) by identifying how food motives changes may increase or decrease the nutritional quality of the diet. Objectives Primary To examine the extent of changes in food choice motives during the lockdown and how they relate to changes in nutritional quality of the diet. Secondary To compare the consumption of organic and locally produced food before and during the lockdown and their relationships to changes in nutritional quality of the diet. Hypotheses Primary The lockdown had an impact on food choice motives, food consumption patterns and nutritional quality of individual diets in French consumers. Changes in food choice motives predicted changes in nutritional quality in French consumers. Secondary The lockdown increased the consumption of organic food in French consumers, which was associated to an increase in nutritional quality of the diet. The lockdown increased the consumption of locally produced food in French consumers which was associated to an increase in nutritional quality of the diet. Methods Procedure The study was run online and data were collected on April 30th and May 1st, 2020. Questionnaires were implemented on Qualtrics and participants were recruited by emailing individuals from a population registered in the Chemosens Platform’s PanelSens database. This database was declared to the relevant authority (Commission Nationale Informatique et Libertés; CNIL; n°1,148,039). Eligible participants were aged over 18 and have been residing in France at least since February 17th, 2020 (i.e., one month before the lockdown). Materials Baseline questionnaire Participants’ characteristics assessment included general socio-demographical questions (age, gender, department, living area, type of housing, highest educational qualification, employment status, financial situation), food-related questions (dietary restrictions, out-of-home eating habits, dieting status, weight, height), lockdown-related questions (professional situation, household composition, stress, depression and loneliness levels, grocery shopping habits, time spent cooking), COVID-related questions (being or having been ill, symptoms related to smell and taste, level of health concern). Food choice questionnaire Food choice motives during the month before lockdown and during the first month of lockdown was assessed using the adapted French version of the Food Choice Questionnaire [12]. It includes 24 items and nine subscales: health, mood, convenience, sensory appeal, natural content, price, weight control, familiarity and ethical concern. Instructions were adapted to assess food choice motives before and during lockdown. See Appendix C for the questionnaire in French. A score for each subscale before and during the lockdown will be computed by averaging ratings for individual items in each subscale. They will range from 1 to 4: 1 = Not at all important; 2 = A little important; 3 = Moderately important; 4 = Very important. Δ motives will be calculated as the difference of the score for each of the nine subscales during and before the lockdown, with Δ motives > 0: higher importance during lockdown, Δ motives < 0: lower importance during lockdown. Food frequency questionnaire Food consumption patterns were retrospectively assessed for the month before lockdown and the first month of lockdown using a food frequency questionnaire (FFQ) including 125 foods, 12 non-alcoholic drinks and 4 alcoholic drinks with frequency assessed by a 6-item scale from “Never” to “Several times a day” [13]. Participants were asked to estimate their usual portion size before and during the lockdown for 75 commonly eaten food items using photos on a 5-point scale derived from the SU.VI.MAX portion book [14]. For the 50 remaining food items, we will use the standard portion size. See Appendix D for the questionnaire in French. Consumption frequencies of each item before and during the lockdown will be transformed into daily frequencies and daily intake will be calculated by multiplying the daily frequency by the estimated portion size. Individual nutrients intake will then be calculated for all the participants before and during the lockdown by multiplying the daily intake of each food item by the nutritional values from the SU.VI.MAX nutrient composition database [15]. We will evaluate adherence to the French dietary recommendations during the month before lockdown and during the first month of lockdown using the simplified PNNS-GS2 (sPNNSGS-2), an index designed to reflect the 2017 French main dietary recommendations [16]. The sPNNS-GS2 builds on the distinction between malus components (less healthy food groups which consumption should be limited, carrying a negative score, i.e., red meat, processed meat, sugary foods, sweet-tasting beverages, alcoholic beverages, salt) and bonus components (healthier food groups carrying a positive score, i.e., fruits and vegetables, nuts, legumes, whole-grain food, milk and dairy products, fish and seafood, added fat below the threshold of 16% of total energy intake). A weight for each component is defined according to the level of evidence of the association between food groups consumption and health. Before and during the lockdown, sPNNSGS-2 scores will be computed for each participant as the sum of each component i multiplied by its associated weight and divided by its maximum absolute value. We will then calculate the difference in nutritional quality of the diets during and before the lockdown, with Δ quality > 0: better nutritional quality during lockdown, Δ quality < 0: poorer nutritional quality during lockdown). Organic and local food questionnaire Participants also answered questions about their consumption frequency of organic and local food products before and during the lockdown for 12 food categories on a 3-point scale: 2 = “Most of the time”, 1 = “Occasionally” and 0 = “Never” [17]. See Appendix E for the questionnaire in French. An organic consumption score and a local consumption score will be calculated as the mean across the 12 food categories. Δ organic and Δ local will be calculated as the difference of each score during and before the lockdown, with Δ organic / Δ local > 0: higher consumption during lockdown, Δ organic / Δ local < 0: lower consumption during lockdown. Statistical analyses All statistical analyses will be performed using SAS version 9.3 (SAS Institute, Inc., 2012 SAS® 9.3. Cary, NC). The level of significance will be set at p < 0.05 for primary and secondary analyses and at p < 0.01 for exploratory analyses. Definition of population for analysis Only participants who completed the entire study will be included in the analysis. Participants who failed one or more attention check out of the three included or who reported implausible energy intake (women: < 500 kcal/day or > 3500 kcal/day, men: < 800 kcal/day or > 4000 kcal/day [18], [19]) will be excluded. Descriptive analyses Socio-demographic characteristics of the participants will be reported. Continuous variables will be summarised using means and standard deviations. Categorical variables will be summarised using counts and percentages. Food choice motives scores, intake per food category (g/day) and sPNNGS-2 scores before and during the lockdown will be reported and compared (means, standard deviations, paired T-tests). Primary analyses Main model We will examine the influence of a change in food motives before and during the lockdown on the nutritional quality of the diet. Multiple linear regression will be used including the nine Δ motives as predictors and Δ quali