Estimating dietary costs of low-income women in California: a comparison of 2 approaches

Cost of a healthy diet: A population-representative comparison of three diet cost methods in Canada

INTRODUCTION

Different food price sources and dietary assessment tools may impact the estimation of diet costs and hamper our understanding of the relationship between diet costs and dietary intakes. We investigated the effect of three diet cost derivation methods, with increasing numbers of food prices and geographic specificity, holding consistent the dietary assessment, on the estimation of diet costs overall and by food group.

METHODS

We matched 24-hour dietary recall data from the 2015 Canadian Community Health Survey-Nutrition (CCHS-N) to food price data from three Canadian Consumer Price Index (CPI) food price lists; national short list, national long list, and provincial long list. We compared the daily ($/day) and energy-adjusted ($/2,000kcal) diet costs overall and by food groups for the overall population (4+), children (4-18), and adults (19+).

RESULTS

The proportion of dietary intakes (g) that were covered by CPI prices significantly increased from the national short list to the national long list but did not significantly differ from the national long list to the provincial long list. The national short list resulted in the highest daily and energy-adjusted diet costs overall. No difference in diet costs was noted between the national and provincial long lists. Diet costs for four food groups-additions, sweets, fruits, and vegetables, which were poorly covered by the national short list-significantly differed using the national and provincial long lists. All three diet cost methods were significantly correlated with energy intakes; however, a strong/very strong correlation was detected for children, and a weak/moderate correlation for adults.

CONCLUSION

The choice of food price data may introduce bias in the diet cost estimate, as well as limiting our understanding of how individuals allocate their diet costs. Refinement of diet cost estimation methodology and measures can strengthen future studies of how consumers allocate their purchases to their diets.

Assessing the Cost of Healthy and Unhealthy Diets: A Systematic Review of Methods

PURPOSE OF REVIEW

Poor diets are a leading risk factor for chronic disease globally. Research suggests healthy foods are often harder to access, more expensive, and of a lower quality in rural/remote or low-income/high minority areas. Food pricing studies are frequently undertaken to explore food affordability. We aimed to capture and summarise food environment costing methodologies used in both urban and rural settings.

RECENT FINDINGS

Our systematic review of high-income countries between 2006 and 2021 found 100 relevant food pricing studies. Most were conducted in the USA (n = 47) and Australia (n = 24), predominantly in urban areas (n = 74) and cross-sectional in design (n = 76). All described a data collection methodology, with just over half (n = 57) using a named instrument. The main purpose for studies was to monitor food pricing, predominantly using the 'food basket', followed by the Nutrition Environment Measures Survey for Stores (NEMS-S). Comparatively, the Healthy Diets Australian Standardised Affordability and Price (ASAP) instrument supplied data on relative affordability to household incomes. Future research would benefit from a universal instrument reflecting geographic and socio-cultural context and collecting longitudinal data to inform and evaluate initiatives targeting food affordability, availability, and accessibility.

Development of the Healthy Purchase Index (HPI): a scoring system to assess the nutritional quality of household food purchases

OBJECTIVE

To develop an index to assess the nutritional quality of household food purchases based on food expenditures only.

DESIGN

A database of monthly food purchases of a convenience sample of low-income households was used to develop the Healthy Purchase Index (HPI). The HPI is the sum of two sub-scores based on expenditure shares of food categories in total household food expenditure: the purchase diversity sub-score and the purchase quality sub-score. The first was adapted from an existing diversity score. The second integrated those food categories identified as the best predictors of the nutritional quality of purchases based on associations between expenditure shares of food categories and two nutritional quality indicators: the mean adequacy ratio (MAR) and the mean excess ratio (MER). Correlation between the HPI and a score assessing adherence to French dietary guidelines (PNNS-GSmod) was performed as a first validation.Setting/ParticpantsFood purchases of 112 households from deprived neighbourhoods of Marseille (France), participating in the Opticourses and Jassur projects (2012-2015).

RESULTS

The purchase diversity sub-score reflects the presence in food purchases of five food categories: fruits, vegetables, starches, dairy products, and meat, fish & eggs. The purchase quality sub-score is based on expenditure shares for fruit & vegetables, added fats & seasonings, sweet snacks, cheese, sugary drinks, refined grains and fish, as these were identified as predictors of the nutritional quality of purchases. The HPI was positively associated with the PNNS-GSmod (r s=0·378; P<0·001).

CONCLUSIONS

The HPI helps assess the healthiness of household food purchases.

Accessibility and Affordability of Supermarkets: Associations With the DASH Diet

INTRODUCTION

It is unknown whether there is an interplay of affordability (economic accessibility) and proximity (geographic accessibility) of supermarkets in relation to having a Dietary Approaches to Stop Hypertension (DASH)-accordant diet.

METHODS

Data (collected: 2005-2015, analyzed: 2016) were from the cross-sectional, population-based Fenland Study cohort: 9,274 adults aged 29-64 years, living in Cambridgeshire, United Kingdom. Dietary quality was evaluated using an index of DASH dietary accordance, based on recorded consumption of foods and beverages in a validated 130-item, semi-quantitative food frequency questionnaire. DASH accordance was defined as a DASH score in the top quintile. Dietary costs (£/day) were estimated by attributing a food price variable to the foods consumed according to the questionnaire. Individuals were classified as having low-, medium-, or high-cost diets. Supermarket affordability was determined based on the cost of a 101-item market basket. Distances between home address to the nearest supermarket (geographic accessibility) and nearest economically-appropriate supermarket (economic accessibility) were divided into tertiles.

RESULTS

Higher-cost diets were more likely to be DASH-accordant. After adjustment for key demographics and exposure to other food outlets, individuals with lowest economic accessibility to supermarkets had lower odds of being DASH-accordant (OR=0.59, 95% CI=0.52, 0.68) than individuals with greatest economic accessibility. This association was stronger than with geographic accessibility alone (OR=0.85, 95% CI=0.74, 0.98).

CONCLUSIONS

Results suggest that geographic and economic access to food should be taken into account when considering approaches to promote adherence to healthy diets for the prevention of cardiovascular diseases and other chronic disease.

The Challenge in Improving the Diets of Supplemental Nutrition Assistance Program Recipients: A Historical Commentary

This paper provides a historical background for the current nutrition issues faced by the Supplemental Nutrition Assistance Program (SNAP). The Food Stamp Program evolved into SNAP during a period when U.S. diets, particularly those of the poor, became less healthful. During the 1960s, the U.S. (Kennedy-Johnson era) addressed malnutrition first with a pilot project focused on retail sales and cash food stamps, which showed that low-income consumers purchased relatively healthy foods for a fairly high-quality diet. Southern politicians in the House of Representatives wanted a program similar to an earlier subsidized commodity distribution program. The pilot provided the evidence northern urban politicians sought, and they held the farm bill hostage until southern rural interests agreed to an unfettered Food Stamp Program that allowed purchases directly from retailers. A final Food Stamp Program law was incorporated into the farm bill and passed. This program shifted in 1977 to a full cash benefit system later, first using food stamps to act as cash and later an Electronic Benefit Transfer program. The program was designed at a time of a very healthful diet of lower-SES Americans. As diets of lower-income Americans changed and the entire food system shifted, the program has not been adjusted in any manner. Today, 50%-66% of the calories in the American diet, particularly that of low-SES Americans, come from highly processed foods containing excessive refined carbohydrates, sodium, unhealthy saturated fats, and added sugar. The SNAP design has not responded to these shifts in diet and the powerful interests controlling our food system. This twist in the U.S. diet and food system presents a major dilemma to those attempting to form a healthy food program based on the results of an effective pilot project.

Contribution of food prices and diet cost to socioeconomic disparities in diet quality and health: a systematic review and analysis

CONTEXT

It is well established in the literature that healthier diets cost more than unhealthy diets.

OBJECTIVE

The aim of this review was to examine the contribution of food prices and diet cost to socioeconomic inequalities in diet quality.

DATA SOURCES

A systematic literature search of the PubMed, Google Scholar, and Web of Science databases was performed.

STUDY SELECTION

Publications linking food prices, dietary quality, and socioeconomic status were selected.

DATA EXTRACTION

Where possible, review conclusions were illustrated using a French national database of commonly consumed foods and their mean retail prices.

DATA SYNTHESIS

Foods of lower nutritional value and lower-quality diets generally cost less per calorie and tended to be selected by groups of lower socioeconomic status. A number of nutrient-dense foods were available at low cost but were not always palatable or culturally acceptable to the low-income consumer. Acceptable healthier diets were uniformly associated with higher costs. Food budgets in poverty were insufficient to ensure optimum diets.

CONCLUSIONS

Socioeconomic disparities in diet quality may be explained by the higher cost of healthy diets. Identifying food patterns that are nutrient rich, affordable, and appealing should be a priority to fight social inequalities in nutrition and health.

Higher nutritional quality at no additional cost among low-income households: insights from food purchases of "positive deviants"

BACKGROUND

It is unknown whether diet quality is correlated with actual food expenditure. According to the positive deviance theory, the study of actual food expenditure by people with limited economic resources could help identify beneficial food-purchasing behavior.

OBJECTIVES

The aims were to investigate the relation between actual expenditure on food and nutritional quality and to identify "positive deviants" among low-income households.

DESIGN

Individuals in deprived social situations (n = 91) were recruited as part of the "Opticourses" nutrition intervention conducted in 2012-2014 in poor districts of Marseille, France. Opticourses participants collected food-purchase receipts for their household over a 1-mo period. "Actual diet costs" and "estimated diet costs" were calculated per 2000 kcal of food purchases by using actual expenditures and a standard food price database of food consumed by a representative sample of French adults, respectively. Mean adequacy ratio (MAR), mean excess ratio (MER), and energy density (ED) were used as nutritional quality indicators. "Positive deviants" were defined as having a higher MAR and a lower MER than the respective median values.

RESULTS

Opticourses participants selected less-expensive food options than the average French population, both within a food group and for a given food item. Higher diet costs were associated with higher nutritional quality (higher MAR, lower ED), regardless of whether costs were calculated from actual expenditure or on the basis of standard food prices. Twenty-one positive deviants were identified. They made significantly healthier purchases than did other participants (MAR: +13%; MER: -90%. ED: -22%) at higher estimated diet costs. Yet, they did not spend more on food (having the same actual diet costs), which showed that they purchased food with a higher nutritional quality for their price.

CONCLUSION

In this low-income population, actual diet cost was positively correlated with nutritional quality, yet the results showed that higher diet quality is not necessarily more costly when foods with higher nutritional quality for their price are selected. The Opticourses intervention was registered at clinicaltrials.gov as NCT02383875.

Vegetable variety is a key to improved diet quality in low-income women in California

Primary prevention education interventions, including those sponsored by the US Department of Agriculture for low-income families, encourage and support increases in vegetable intake. Promoting vegetable variety as a focal point for behavior change may be a useful strategy to increase vegetable consumption. A simple vegetable variety evaluation tool might be useful to replace the time-intensive 24-hour dietary recall. The purpose of our study was to determine whether vegetable variety is associated with vegetable consumption and diet quality among US Department of Agriculture program participants. Variety of vegetable intake and measures of total vegetable intake, diet quality, and diet cost were evaluated. Low-income, female participants (N=112) aged 20 to 55 years with body mass index 17.7 to 68.5 who were the primary food purchasers/preparers for their households were recruited from four California counties representing rural, urban, and suburban areas. Energy density and Healthy Eating Index-2005 were used to assess diet quality. Vegetable variety was based on number of different vegetables consumed per week using a food frequency questionnaire, and three groups were identified as: low variety, ≤5 different vegetables per week; moderate variety, 6 to 9 vegetables per week; and high variety, ≥10 vegetables per week. Compared with the low-variety group, participants in the high-variety group ate a greater quantity of vegetables per day (P<0.001); their diets had a higher Healthy Eating Index score (P<0.001) and lower energy density (P<0.001); and costs of their daily diet and vegetable use were higher (P<0.001). Thus, greater vegetable variety was related to better overall diet quality, a larger quantity of vegetables consumed, and increased diet cost.

Comparability of methods assigning monetary costs to diets: derivation from household till receipts versus cost database estimation using 4-day food diaries

BACKGROUND/OBJECTIVES

Diet cost could influence dietary patterns, with potential health consequences. Assigning a monetary cost to diet is challenging, and there are contrasting methods in the literature. This study compares two methods-a food cost database linked to 4-day diet diaries and an individual cost calculated from household till receipts.

SUBJECTS/METHODS

The Diet and Nutrition Tool for Evaluation (DANTE) had supermarket prices (cost per 100 g) added to its food composition table. Agreement between diet costs calculated using DANTE from food diaries and expenditure recorded using food purchase till receipts for 325 individuals was assessed using correlation and Bland Altman (BA) plots.

RESULTS

The mean difference between the methods' estimates was £0.10. The BA showed 95% limits of agreement of £2.88 and -£3.08. Excluding the highest 5% of diet cost values from each collection method reduced the mean difference to £0.02, with limits of agreement ranging from £2.31 to -£2.35. Agreement between the methods was stronger for males and for adults.

CONCLUSIONS

Diet cost estimates using a food price database with 4-day food diaries are comparable to recorded expenditure from household till receipts at the population or group level. At the individual level, however, estimates differed by as much as £3.00 per day. The methods agreed less when estimating diet costs of children, females or those with more expensive diets.