It's time to determine the cost of a healthy diet in Australia

Cost and Affordability of Habitual and Recommended Diets in Welfare-Dependent Households in Australia

It is crucial to ensure healthy diets are affordable in low socioeconomic groups, such as welfare-dependent households, who experience higher rates of diet-related disease than others. This study assessed the cost of habitual (unhealthy) and recommended (healthy) diets in six welfare-dependent and six other, comparable Australian households, using either popular branded products or the cheapest available alternatives. It also assessed diet affordability in welfare-dependent households, before and after modest increases in government welfare payments introduced in early September 2023. Results confirmed that recommended diets were less expensive than habitual diets in all households unless the cheapest available products were included. This strategy reduced habitual diet costs by 35-37% and recommended diet costs by 30-32%. The lower cost differential could aid perceptions that healthy foods are more expensive than unhealthy foods. In April 2023, 23-37% of the income of welfare-dependent households with children was required to purchase recommended diets; this reduced only to 20-35% in September 2023. Hence, the increases in welfare payments were insufficient to meaningfully improve the affordability of healthy diets in the most vulnerable Australians. In the current cost-of-living crisis, there is an urgent need for more welfare support to help purchase healthy diets. Monitoring of diet cost and affordability is also required.

Healthy Food Prices Increased More Than the Prices of Unhealthy Options during the COVID-19 Pandemic and Concurrent Challenges to the Food System

Food prices have escalated due to impacts of the COVID-19 pandemic on global food systems, and other regional shocks and stressors including climate change and war. Few studies have applied a health lens to identify the most affected foods. This study aimed to assess costs and affordability of habitual (unhealthy) diets and recommended (healthy, equitable and more sustainable) diets and their components in Greater Brisbane, Queensland, Australia from 2019 to 2022 using the Healthy Diets Australian Standardised Affordability and Pricing protocol. Affordability was determined for reference households at three levels of income: median, minimum wage, and welfare-dependent. The recommended diet cost increased 17.9%; mostly in the last year when the prices of healthy foods, such as fruit, vegetables and legumes, healthy fats/oils, grains, and meats/alternatives, increased by 12.8%. In contrast, the cost of the unhealthy foods and drinks in the habitual diet 'only' increased 9.0% from 2019 to 2022, and 7.0% from 2021 to 2022. An exception was the cost of unhealthy take-away foods which increased by 14.7% over 2019-2022. With government COVID-19-related payments, for the first time recommended diets were affordable for all and food security and diets improved in 2020. However, the special payments were withdrawn in 2021, and recommended diets became 11.5% less affordable. Permanently increasing welfare support and providing an adequate minimum wage, while keeping basic, healthy foods GST-free and increasing GST to 20% on unhealthy foods, would improve food security and diet-related health inequities. Development of a Consumer Price Index specifically for healthy food would help highlight health risks during economic downturns.

Trends and Factors Associated with Obesity Prevalence in Rural Australian Adults-Comparative Analysis of the Crossroads Studies in Victoria over 15 Years

This study examined the changes in the prevalence of obesity and associated lifestyle factors using data from repeated cross-sectional, self-reported surveys (Crossroads I: 2001-2003 and Crossroads II: 2016-2018, studies) and clinic anthropometric measurements collected from regional and rural towns in the Goulburn Valley, Victoria. Given that past community studies have only focused categorically on dietary intake, or assessed caloric energy intake, we examined the difference in broad dietary practices at two different times. Clinical assessments from randomly selected household participants aged ≥18 years were analyzed. Differences in obesity prevalence were calculated for each individual variable. Logistic regression was used to determine the odds ratios (95% confidence intervals (CI)) with and without adjustment for key lifestyle factors. There were 5258 participants in Crossroads I and 2649 in Crossroads II surveys. Obesity prevalence increased from 28.2% to 30.8% over 15 years, more among those who ate fried food, but decreased significantly among rural dwellers (31.7: 27.0, 36.8% versus 25.1: 22.9, 27.5%) and those who had adequate fruit intake (28.5: 25.0, 32.3% to 23.9: 21.8, 26.2%). Obesity was associated with older age (≥35 years), use of fat-based spreads for bread (adjusted odds ratio, aOR:1.26: 1.07, 1.48) and physical inactivity. The increase in obesity prevalence especially in the rural towns, was associated with unhealthy dietary behaviour which persisted over 15 years. Understanding and addressing the upstream determinants of dietary intake and choices would assist in the development of future health promotion Programs.

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.

Cost and accessibility of empiric food elimination diets for treatment of eosinophilic oesophagitis

AIM

This study aimed to investigate and compare the cost, affordability, and accessibility of three elimination diet approaches for the treatment of patients with eosinophilic esophagitis: the two-, four- and six-food elimination diets and with comparison to a standard diet.

METHODS

An evidence-based modelling process was undertaken for costing and accessibility, including the development of three hypothetical reference families; four food baskets were modified from an established benchmark for each diet. Baskets were costed across eastern Melbourne, Australia. Affordability was modelled using two incomes: the equivalised disposable household income and welfare payments for reference families. Affordability was defined as <30% of the median weekly household income and food stress defined as >25% of a median weekly household income.

RESULTS

All elimination diets were significantly more expensive than a standard diet and may be unaffordable for those receiving welfare. Prices significantly increased as the number of food allergens eliminated increased. Most items for a two-food elimination diet were available at major supermarkets; however, items for nutritionally complete four- and six-food elimination diets required a visit to a second store.

CONCLUSION

A step-up approach, commencing with a two-food elimination diet, instead of starting with a six-food elimination diet, may alleviate affordability barriers for most family types, which may enhance compliance. Clinicians should consider family type, financial situation, as well as accessibility of allergen-free foods in the patient's residential area when deciding on the most appropriate dietary or therapeutic treatment approach for eosinophilic oesophagitis.

Cost and Affordability of Healthy, Equitable and Sustainable Diets in Low Socioeconomic Groups in Australia

Few Australians consume a healthy, equitable and more sustainable diet consistent with the Australian Dietary Guidelines (ADGs). Low socioeconomic groups (SEGs) suffer particularly poor diet-related health problems. However, granular information on dietary intakes and affordability of recommended diets was lacking for low SEGs. The Healthy Diets Australian Standardised Affordability and Pricing protocol was modified for low SEGs to align with relevant dietary intakes reported in the National Nutrition Survey 2011–2012(which included less healthy and more discretionary options than the broader population), household structures, food purchasing habits, and incomes. Cost and affordability of habitual and recommended diets of low SEGs were calculated using prices of ‘standard brands’ and ‘cheapest options’. With ‘standard brands’, recommended diets cost less than habitual diets, but were unaffordable for low SEGs. With ‘cheapest options’, both diets were more affordable, but recommended diets cost more than habitual diets for some low SEGs, potentially contributing to perceptions that healthy food is unaffordable. The study confirms the need for an equity lens to better target dietary guidelines for low SEGs. It also highlights urgent policy action is needed to help improve affordability of recommended diets.

Affordability of current, and healthy, more equitable, sustainable diets by area of socioeconomic disadvantage and remoteness in Queensland: insights into food choice

Background

Poor diet is the leading preventable risk factor contributing to the burden of disease globally and in Australia, and is inequitably distributed. As the price of healthy foods is a perceived barrier to improved diets, evidence on the cost and affordability of current (unhealthy) and recommended (healthy, more equitable and sustainable) diets is required to support policy action.

Methods

This study applied the Healthy Diets ASAP (Australian Standardised Affordability and Pricing) methods protocol to measure the cost, cost differential and affordability of current and recommended diets for a reference household in Queensland, Australia. Food prices were collected in 18 randomly selected locations stratified by area of socioeconomic disadvantage and remoteness. Diet affordability was calculated for three income categories.

Results

Surprisingly, recommended diets would cost 20% less than the current diet in Queensland as a whole. Households spent around 60% of their food budget on discretionary choices (that is, those not required for health that are high in saturated fat, added sugar, salt and/or alcohol). Queensland families would need to spend around 23% of their income on recommended diets. However, recommended diets would not be affordable in low socioeconomic or very remote areas, costing 30 and 35% of median household income respectively. The government supplements due to the SARS-CoV-2 pandemic would improve affordability of recommended diets by 29%.

Conclusions

Study findings highlight that while price is one factor affecting consumer food choice, other drivers such as taste, convenience, advertising and availability are important. Nevertheless, the study found that recommended diets would be unaffordable in very remote areas, and that low-income families are likely experiencing food stress, irrespective of where they live in Queensland. Policy actions, such as increasing to 20% the current 10% tax differential between basic healthy, and unhealthy foods in Australia, and supplementing incomes of vulnerable households, especially in remote areas, are recommended to help improve diet equity and sustainability, and health and wellbeing for all.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-021-01481-8.

Identifying trends over time in food affordability: The Illawarra Healthy Food Basket survey, 2011-2019

OBJECTIVE

To determine the affordability of a healthy food basket (HFB) for welfare recipients and average income earners in 2019 and to compare trends from 2011.

METHODS

Fifty-seven food items' prices were collected from fifteen stores across five suburbs representing low, medium and high socio-economic status. Costs were compared with average weekly income and welfare payments to assess the baskets' affordability for a family of four and five.

RESULTS

In 2019, a HFB was affordable (below 30% of household income) for a five-person reference family with a pensioner, representing 24.8% of weekly welfare payments, but not for a four-person reference family (33.0%). The cost of the HFB increased slightly over time from AU$288.91 in 2011 to AU$291.79 in 2019. The food affordability improved for a family of five including a pensioner over this period due to an increase of average weekly earnings and welfare payments.

CONCLUSION

In 2019, the HFB was affordable for a five-person family; however, a four-person family receiving welfare benefits would have experienced significant "food stress," with the food basket costing above 30% of household income.

IMPLICATIONS FOR HEALTH PROMOTION

Inequity in the affordability of healthy food is a major public health concern and one that demands recognition and national action. The impact of policies affecting welfare support and wages needs to be considered, as well as food pricing strategies and possible food subsidies for those at greatest risk of food insecurity.

A systematic scoping review of the habitual dietary costs in low socioeconomic groups compared to high socioeconomic groups in Australia

Background

Low socioeconomic groups (SEGs) in Australia are less likely to consume diets consistent with the Australian Dietary Guidelines (ADGs) and suffer poorer health than the broader population. The unaffordability, or perceived high cost, of healthy diets may be a factor. Detailed data on the cost of habitually consumed diets is required in order to inform strategies to alleviate socioeconomic impacts on dietary intake.

This systematic scoping review aims to identify the cost of the habitual dietary intake of low SEGs in Australia, in terms of the whole diet and its composite foods, in comparison to the cost in higher SEGs.

Methods

A systematic search of peer-reviewed literature since 2000 and key government and non-government organisation (NGO) websites was undertaken. Data were extracted, synthesised and analysed in relation to study populations, dietary cost assessment measures, socioeconomic measures, and dietary cost and affordability.

Results

The review identified four studies meeting inclusion criteria. Results confirmed that overall, low SEGs spend a lower amount, yet a higher proportion of household income, on food and drinks than higher SEGs. Quantitative comparison of the dietary costs between included studies was not possible due to difference in populations and study metrics. Costs of the habitual diet in these studies were not reported for ADG food groups, so did not allow for assessment of the healthfulness of the dietary intake or comparison with costs of recommended diets at food group level.

Conclusions

Existing research does not provide sufficiently granular data of the costs of habitual diets of low SEGs in comparison to higher SEGs or data in a form that can inform strategies and interventions to improve dietary intake and diet-related health of low SEGs in Australia. Future empirical health research requires more granular measures of habitual spending on ADG food groups across SEGs.

The affordability of a healthy and sustainable diet: an Australian case study

BACKGROUND/AIMS

EAT-Lancet Commission's Planetary Health Diet proposed a diet that integrates nutrition and sustainability considerations, however its affordability is unknown in many country-specific contexts, including Australia. The aim of this study is to develop a healthy and sustainable food basket modelled on the Planetary Health Diet to determine the affordability of the Planetary Health Diet basket across various socio-economic groups, and compare this affordability with a food basket modelled on the typical current diet, in an Australian setting.

METHODS

An Australian-specific Planetary Health Diet basket was developed for a reference household (2 adults and 2 children) modelled on the Planetary Health Diet reference diet, and compared to a previously-developed Typical Australian Diet basket. The cost of each food basket was determined by online supermarket shopping surveys in low, medium and high socio-economic areas in each Australian state. Basket affordability was determined for the reference household by comparing the basket cost to disposable income in each socio-economic group in each state. Mann-Whitney U tests then determined if there were significant differences between the median costs and the median affordability of both baskets.

RESULTS

The Planetary Health Diet basket was shown to be less expensive and more affordable than the Typical Australian Diet basket nationally, in all metropolitan areas, in all socio-economic groups across Australia (median cost: Planetary Health Diet = AUD$188.21, Typical Australian Diet = AUD$224.36; median affordability: Planetary Health Diet = 13%, Typical Australian Diet = 16%; p = < 0.05).

CONCLUSIONS

This study showed the Planetary Health Diet to be more affordable than the Typical Australian Diet for metropolitan-dwelling Australians.

IMPLICATIONS

These results can help to inform public health and food policy aimed at achieving a healthy and sustainable future for all Australians, including reductions in overweight/obesity rates and increased food security.

A tale of two cities: the cost, price-differential and affordability of current and healthy diets in Sydney and Canberra, Australia

BACKGROUND

The perception that healthy foods are more expensive than unhealthy foods has been reported widely to be a key barrier to healthy eating. However, assessment of the relative cost of healthy and unhealthy foods and diets is fraught methodologically. Standardised approaches to produce reliable data on the cost of total diets and different dietary patterns, rather than selected foods, are lacking globally to inform policy and practice.

METHODS

This paper reports the first application, in randomly selected statistical areas stratified by socio-economic status in two Australian cities, of the Healthy Diets Australian Standardized Affordability and Pricing (ASAP) method protocols: diet pricing tools based on national nutrition survey data and dietary guidelines; store sampling and location; determination of household incomes; food price data collection; and analysis and reporting. The methods were developed by the International Network on Food and Obesity/NCD Research, Monitoring and Action Support (INFORMAS) as a prototype of an optimum approach to assess, compare and monitor the cost and affordability of diets across different geographical and socio-economic settings and times.

RESULTS

Under current tax policy in Australia, healthy diets would be 15-17% less expensive than current (unhealthy) diets in all locations assessed. Nevertheless, healthy diets are likely to be unaffordable for low income households, costing more than 30% of disposable income in both cities surveyed. Households spent around 58% of their food budget on unhealthy food and drinks. Food costs were on average 4% higher in Canberra than Sydney, and tended to be higher in high socioeconomic locations.

CONCLUSIONS

Health and fiscal policy actions to increase affordability of healthy diets for low income households are required urgently. Also, there is a need to counter perceptions that current, unhealthy diets must be less expensive than healthy diets. The Healthy Diets ASAP methods could be adapted to assess the cost and affordability of healthy and unhealthy diets elsewhere.

Food Insecurity and Socioeconomic Disadvantage in Australia

Research on food insecurity in Australia has typically relied on a single-item measure and finds that approximately 5% of the population experiences food insecurity. This research also finds that demographic characteristics such as household composition and marital status affect levels of food insecurity, independent of income level. The present study examines the prevalence and correlates of food insecurity in a cohort (n = 400) of people experiencing entrenched disadvantage in Perth, Western Australia. Using the US Department of Agriculture Household Food Security Survey Module, we find that food insecurity at the household, adult, and child level is at sharply elevated levels, with 82.8% of the sample reporting household food insecurity, 80.8% and 58.3% experiencing food insecurity among adults and children, respectively. Demographic characteristics do not significantly affect levels of food insecurity, and food insecurity is associated with negative physical and mental health outcomes. Food insecurity is positively correlated with access to food emergency relief services, indicating that these services are being used by those most in need, but do not address the root causes of food insecurity. Policy and practice should focus on increasing stable access to adequate quantities and quality of food and addressing the structural causes of food insecurity.

Healthy Diets in Rural Victoria-Cheaper than Unhealthy Alternatives, Yet Unaffordable

Rural communities experience higher rates of obesity and reduced food security compared with urban communities. The perception that healthy foods are expensive contributes to poor dietary choices. Providing an accessible, available, affordable healthy food supply is an equitable way to improve the nutritional quality of the diet for a community, however, local food supply data are rarely available for small rural towns. This study used the Healthy Diets ASAP tool to assess price, price differential and affordability of recommended (healthy) and current diets in a rural Local Government Area (LGA) (pop ≈ 7000; 10 towns) in Victoria, Australia. All retail food outlets were surveyed (n = 40). The four most populous towns had supermarkets; remaining towns had one general store each. Seven towns had café/take-away outlets, and all towns had at least one hotel/pub. For all towns the current unhealthy diet was more expensive than the recommended healthy diet, with 59.5% of the current food budget spent on discretionary items. Affordability of the healthy diet accounted for 30⁻32% of disposable income. This study confirms that while a healthy diet is less expensive than the current unhealthier diet, affordability is a challenge for rural communities. Food security is reduced further with restricted geographical access, a limited healthy food supply, and higher food prices.

Healthy diets ASAP - Australian Standardised Affordability and Pricing methods protocol

BACKGROUND

This paper describes the rationale, development and final protocol of the Healthy Diets Australian Standardised Affordability and Pricing (ASAP) method which aims to assess, compare and monitor the price, price differential and affordability of healthy (recommended) and current (unhealthy) diets in Australia. The protocol is consistent with the International Network for Food and Obesity / non-communicable Diseases Research, Monitoring and Action Support's (INFORMAS) optimal approach to monitor food price and affordability globally.

METHODS

The Healthy Diets ASAP protocol was developed based on literature review, drafting, piloting and revising, with key stakeholder consultation at all stages, including at a national forum.

DISCUSSION

The protocol was developed in five parts. Firstly, for the healthy (recommended) and current (unhealthy) diet pricing tools; secondly for calculation of median and low-income household incomes; thirdly for store location and sampling; fourthly for price data collection, and; finally for analysis and reporting. The Healthy Diets ASAP protocol constitutes a standardised approach to assess diet price and affordability to inform development of nutrition policy actions to reduce rates of diet-related chronic disease in Australia. It demonstrates application of the INFORMAS optimum food price and affordability methods at country level. Its wide application would enhance monitoring and utility of dietary price and affordability data from a health perspective in Australia. The protocol could be adapted in other countries to monitor the price, price differential and affordability of current and healthy diets.

Socioeconomic differences in the cost, availability and quality of healthy food in Sydney

OBJECTIVE

To compare the cost of a basket of staple foods, together with the availability and quality of fresh fruit and vegetables, by supermarket store type in high and low socioeconomic suburbs of Sydney.

METHODS

A food basket survey was undertaken in 100 supermarkets in the 20 highest and 20 lowest socioeconomic suburbs of Sydney. We assessed the cost of 46 foods, the range of 30 fresh fruit and vegetables and the quality of ten fresh fruit and vegetables. Two major supermarket retailers, a discount supermarket chain and independent grocery stores were surveyed.

RESULTS

The food basket was significantly cheaper in low compared to high socioeconomic suburbs ($177 vs $189, p<0.01). Discount supermarkets were at least 30% cheaper than other supermarket stores. There were fewer varieties and poorer quality fruit and vegetables in stores in low socioeconomic suburbs.

CONCLUSIONS

Food basket prices and the availability and quality of fruit and vegetables varied significantly by store type and socioeconomic status of suburb. Implications for public health: A nationwide food and nutrition surveillance system is required to inform public health policy and practice initiatives. In addition to the food retail environment, these initiatives must address the underlying contributors to inequity and food insecurity for disadvantaged groups.

Costing ‘healthy’ food baskets in Australia – a systematic review of food price and affordability monitoring tools, protocols and methods

Objective

To undertake a systematic review to determine similarities and differences in metrics and results between recently and/or currently used tools, protocols and methods for monitoring Australian healthy food prices and affordability.

Design

Electronic databases of peer-reviewed literature and online grey literature were systematically searched using the PRISMA approach for articles and reports relating to healthy food and diet price assessment tools, protocols, methods and results that utilised retail pricing.

Setting

National, state, regional and local areas of Australia from 1995 to 2015.

Subjects

Assessment tools, protocols and methods to measure the price of ‘healthy’ foods and diets.

Results

The search identified fifty-nine discrete surveys of ‘healthy’ food pricing incorporating six major food pricing tools (those used in multiple areas and time periods) and five minor food pricing tools (those used in a single survey area or time period). Analysis demonstrated methodological differences regarding: included foods; reference households; use of availability and/or quality measures; household income sources; store sampling methods; data collection protocols; analysis methods; and results.

Conclusions

‘Healthy’ food price assessment methods used in Australia lack comparability across all metrics and most do not fully align with a ‘healthy’ diet as recommended by the current Australian Dietary Guidelines. None have been applied nationally. Assessment of the price, price differential and affordability of healthy (recommended) and current (unhealthy) diets would provide more robust and meaningful data to inform health and fiscal policy in Australia. The INFORMAS ‘optimal’ approach provides a potential framework for development of these methods.

A comparison of the cost of generic and branded food products in Australian supermarkets

OBJECTIVE

Food cost is an important factor influencing the consumption of nutritious foods and subsequent chronic disease risk. The present study compared the cost of branded food products with their generic equivalents across a range of food categories.

SETTING

The survey was conducted within two major supermarket chains across six locations in Sydney, Australia (n 12).

DESIGN

Price differences were calculated for 'core' (nutrient dense and low in energy) and 'extra' (high in undesirable nutrients and/or energy) packaged foods (n 22) between generic and branded items.

RESULTS

A cost saving of 44 % was found by purchasing generic over branded products across all food categories. The most significant savings were for core foods, such as bread and cereals, and the smallest cost savings were seen for fruit products. There was little variation in cost saving between branded and generic products by socio-economic status of the supermarket location.

CONCLUSIONS

The large price differential between branded and generic food products implies that consumers, particularly those on lower incomes, could benefit financially from purchasing generic items. The promotion of core generic products may be an effective strategy to assist people on lower incomes to meet dietary guidelines.

Monitoring the affordability of healthy eating: a case study of 10 years of the Illawarra Healthy Food Basket

Healthy food baskets have been used around the world for a variety of purposes, including: examining the difference in cost between healthy and unhealthy food; mapping the availability of healthy foods in different locations; calculating the minimum cost of an adequate diet for social policy planning; developing educational material on low cost eating and examining trends on food costs over time. In Australia, the Illawarra Healthy Food Basket was developed in 2000 to monitor trends in the affordability of healthy food compared to average weekly wages and social welfare benefits for the unemployed. It consists of 57 items selected to meet the nutritional requirements of a reference family of five. Bi-annual costing from 2000–2009 has shown that the basket costs have increased by 38.4% in the 10-year period, but that affordability has remained relatively constant at around 30% of average household incomes.

Longitudinal study of Consumer Price Index (CPI) trends in core and non-core foods in Australia

OBJECTIVE

This study examined trends in the price of healthy and less-healthy foods from 1989 to 2007 using the Australian Consumer Price Index (CPI).

METHODS

CPI food expenditure classes were classified as 'core' or 'non-core'. Trends in the CPI were analysed to examine the rise in prices of core compared with non-core foods.

RESULTS

On average, the CPI for core foods has risen at a slightly higher, though not statistically significant, rate than non-core foods. Furthermore, selected groupings reveal interesting patterns. 'Bread' has risen in price significantly more than 'cakes and biscuits', and 'milk' has risen in price significantly more than 'soft drinks, waters and juices'.

CONCLUSIONS AND IMPLICATIONS

This investigation of food price trends reveals notable differences between core and non-core foods. This should be investigated further to determine the extent to which this contributes to the higher prevalence of diet-related diseases in low socio-economic groups.