The correlation between socioeconomic status and healthy diets: An overview
Socioeconomic status (SES) has had a strong influence on diet quality, a claim recognized since the 1930s and one that is well supported by epidemiologic data.1 The affluent have more access to higher-quality, nutrient-dense but typically more expensive food while the underprivileged are often forced to choose cheaper, energy-dense food options. Today’s soaring food prices tend to increase the disparities in diet seen across the socioeconomic gradient. While the total spending for food has increased across all households, the proportion of food cost to household income is grossly disproportionate for affluent versus underprivileged households. The average American household spends 11% of disposable income on food, while those below the poverty line spend 25%; 2006 data from France shows that wealthy households spend 22% of disposable income on food while less-affluent ones spend 29%.2
Economic considerations have a significant impact on food choices and are particularly evident among the less affluent. Studies have shown that lower-income groups tend to make cheaper food choices. Unfortunately, these low-cost food choices are also less healthy. Fruits and vegetables, while viewed as healthy by lower-income groups, are also deemed less affordable or unaffordable; it follows that, compared to poorer families, wealthier families consume more fruits and vegetables of greater variety.1 Meat consumption is comparable between affluent and poor households in terms of quantity, but lower-income families tend to choose cheaper and fattier cuts.2
In general, low-cost, lower-quality foods tend to be energy-dense. These contain refined grains and added sugars and fats and are cheaper per calorie compared to nutrient-dense foods. This is true across multiple countries, as epidemiological data confirms.2
Foods that are perceived to be nutritious are often of higher quality and are more nutrient-dense. The greater nutrient density of these foods mean that they have a higher cost per calorie (and are therefore more expensive) than energy-dense foods.2
How does the correlation between SES and diet affect health?
Healthy diets with whole grains, lean meats, fish, low-fat dairy products and fresh vegetables and fruit are more likely to be consumed by groups of higher SES. Diets rich in these types of foods are associated with a lower risk of compromising heart health or a healthy body weight.
Lower-income families across different countries tend to select diets based on price; the foods they choose are cheaper, more energy-dense and contain few vegetables and fruit. These choices may lead to inadequate intakes of key micronutrients and poverty-driven hidden hunger, as well as the overconsumption of calories and a rise in obesity rates.2
Poor diet choices also have a great impact on pregnant women and the children they carry. Adequate and appropriate nutrition during the peri-conceptual and ante-natal periods is a particularly important determinant of health in both mother and child. The consequences of undernutrition and micronutrient deficiencies during the first 1000 days of life have been well-studied. So, too, has the link between maternal health and low birth weight.3
However, the health and economic implications of maternal conditions (i.e. gestational diabetes mellitus [GDM]) that can cause fetal macrosomia (defined as a birth weight > 4,000 gms regardless of gestational age) have yet to be fully determined. GDM develops in women who are already at risk for developing insulin resistance because of obesity. Fetal macrosomia has been identified as a risk factor for the development of obesity in childhood, which in turn has been linked to the development of insulin resistance.4
What does poor diet cost us?
While the cost to society of poor diet choices has not been fully determined, it is generally agreed to be unacceptably high.
The total cost to the global economy of poor diet due to any cause is estimated at 5% of the global GDP, or roughly $3.5 trillion.5 Over- and undernutrition are at the core of this problem: 2013 figures from the WHO estimate the number of deaths due to obesity and overweight at over 2.8 million per year;6 conversely, malnutrition is currently blamed for over a third of child deaths.3
The costs of the long-term effects of GDM and fetal macrosomia are equally large. The budget impact of GDM for the US has been calculated at $1.8 billion annually. Obesity secondary to fetal macrosomia costs an extra $19,000 for lifetime medical costs; if applied to the population of obese 10-year olds in the US, this would equate to roughly $14 billion.4
The cost to society of poor diet goes beyond the monetary. The long-term effects of early undernutrition include reductions in intellectual ability, economic productivity and reproductive performance and the development of diabetes and cardiovascular disease. Studies have determined that intervention investments should be made within the first 1000 days of life if loss of functionality is to be avoided.7
Stunting, the most common form of undernutrition, affects 178 million children, mostly from Africa and Asia. Unaddressed, stunting becomes irreversible after the third year of life and can lead to restrictions in brain and muscle growth, adversely affecting mental capacity and future productivity.8
What can we do about poor diet choices?
Because nutrition is a major modifiable factor in the development of chronic diseases, it is generally thought that preventative measures would positively impact the burden of disease.
In a 2013 paper on the use of nutrition economics in public health, the authors identified three roles:
- Estimating the cost of poor nutrition and determining how important nutrition is to health and well-being;
- Defining which services to expand by comparing nutritional interventions against each other and against other non-nutritional modalities, and;
- Determining the best methods in changing nutritional behavior, including helping people make informed diet choices.9
In another paper, modeling of food patterns was proposed as a way to improve nutrition choices. Modeling will help identify foods that are affordable, nutrient-rich and culturally acceptable. But because data on the relationship between diet and SES are mostly derived from cross-sectional studies, they can be used to form hypotheses but do not prove causality.2
Improving nutrition on a population level revolves around an increased awareness among policy-makers on the benefits of good-quality diets in order to create strategies that can effectively address the negative impact of bad nutrition choices on the burden of disease. This may include public health promotion, food supplementation and changes to policy.2
Socioeconomic status continues to be a major influencer of diet choice. The cost to society of poor diet choices, whether resulting in over- or undernutrition, is already unacceptably high but continues to skyrocket. Its effects impact people from all countries and all walks of life, spans generations and sets the stage for a future pandemic. Combating this problem revolves around a better understanding that can only be acquired through more extensive study. Along with better understanding should come an improved awareness among authorities. Achievement of these goals can result in policy changes and the creation and implementation of preventative measures that may help to guarantee good nutrition choices on a population level.
- Darmon N, Drewnowski A. Does social class predict diet quality? Am J Clin Nutr. 2008;87:1107-1117.
- Darmon N, Drewnowski A. Contribution of food prices and diet cost to socioeconomic disparities in diet quality and health: A systematic review and analysis. Nutr Rev. 2015;73:643-660.
- Black RE, et al. Maternal and child undernutrition: global and regional exposures and health consequences. Lancet. 2008 Jan 19;371(9608):243-60.
- Lenoir-Wijnkoop I, van der Beek EM, Garssen J, Nuijten MJC, Uauy RD. Health economic modeling to assess short-term costs of maternal overweight, gestational diabetes, and related macrosomia – a pilot evaluation. Front Pharmacol. 2015;6:1-10.
- FAO. The State of Food and Agriculture (2013 Executive Summary). Food and Agricultural Organization, Rome; 2013.
- World Health Organization. Global Health Observatory (GHO) data. Available at http://www.who.int/gho/ncd/risk_factors/obesity_text/en/. Accessed 03 March 2016.
- Mizumoto K, Murakami G, Oshidari K, Trisnantoro L, Yoshike N. Health Economics of Nutrition Intervention in Asia : Cost of Malnutrition. J Nutr Sci Vtaminology. 2015;61:Suppl:S47-S49.
- WHO. WHO Child Growth Standards: Length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age: methods and development. World Health Organization, Geneva; 2006
- Lenoir-Wijnkoop I, Jones PJ, Uauy R, Segal L, Milner J. Nutrition economics – food as an ally of public health. Br J Nutr. 2013;109:777-784.