MacArthur SES & Health Network
MacArthur SES & Health Network


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SES and Diet

Summary prepared by Barbara Laraia. Last revised September, 2009.

Many chronic disease conditions that are strongly influenced by diet show health disparities by socioeconomic status.  These include cardiovascular disease, diabetes, obesity and certain types of cancer.  Disparities in these chronic diseases therefore beg the question as to whether dietary factors can explain these gaps.

In order to understand how dietary patterns may vary by socioeconomic status, it is first important to understand how these same patterns can change over time in society at large.   Dietary trends have shown clear and striking changes since the 1960s.  Total calorie consumption, percentage of energy from carbohydrates, grams of carbohydrates and grams of fat have steadily increased for both men and women between 1971 and 2000.  At the same time, the percentage of energy from fat, saturated fat and protein have decreased (CDC 2004, Putnam 2002) and the ratio of visible (e.g., butter, salad dressing, meat) to invisible fat (e.g., baked goods, cheese, fried foods) has decreased (Popkin 2001).  In addition, the percentage of adults eating out three or more times per week has increased significantly since 1987 to include almost 50% of men and 35% of women (Kant 2004).  With greater caloric intake overall, intake of a number of nutrients has actually improved (Popkin 2003, Kant 2007), while dietary intake of fruits and vegetables has remained fairly consistent since the 1960’s (Blanck 2008, Casagrande 2007). 

Popkin et al. (2003) found that there was a positive linear relationship between increasing diet quality and education, and that diet quality improved over time between 1965 and 1996.  However, the association between diet quality and income level was inconsistent.  Kant et al. (2007) studied a number of food and nutrient components at four time points between 1971 and 2002.  They found that although many indicators of diet improved over time, there was a persistent significant disparity by education and income.  For example, increased education was positively associated with a number of indicators of good nutrition, including a diet diversity score, fruit and vegetable intake, and vitamin C, vitamin A, calcium and potassium.  Income was also positively associated with reporting increase in total grams of food, calories, vitamin A and potassium intake, vegetable consumption and a decrease in energy density and grams of carbohydrates (Kant 2007).  Importantly, these disparities appeared to be consistent over time, neither widening nor narrowing between 1971 and 2002.  These data suggest that along with increases in calorie consumption, several dietary indicators have improved over time—but that disparities persist in dietary measures between income and education groups.  

Food cost and availability have been indicted in the diet quality differential by income and education.  In the US more affluent populations consume higher-quality diets than do disadvantaged populations (Drewnowski and Darmon 2005a).  Higher quality foods, with more nutrients per calorie, such as whole grains, lean meats, fish, low-fat dairy products, vegetables, and fruit cost more (Monsivais 2007).  In 2003, households in the highest 20% of  income spent on average $2,737 per person for food—equivalent to 6.6% of the total household income—whereas, households in the bottom 20% spent $1,769 per person for food—equivalent to 37.3% of total household income (Blisard 2007).  High food costs can thus be seen as representing an increased burden on families of low socioeconomic means.

When financial constraints become a barrier for poor and minority communities to access healthy foods, they are likely to consume fewer fruits and vegetables (Kendall 1996) and instead to consume lower quality and high energy dense foods (e.g., processed) that are high in starches, added sugars, and added fats (Drewnowski and Rolls 2005) (Drewnowski and Darmon 2005b).  Full service supermarkets and grocery stores are more abundant in affluent neighborhoods, allowing those with higher incomes to more easily access healthier food choices compared to households with lower-income in low-income neighborhoods (Gordon-Larsen 2006).  Supermarket accessibility and availability has also been associated with higher fruit and vegetable intake and more healthful diets (Morland 2002, 2006, Laraia 2004). Perceptions and beliefs about food accessibility and quality can also play an important role in diets.  The perceived barrier of food price and the perceived benefit of diet quality have both been found to be mediators in the association between socio-economic status and diet quality (Beydoun 2008).

The relationship between diet and socioeconomic status is dynamic.  With upwards of 2,000 new food products introduced each year, a constantly changing landscape of food venues, uneven access to nutritious foods and competing demands on a family’s food budget, unfavorable disparities in dietary intake are likely to continue.  Efforts to improve diet quality for high-risk groups remain an important focus at the individual, institutional and community level.


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REFERENCES

Beydoun MA, Wang Y. How do socio-economic status, perceived economic barriers and nutritional benefits affect quality of dietary intake among US adults? Eur J Clin Nutr 2008;62(3):303-13.

Blanck HM, Gillespie MS, Kimmons JE, Seymour JD, Serdula MK. Trends in fruit and vegetable consumption among US men and women, 1994-2005. Prev Chronic Disease. 2008;5(2):1-10.

Blisard N, Stewart H. Food spending by American households, 2003-04. ERS Summary Report. USDA, Economic Research Service. 2007.

Casagrande SS, Wang Y, Anderson C, Gary TL. Have Americans increased their fruit and vegetable intake? Am J Prev Med. 2007;32(4): 257-263.

Center for Disease Control and Prevention (CDC). Trends in intake of energy and macronutrients—United States, 1971-2000. Morbidity and Mortality Weekly Report (MMWR) 2004;53(04):80-82.

Drewnowski A, Darmon N. The economics of obesity: dietary energy density and energy cost. Am J Clin Nutr 2005a;82: 265S-273S.

Drewnowski A, Darmon N. Food choices and diet costs: an economic analysis. J Nutr 2005b;135(4):900-4.

Drewnowski A, Rolls BJ. How to modify the food environment. J Nutr 2005;135(4): 898-9.

Gordon-Larsen P, Nelson MC, et al. Inequality in the built environment underlies key health disparities in physical activity and obesity. Pediatrics 2006;117(2): 417-24.

Kant AK, Braubard BI. Eating on in America, 1987-2000: trends and nutritional correlates. Prev Med. 2004;38:243-249.

Kant AK, Graubard BI. Secular trends in the association of socio-economic position with self-reported dietary attributes and biomarkers in the US population: National Health and Nutrition Examination Survey (NHANES) 1971-1975 to NHANES 1999-2002. Public Health Nutr. 2007;10(2): 158-67.

Kendall A, Olson CM, et al. Relationship of hunger and food insecurity to food availability and consumption. J Am Diet Assoc 1996;96(10): 1019-24.

Laraia BA, Siega-Riz AM, Jones S, Kaufman JS. Proximity of supermarkets is positively associated with diet quality index for pregnancy. Prev Med 2004;39(5): 869-75.

Monsivais P, Drewnowski A. The rising cost of low-energy-density foods. J Am Diet Assoc 2007;107(12): 2071-6.

Morland K, Diez Roux AV, et al. Supermarkets, other food stores, and obesity: the atherosclerosis risk in communities study. Am J Prev Med 2006;30(4): 333-9.

Morland K, Wing S, et al. The contextual effect of the local food environment on residents' diets: the atherosclerosis risk in communities study. Am J Public Health 2002;92(11): 1761-7.

Popkin BM, Siega-Riz AM, Haines PS, Jahns L. Where’s the fat?  Trends in US Diets 1965-1996. Prev Med. 2001;32:245-254.

Popkin BM, Zizza C, et al. Who is leading the change?. U.S. dietary quality comparison between 1965 and 1996. Am J Prev Med 2003;25(1): 1-8.

Putnam J, Allshouse J, Kantar LS. U.S. Per Capita Food Supply Trends: More Calories, Refined Carbohydrates, and Fats. Food Review 2002;25(3): 2-15.


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Archive Essay:

Dietary Factors and SES

Summary prepared by Mary Fran Sowers in collaboration with the Allostatic Working Group; last revised in 1997.

An essay:

Dietary factors have been implicated as causes of chronic diseases because these factors are common, subtle and persistent overtime. It has been speculated that dietary factors may be a differentiating factor in the relatively greater disease burden among the social classes and the economically disadvantaged. There have been numerous relationships described between dietary factors and SES.

It has been assumed that because food costs disproportionately impact the total budget of the economically disadvantaged, they are less likely to be able to buy foods or to buy foods of appropriate quality. It is assumed that the educationally disadvantaged do not have the intellectual resources to select and appropriately prepare nutritionally-appropriate foods.

Secondly, it is well-recognized that groups of lower SES in affluent countries are more likely to be obese than those of higher SES. It is assumed that this obesity is a physical presentation of poor dietary and nutritional practices.

Indeed, it is a frequent observation that as populations evolve from a more agrarian society and/or less affluent society to either a more affluent and/or more urbanized position, there is an adoption of the dietary patterns of that more affluent (and usually more urbanized) society. Attendant to that adoption is a dramatic increase in obesity, greater longevity and manifestation of chronic diseases. Simultaneously, it is also noted that there is a tendency for the more affluent to alter their dietary patterns which tend to resemble a return to the carbohydrate-based diet of the more agrarian state, supplemented by access to fruits, vegetables and other modified foodstuffs which are too costly for the more impoverished.

It was noted in a recent publication by Popkin et al. (NEJM 335:716-720, 1996) that there appear to be convergence in the past 15 years of overall dietary quality between whites of higher SES and the black and whites of lower SES. Whether that convergence should be considered positive or not depends upon our view of the dietary quality of blacks and whites of lower SES. Studies conducted in the 1970's reported that diets of lower SES blacks and whites in the US was of higher quality than had previously been appreciated, albeit, they were not optimal. Furthermore, the diets of white higher SES residents of the US were actually inferior to those of the lower SES.

These observations should help sensitize us to the complexity of addressing and interpreting the relationship of dietary factors as a causal mechanism for the disease burden of those of lower social class. For example, in the US, the Poverty Index is determined by the cost of securing a mythical adequate diet. Thus, a measure of social class is defined by dietary factors including quality, quantity, and cost of foodstuffs. Methods to assess dietary factors (with the exception of the 24hour recall) are notoriously demanding from an educational perspective and are typically culturally-insensitive. Food frequency demands rapid decision-making (usually 400 decisions in less than 20 minutes) and in many instances are self-administered and require literacy. Food record keeping requires literacy and high motivation for record-keeping. Rarely do the assessments consider not only the issue of dietary quality but also the obvious relationship of energy input and energy outlay in physical activities of work and non-work time. Differences may separate on rural/urban lines as well as educational and economic lines. To factor in these elements means assessment of the impact of change in access to storage (refrigeration), the national food distribution system, to distance to food supplies and stores, and the common information sources (such as TV) that influence the food decision process.


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