Chronic Kidney Disease and Access to Healthful Foods

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Individuals at high risk for the development of chronic kidney disease (CKD), or who already have the disease, are frequently encouraged by their health care providers to follow a “healthful” diet. Such a diet may be particularly difficult to follow if the recommended foods cannot be easily acquired—a situation that individuals living in poverty often face.

Poverty affects over 46 million (15 percent) Americans and has a disproportionate impact on racial and ethnic minorities (e.g., 35 percent of African Americans live in poverty), who also bear the greatest burden of advanced and progressive CKD (1, 2). Food insecurity (“limited or uncertain ability to acquire nutritionally adequate and safe foods in socially acceptable ways”) (3) often accompanies poverty. Affecting 17 million households in the United States (4), food insecurity is associated with several diet-related conditions—including diabetes and hypertension (5, 6)—and has recently been reported to be associated with CKD in the presence of either diabetes or hypertension (7).

Food-insecure individuals tend to follow dietary patterns characterized by decreased consumption of fruits, vegetables, and fiber, and increased intake of energy-dense foods, such as those rich in fat and sugar (8), which are often available at a lower price and may be more palatable than healthful foods (9). They also generally contain sodium-based food additives, which account for 75 percent of total sodium intake in the United States (10). Moreover, food-insecure individuals frequently reside in neighborhoods lacking the grocery stores most likely to sell healthful foods. Low-income neighborhoods often have few supermarkets and more fast-food and corner stores, whereas higher-income neighborhoods have many supermarkets with healthful food options (1113). The neighborhood food environment has been shown to have variable associations with health outcomes. Although some investigators report no association between obesity and density of fast-food stores in low-income neighborhoods (14), others have shown that changing the available food options in corner stores leads to better food choices, including an increase in fruit and vegetable consumption (15).

Several studies now document the association of healthful dietary patterns with better CKD outcomes. In addition to its favorable effects on blood pressure, adherence to the Dietary Approaches to Stop Hypertension (DASH) diet (16) has been associated with a lower risk of decline in estimated GFR (17). Furthermore, adherence to a Mediterranean dietary pattern has been associated with better kidney function among older men and with better survival among individuals with CKD (18). The alkali-inducing fruits and vegetables that are the mainstays of these diets may improve metabolic acidosis and attenuate kidney injury (19, 20).

Although large-scale clinical trials are certainly needed to test the hypothesis that these healthful dietary patterns improve CKD outcomes independently of other lifestyle factors, we likely already have enough data to warrant recommending such diets in the clinical setting. Thus, an assessment of potential barriers or competing priorities to following these dietary recommendations is essential. A simple screening question regarding food insecurity (e.g., “Have you had to skip meals because there wasn’t enough money?”) could allow the identification of patients at increased risk of poor outcomes and guide dietary recommendations that take into account potential barriers to accessing healthful foods. Longitudinal studies in this area are needed to fully elucidate the role of dietary access in CKD outcomes.

Notes

[1] Deidra C. Crews, MD, ScM, FASN, is affiliated with the Johns Hopkins University School of Medicine in Baltimore, MD.

References

1.DeNavas-Walt C, et al. U.S. Census Bureau, Current Population Reports, P60–243, Income, Poverty, And Health Insurance Coverage in the United States: 2011. Washington, DC: U.S. Government Printing Office, 2012.

2. US Renal Data System. USRDS 2012 Annual Data Report: Atlas of End-Stage Renal Disease in the United States. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Disease, 2012.

3. Anderson SA. Core indicators of nutritional state for difficult-to-sample populations. J Nutrition 1990; 120:1559–1599.

4. Coleman-Jensen A, et al. Household Food Security in the United States in 2010. ERR-125, U.S. Dept. of Agriculture, Econ. Res. Serv. September 2011. (http://www.ers.usda.gov/Publications/err125/).

5. Castillo DC, et al. Inconsistent access to food and cardiometabolic disease: the effect of food insecurity. Curr Cardiovasc Risk Rep 2012; 6:245–250.

6. Seligman HK, et al. Food insecurity is associated with chronic disease among low-income NHANES participants. J Nutrition 2010; 140:304–310.

7. Crews DC, et al. for the Centers for Disease Control and Prevention Chronic Kidney Disease Surveillance Team. Effect of food insecurity on chronic kidney disease in lower-income Americans. Am J Nephrol 2014; 39:27–35.

8. Popkin BM. Contemporary nutritional transition: determinants of diet and its impact on body composition. Proc Nutr Soc 2011; 70:82–91.

9. Offer A, et al. Obesity under affluence varies by welfare regimes: the effect of fast food, insecurity, and inequality. Econ Hum Biol 2010; 8:297–308.

10. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th Edition. Washington, DC: U.S. Government Printing Office, 2010.

11.Lovasi GS, et al. Built environments and obesity in disadvantaged populations. Epidemiol Rev 2009; 31:7–20.

12. Zenk SN, et al. Fruit and vegetable access differs by community racial composition and socioeconomic position in Detroit, Michigan. Ethn Dis 2006; 16:275–280.

13. Morland K, Filomena S. Disparities in the availability of fruits and vegetables between racially segregated urban neighbourhoods. Public Health Nutr 2007; 10:1481–1489.

14. Richardson AS, et al. Neighborhood fast food restaurants and fast food consumption: a national study. BMC Public Health 2011; 11:543.

15. Gittelsohn J, et al. An urban food store intervention positively affects food-related psychosocial variables and food behaviors. Health Educ Behav 2010; 37:390–402.

16. Appel LJ, et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med 1997; 336:1117–1124.

17. Lin J, et al. Association of dietary patterns with albuminuria and kidney function decline in older white women: a subgroup analysis from the Nurses’ Health Study. Am J Kidney Dis 2011; 57:245–254.

18. Huang X, et al. Mediterranean diet, kidney function, and mortality in men with CKD. Clin J Am Soc Nephrol 2013; 8:1548–1555.

19. Goraya N, et al. Dietary acid reduction with fruits and vegetables or bicarbonate attenuates kidney injury in patients with a moderately reduced glomerular filtration rate due to hypertensive nephropathy. Kidney Int 2012; 81:86–93.

20. Goraya N, et al. A comparison of treating metabolic acidosis in CKD stage 4 hypertensive kidney disease with fruits and vegetables or sodium bicarbonate. Clin J Am Soc Nephrol 2013; 8:371–381.


May 2014 (Vol. 6, Number 5)