Kidney Disease in Urban Poor Linked to Bad Eating Habits

People least adherent to a DASH-style diet had a 3-fold increased odds of chronic kidney disease compared with those who were most adherent.
People least adherent to a DASH-style diet had a 3-fold increased odds of chronic kidney disease compared with those who were most adherent.

Poor dietary habits are associated with an increased risk of chronic kidney disease (CKD) among poverty-stricken urban residents, according to a new study.

Based on the finding, researchers concluded that dietary habits “may represent a target for interventions aimed at reducing disparities in CKD.”

The study included 2,058 community-dwelling adults aged 30–64 years (mean 48 years) living in Baltimore classified into poverty and nonpoverty groups. Researchers led by Deidre C. Crews, MD, ScM, of Johns Hopkins University School of Medicine in Baltimore, evaluated subjects' adherence to the Dietary Approaches to Stop Hypertension (DASH) diet, which is high in fruits and vegetables, moderate in low-fat dairy products, and low in animal protein, but with substantial amounts of plant protein from legumes and nuts.

The researchers calculated a DASH diet adherence score for each participant based on 9 nutrient targets: protein, total fat, saturated fat, cholesterol, fiber, magnesium, calcium, potassium, and sodium. Subjects who met the DASH target for a nutrient received a score of 1, and participants who achieved an intermediate target for a nutrient received a score of 0.5. The highest achievable total score was 9.

Compared with the highest DASH score tertile (2.5–8), the lowest tertile (0–1) was associated with 3-fold greater adjusted odds of CKD in the poverty group, but was not associated with CKD in the nonpoverty group, Dr. Crews' team reported in the Journal of Renal Nutrition (2015;25:103-110).

“To our knowledge, this is the first report comparing dietary patterns in the context of socioeconomic disparities in CKD,” Dr. Crews and her colleagues wrote. “In our study, participants living in poverty consumed diets lower in several potentially renal-protective nutrients than consumed by the nonpoverty participants, including potassium.”

Of the 2,058 participants, 42% fell into the poverty group, which included individuals whose self-reported household income was less than 125% of the 2004 Department of Health and Human Services poverty guideline (family of 4 earning less than $23,562 annually). The non-poverty group included individuals with higher self-reported household income. The investigators defined CKD as an estimated glomerular filtration rate below 60 mL/min/1.73 m2.

The median DASH score for the study population was 1.5. Only 4.5% of the poverty group and 6.1% of the nonpoverty group had dietary patterns consistent with the DASH diet, according to the investigators. The poverty group had significantly higher cholesterol and lower fiber, magnesium, calcium, and potassium intake than the nonpoverty group, but the 2 groups had similar intake of saturated fat and sodium.

In a discussion of study limitations, the authors noted that, because of the study's cross-sectional design, a direct causal relationship between DASH diet adherence and CKD cannot be inferred and reverse causality (for example, a CKD diagnosis affecting adherence to a DASH-style diet) is possible.

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