Americans' use of dietary supplements that are potentially harmful in CKD

Background: The prevalence in the United States of dietary supplement use that may be harmful to those with chronic kidney disease (CKD) is unknown. We sought to characterize potentially harmful supplement use by individual CKD status.

Study design: Cross-sectional national survey (National Health and Nutrition Examination Survey, 1999-2008).

Setting & participants: Community-based survey of 21,169 nonpregnant noninstitutionalized US civilian adults (aged ≥20 years).

Predictor: CKD status (no CKD, at risk of CKD [presence of diabetes, hypertension, and/or cardiovascular disease], stages 1/2 [albuminuria only (albumin-creatinine ratio ≥30 mg/g)], or stages 3/4 [estimated glomerular filtration rate of 15-59 mL/min/1.73 m(2)]).

Outcome: Self-reported use of dietary supplements containing any of 37 herbs the National Kidney Foundation identified as potentially harmful in the setting of CKD.

Measurements: Albuminuria and estimated glomerular filtration rate assessed from urine and blood samples; demographics and comorbid conditions assessed by standardized questionnaire.

Results: An estimated 8.0% of US adults reported potentially harmful supplement use within the last 30 days. A lower crude estimated prevalence of potentially harmful supplement use was associated with higher CKD severity (no CKD, 8.5%; at risk, 8.0%; stages 1/2, 6.1%; and stages 3/4, 6.2%; P < 0.001). However, after adjustment for confounders, those with or at risk of CKD were as likely to use a potentially harmful supplement as those without CKD: at-risk OR, 0.93 (95% CI, 0.79-1.09); stages 1/2 OR, 0.83 (95% CI, 0.64-1.08); and stages 3/4 OR, 0.87 (95% CI, 0.63-1.18); all versus no CKD.

Limitations: Herb content was not available and the list of potentially harmful supplements examined is unlikely to be exhaustive.

Conclusions: The use of dietary supplements potentially harmful to people with CKD is common regardless of CKD status. Health care providers should discuss the use and potential risks of supplements with patients with and at risk of CKD.