Do you know if your patient is taking a dietary supplement? Do you know the definition of a dietary supplement? What dietary supplements are safe and what supplements are potentially harmful in the chronic kidney disease population? Do you include dietary supplements when counseling your CKD patients on potentially harmful over the counter products to avoid?
The U.S. Food and Drug Administration defines a dietary supplement as a product taken by mouth that is intended to supplement the diet and that contains one or more “dietary ingredients.” Dietary ingredients include vitamin and mineral products, “botanical” or herbal products, amino acid products and enzyme supplements. 1 Dietary supplements can be divided into two basic groups: vitamin-mineral supplements and non-vitamin, non-mineral supplements, frequently called natural or herbal supplements (see Tables 1 and 2).
Dietary supplements are regulated like foods. Unlike new drugs, they do not have to go through FDA review for safety and effectiveness or be “approved.” Manufacturers are responsible for meeting certain requirements established by the Dietary Supplement Health and Education Act of 1994, but the FDA only evaluates the safety of supplements after the products are on the shelf through research and the FDA’s MedWatch program for adverse event reporting. 2
Many people think that since herbal supplements are “natural” there is no harm in using these products. With TV, radio, and print advertisements, the Internet, and family and friends making claims and providing personal testimony, it is no surprise that about half the U.S. population uses dietary supplements.
Members of the Centers for Disease Control and Prevention CKD Surveillance Team recently published a paper in the American Journal of Kidney Disease describing their findings on the use of dietary supplements in persons with and at risk of CKD. 4 They were especially interested in the use of dietary supplements containing any of the 37 herbs identified as potentially harmful in CKD on the National Kidney Foundation website. (see tables 3, 4, 5) The community-based survey of more than 21,000 adults included questions on the use of any dietary supplements in the past month, a physical exam and blood and urine collection. The groups were divided into “no CKD” (46.3% of total), “at risk of CKD” (39.0% of total), “CKD stages 1/2” (8% of total), and “CKD Stages 3/4” (6% of total). People with very low GFRs (<15ml/min) were excluded. After adjustment for confounders, those with or at risk of CKD were as likely to use a potentially harmful supplement as those without CKD.
There are multiple papers in the literature on interactions between herbal medicines and prescription drugs with examples of supplements increasing or decreasing the effect of the prescription medications. The FDA Dietary Supplement Alerts website lists adverse events from discoloration of skin to hepatic and renal toxicity related to herbal supplements, and a review by Bagnis et al. cites multiple examples of nephrotoxicity related to herbal medicine, resulting in everything from hyperkalemia and kidney stones to acute tubular necrosis and urinary tract carcinoma. 6
A survey conducted by the Harvard Opinion Research Program at the Harvard School of Public Health in 2011 asked users why they made the decision to use dietary supplements. 7 The most common answers were “to feel better” (41%), “to improve overall energy levels” (40.8%), and “to boost your immune system” (35.9%). While it is not known exactly why CKD patients choose to use dietary supplements, it is easy to imagine they would agree with the answers to the Harvard survey.
With the widespread use of dietary supplements and the potential harm they can cause in CKD, it is important to include questions and advice about supplement use with each patient encounter. Use the following websites to keep you and your patients informed about safety, risks and benefits of all types of dietary supplements.
National Center for Complementary and Alternative Medicine (NCCAM): http://nccam.nih.gov/
Office of Dietary Supplements (ODS): http://ods.od.nih.gov/
Food and Drug Administration (FDA): www.fda.gov/
Center for Food Safety and Applied Nutrition (CFSAN): www.fda.gov/aboutfda/centersoffices/cfsan/default.htm
Natural Medicines Comprehensive Database: http://naturaldatabase.therapeuticresearch.com/
FDA Medwatch: www.fda.gov/Safety/MedWatch/default.htm
National Kidney Foundation: www.kidney.org/atoz/content/herbalsupp.cfm
1. U.S. Food and Drug Administration www.fda.gov/aboutFDA/transparency/basics/ucm194357.html Accessed May 2, 2013.
2. Final rule promotes safe use of dietary supplements www.fda.gov/consumer/updates/dietarysupps062207.html Accessed April 16, 2013
3. Zelig, R., Radler, D.R. (2012). Understanding the properties of common dietary supplements: clinical implications for healthcare practitioners. Nutr Clin Pract 27(6): 767 – 776.
4. Grubbs, V. et al (2013). Americans’ use of dietary supplements that are potentially harmful in CKD. Am J Kidney Dis. 61(5): 739 – 747.
5. Use of herbal supplements in chronic kidney disease
www.kidney.org/atoz/content/herbalsupp.cfm Accessed April 15, 2013
6. Bagnis, C. I., et al (2004) Herbs and the kidney. Am J Kidney Dis 44(1): 1 – 11.
7. Blendon, R. J., et al (2013) Users’ views of dietary supplements. JAMA Intern Med 173(1): 74 – 76.