A case of severe nephrotoxicity associated with long-term dietary supplement use

Dietary supplements are widely used for their perceived health benefits without side effects and hence have minimal regulation. However, they have been associated with various toxicities including kidney disease. We report a 65-year-old male who had very heavy daily intake of dietary supplements for 3 years. He presented with acute kidney injury and nephrotic-range proteinuria. The renal biopsy showed acute tubular necrosis with vacuolization, acute interstitial nephritis, and secondary membranous nephropathy, consistent with an non-steroidal anti-inflammatory drug (NSAID)-like nephropathy. This was postulated to be related to the cyclooxygenase (COX) inhibitors (anthocyanins) in cherry extract that was a significant part of the patient’s dietary supplement use. His proteinuria completely resolved and serum creatinine stabilized after discontinuation of all dietary supplements and a prolonged (5 months) course of prednisone. Clinicians are advised to specifically inquire about dietary supplements, especially cherry extract, as a potential cause of new-onset renal failure and proteinuria.