Over-the-Counter Supplement Overuse: A Rare Potential Cause of Arsenic Poisoning and Bradycardia.

A 71-year-old woman with no significant past medical history presented with progressive cognitive decline, fatigue, and weight loss over two years. Her symptoms included bradycardia, anxiety, depression, and mild dyspnea on exertion. The patient followed a strict diet fortified with smoothies and an extensive regimen of 26 dietary supplements, consumed regularly over five years. Initial workup revealed sinus bradycardia at 40 beats per minute, mild cognitive impairment, and an elevated urine arsenic level (111.8 µg/L). After careful consideration of other possible etiologies, arsenic exposure was deemed a likely contributor to her symptoms. Arsenic poisoning, typically caused by contaminated water or food sources, can present with fatigue, cognitive issues, and cardiovascular abnormalities such as bradycardia. Algae-based supplements, including spirulina and chlorella, are particularly susceptible to arsenic contamination due to their ability to absorb metals from the environment. In this case, the patient's systemic symptoms were suggestive of arsenic toxicity, most likely secondary to dietary supplement use. This case highlights the importance of health care providers obtaining a thorough dietary and supplement history. When risk factors are identified based on history, selective screening for heavy metal toxicity is warranted. Enhanced regulation of supplements and population-level education about their potential dangers are imperative to prevent adverse outcomes related to supplement use.