Vankawala and colleagues at the Ronald Reagan UCLA Medical Center reported a single case in which a 71-year-old woman consuming 26 daily dietary supplements over five years, including spirulina and chlorella as algae-based products, developed urine arsenic of 111.8 µg/L (reference range 0 to 34.9 µg/L), sinus bradycardia at 40 beats per minute, leukopenia, and a Montreal Cognitive Assessment score of 18 out of 30 indicating mild-to-moderate cognitive impairment. Arsenic was the most plausible contributor to the cardiovascular and neurological presentation after other etiologies were excluded. The supplements themselves were not tested for arsenic, and direct attribution to any specific product concentration is not possible from this report.
Key numbers
Biomarker findings (Table 2):
- Urine arsenic: 111.8 µg/L (laboratory reference range 0 to 34.9 µg/L; approximately 3.2 times the upper reference limit)
- Urine arsenic-to-creatinine ratio: 116.5 µg/g creatinine (reference range 0 to 29.9 µg/g; approximately 3.9 times the upper reference limit)
- Urinary lead and mercury: within normal reference ranges (values not printed)
- Leukocyte count: 2,660 cells/µL (reference 4,500 to 11,000)
- Thyroid-stimulating hormone: 2.9 µIU/mL (within range); electrolytes, creatinine, calcium, vitamin B12, B1, D all within normal or elevated normal ranges; HIV and RPR nonreactive
Cardiac findings: Sinus bradycardia at 40 beats per minute on admission, coincident with initiation of supplement regimen in 2019. Heart rate appropriate variability with ambulation (40 to 80 beats per minute). No pauses or heart block. Pacemaker not indicated. Trace pericardial effusion on point-of-care ultrasound; normal ejection fraction.
Cognitive finding: Montreal Cognitive Assessment 18/30 (mild-to-moderate impairment). Normal brain CT (no atrophy or acute process).
Supplement risk stratification (Table 1, adapted from Reference 3 cited by the authors):
- High risk (algae-based): spirulina, chlorella
- Moderate risk (herbal): turmeric, yerba mate, ginkgo biloba, astragalus root, olive leaf extract, black seed oil, bee pollen
- Low risk (synthetic or purified): vitamin D3, vitamin C, omega-3 fish oil, zinc, magnesium, B-complex, vitamin B12, vitamin K2, CoQ10, D-ribose, resveratrol, acetyl-L-carnitine with folic acid, coconut oil, Alive! multivitamin, kimchi probiotics, powdered greens (moringa, maca, cacao powder)
The risk stratification was derived by the authors from an external reference (Hedegaard et al. 2013, cited as Reference 3 in the case report) and was not generated from direct testing of the patient’s supplements. The patient’s supplements were never tested for heavy metals.
Management: Chelation therapy not recommended (urine arsenic below the acute-exposure threshold of greater than 1,000 µg/L cited by the authors). Patient discharged with advice to discontinue all supplements; patient resumed supplements at her husband’s insistence. At 3-month follow-up, continued worsening of weight loss and cognitive function.
Methods (brief)
Case report. Urine arsenic measured as part of a 24-hour urine heavy metal screen ordered during inpatient evaluation. Laboratory testing included serum electrolytes, creatinine, TSH, B12, B1, vitamin D, complete blood count, HIV serology, RPR, and urine arsenic. Brain CT and cardiac point-of-care ultrasound were performed. Montreal Cognitive Assessment administered. Toxicology consulted. No analytical testing of supplements was performed. LOD/LOQ, CRM, and recovery data for the urine arsenic assay are not reported in the case report.
Evidence fitness
Supports:
- Clinical documentation that prolonged consumption of algae-based supplements can produce urine arsenic biomarker levels exceeding the upper reference range
- Identification of spirulina and chlorella as algae-based supplements associated with elevated arsenic exposure in published literature (via the authors’ citation of Hedegaard et al. 2013)
- Context for the clinical presentation of chronic arsenic toxicity (bradycardia, cognitive decline, leukopenia, weight loss) in a supplement-consuming population
- Discussion of the arsenic-bradycardia mechanism: arsenic damages myocardium, inhibits mitochondrial enzymes, causes electrolyte imbalances, and increases parasympathetic tone
Does not support:
- Supplement-specific arsenic concentration measurements (supplements were not tested)
- Population-level frequency estimates of arsenic toxicity from supplement use
- Attribution of arsenic to any single supplement in the patient’s 26-supplement regimen
- Generalizable exposure estimates; this is n=1
Limitations
The supplements were not analytically tested for arsenic or other metals, so the source of arsenic exposure cannot be confirmed. Attribution to spirulina or chlorella rests on published literature cited by the authors, not on direct measurement of this patient’s products. The patient’s partial non-compliance with discharge advice (resuming supplements) limited post-cessation monitoring. The patient’s advanced age introduces the possibility that intrinsic age-related cardiac and cognitive changes contributed to the presentation independently of arsenic. The case report does not distinguish inorganic from organic arsenic speciation in the urine result.
Related evidence
- Ingredient class — greens/superfood blends (Pb/cadmium (Cd)/inorganic arsenic (iAs) hyperaccumulator)
- Ingredient class — algae/seaweed-based
- Dietary Supplements
- Arsenic
- Spirulina and Chlorella Dietary Supplements—Are They a Source Solely of Valuable Nutrients?
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