Before you start these supplements, discuss their possible risks with your doctor to determine if you should take them, and for how long.
Both Chlorella and Spirulina May Contain Toxic Metals
“Some chlorella and spirulina supplements have been found to contain trace amounts of heavy metals like aluminum, mercury, nickel, and lead,” King says.
“The main health risks stem from contamination,” Abroon says. “Unregulated products may contain heavy metals, bacteria, or cyanotoxins that could be harmful if taken regularly.”
Contaminants can build up in your body and harm your kidneys, nervous system, and gastrointestinal tract, he adds. To avoid this, look for supplements that are third-party-tested.
Spirulina May Cause Liver Damage
“In practical terms, for most healthy adults, the risk of spirulina-related hepatotoxicity appears to be very low — it’s just not zero,” Abroon says. Plus, he notes that some findings suggest that certain algae supplements may support liver function (or at least not harm it in healthy people).
Spirulina May Produce Other Harmful Bacteria and Toxins
Repeated exposure to certain toxins in spirulina can strain the liver, limiting its ability to process toxins, says Abroon.