Iodine apparently but I've never tried it myself. It works by a process called chelation. It's not harmful so probably worth a try but I would run it past her doctor first.
Chelation is the most common route either way, but the most successful routes really require heavy doctor monitoring due to the risks
Right I've seen home supplements for it (and infowars ads!) but to do it properly it should really be physician administered
https://www.webmd.com/balance/guide/what-is-chelation-therapy
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