Easy now guys, CC is right: there are currently five forms of "ferric" product available in the world. Allow me to provide my "understanding of basic nutrients" regarding each of them.
Ferric gluconate is an IV-only formulation that is given to patients receiving hemodialysis or patients with chemo-induced anemia. CC is right, you should not take a multivitamin that says it contains ferric gluconate because it does not exist in oral form.
Ferric subsulfate is a topical liquid. It is used to stop bleeding following cervical biopsy. CC is right, you should not take a multivitamin that contains ferric subsulfate. If your cervix is bleeding, I suggest the emergency department.
Ferric hexacyanoferrate is a capsule! Wow, you can take it by mouth! We're getting closer to the multivitamin possibility now. I am hopeful that your multivitamin does not contain ferric hexacyanoferrate, because it is only used as an antidote for radioactive cesium or thallium ingestion. You will know if your multivitamin contains this form of iron if your feces turns blue. This is an expected side effect.
Ferric citrate is also available in an oral dosage form. The Livestrong article is right on point when it says, "there is a reduced chance of iron poisoning with iron citrate." That's because it is not absorbed and is not used as an iron supplement. It is only available with a prescription and is used to treat hyperphosphatemia. It binds phosphate in the GI tract and is excreted in the feces.
Ferric carboxymaltose is the last available ferric product. It is used to treat iron-deficiency anemia. CC is right; do not buy a multivitamin that contains this product., because it is only available as a vial for IV-injection.
TLDR: thank you CC for providing me a link to the Livestrong article. If your multivitamin contains a ferric form of iron, please call the FDA, as the supplement company is in violation of federal law (either the Pure Food and Drug Act of 1906 or the Durham-Humphrey Amendment of 1951).
