Magnesium is ingested through foods like beans, broccoli, nuts and seeds. It benefits humans by acting as a laxative and helping prepare the bowel for surgery. A lack of magnesium can cause dizziness, vomiting and weakness due to impacts on bone strength. Fluorine provides no benefits and is toxic, though fluoride in small amounts can strengthen teeth. Too much fluoride or fluorine can negatively impact brain function. Magnesium and fluorine do not interact in the body, but can form an ionic bond when combined.