Magnesium. Magnesium is required for the conversion of thiamine to its biologically active form. Furthermore, some thiamine-dependent enzymes also require magnesium. In patients who are deficient in both thiamine and magnesium, symptoms of thiamine deficiency may not respond to thiamine supplementation unless magnesium deficiency is also corrected. In addition, administration of large doses of thiamine can exacerbate magnesium deficiency
Magnesium supplementation should therefore be considered for patients being treated with thiamine.