Here are supplements that don't go together—or don't go with food. Magnesium and calcium. ... Iron and green tea. ... Vitamin C and B12. ... Fat-soluble and water-soluble vitamins. ... Vitamin D, vitamin K2, and other fat-soluble vitamins. ... Magnesium and vitamin D3. ... Copper and zinc. ... Omega-3s and vitamin E. More items... Oct 21, 2022