"Side effects from increased magnesium intake are not common because the body removes excess amounts. Magnesium excess almost always occurs only when magnesium is supplemented as a medication. Lack of magnesium (deficiency) is rare. The symptoms include hyperexcitability, muscle,weakness, and sleepiness."

"An easy way to remember foods that are good magnesium sources is to think fiber. Foods that are high in fiber are generally high in magnesium. Dietary sources of magnesium include legumes, whole grains, vegetables (especially broccoli, squash, and green leafy vegetables), seeds, and nuts (especially almonds). Other sources include dairy products, meats, chocolate, and coffee. Water with a high mineral content, or hard  water, is also a source of magnesium. People take magnesium to prevent or treat magnesium deficiency. Magnesium deficiency is not uncommon in the US. It s particularly common among African Americans and the elderly."

"Because of the important interaction between phosphate and magnesium ions, magnesium ions are essential to the basic nucleic acid chemistry of life, and thus are essential to all cells of all known living organisms. Over 300 enzymes require the presence of magnesium ions for their catalytic action, including all enzymes utilizing or synthesizing ATP, or those that use other nucleotides to synthesize DNA and RNA. ATP exists in cells normally as a chelate of ATP and a magnesium ion."