Leafy green vegetables, nuts, fish, seeds and dark chocolate are good food sources of magnesium. These sources have at least 20 milligrams of magnesium per serving, or at least 5 percent of the average recommended daily value.
One ounce of dry roasted almonds has 80 mg of magnesium, making almonds one of the foods highest in magnesium, while a 1/2 cup of boiled spinach is a close second with 78 mg. Cashews, peanut butter and peanuts are other nut options with a high content, and broccoli, carrots, kale and chard are some vegetables that can serve as good supplemental foods. Halibut and salmon are two types of fish that are particularly high.
Dedicated magnesium supplements come in a few different forms, and varieties that can dissolve entirely in water provide the best absorption rate. Magnesium is also found in some medicines, such as laxatives. Zinc can negatively affect magnesium absorption, so a diet high in zinc may affect magnesium levels or contribute to a deficiency.
Magnesium deficiency can result in nausea, vomiting, numbness, seizures and hypocalcemia, depending on how severe the deficiency is and how long the person has been deficient. The elderly, alcoholics, type two diabetics and those with Crohn's disease are at a higher risk of magnesium deficiency.