Magnesium occurs widely in foods and drinking water (except soft water). The highest amounts are in nuts, legumes and whole grains. Green vegetables are also good sources.

Magnesium in Foods

Food	Amount	Magnesium

All-bran cereal	8 oz. (1 cup)	318 mg
Soybean nuts, roasted	4 oz. (1/2 cup)	196 mg
Pumpkin seeds, roasted	1 oz.	152 mg
Tofu	4 oz. (1/2 cup)	127 mg
Navy beans, canned	8 oz. (1 cup)	122 mg
Lima beans, canned	8 oz. (1 cup)	94 mg
Almonds	1 oz.	86 mg
Cooked spinach	4 oz. (1/2 cup)	78 mg
Kidney beans, canned	8 oz. (1 cup)	74 mg
Lentils, cooked	8 oz.(1 cup)	71 mg
Bran flakes	8 oz.(1 cup)	70 mg
Potato with skin	1 medium potato	55 mg
Peanut butter	2 tbsp.	51 mg
Okra, boiled	4 oz. (1/2 cup)	46 mg
Peas, cooked or frozen	4 oz. (1/2 cup)	23 mg
Green beans, cooked or frozen	4 oz. (1/2 cup)	15 mg

One of the highest sources of magnesium is not a food at all; it is milk of magnesia taken as a laxative. Just two tablespoons provide 1,000 milligrams, which is more than twice as much as the Recommended Dietary Allowance (RDA) for anyone of any age. This is not necessarily a good thing; taken too frequently, it could be toxic. Milk of magnesia also decreases the availability of calcium and phosphorus.

How much do we need?

The RDA for magnesium is different for men and women, and different amounts are needed at different ages.

Gender	Age	Amount Required

Men	19-30	400 mg
Men	31-70	420 mg
Pregnant women	18 and under	400 mg
Pregnant women	19-30	350 mg
Pregnant women	31-50	360 mg
Women	19-30	310 mg
Women	31-70	320 mg

We usually absorb about half the magnesium we need from food; the presence of phytate and fiber reduce absorption to a minor extent.

If you eat about three servings of vegetables a day, have legumes two or three times a week, and get six to 10 servings of whole grains a day, it should be fairly easy to get enough magnesium from foods. However, the typical fast-food and refined diet of many Americans generally does not provide enough of this mineral.

In unusual medical circumstances, such as life-threatening convulsions or severe eclampsia of pregnancy, it may be necessary to provide supplementary magnesium by injection.

Is it safe?
Magnesium is safe in the appropriate amounts. However, as mentioned earlier, it can be toxic in excessive amounts. Milk of magnesia, which provides 1,000 milligrams of magnesium in just two tablespoons, is a commonly used, potentially toxic source. Elderly people who use it frequently as a laxative could be at risk for magnesia intoxication because their aging kidneys may not function well enough to clear it as well as a younger person's kidneys. Some of the signs of magnesium intoxication include:

drowsiness
lethargy
sweating
slurred speech

The upper limit for safe ingestion of magnesium from supplements and pharmacological sources is 350 milligrams a day. (This maximum does not include any of the magnesium obtained from food and water.)