The U.S. RDA for magnesium is the amount of the mineral used as a standard in nutrition labeling of foods. This allowance is based on the 1968 Recommended Dietary Allowances (RDA) for 24 sex-age categories set by the Food and Nutrition Board of the National Academy of Sciences. The 1989 RDA has been set at 280 milligrams per day for women 19 to 50 years of age and 350 milligrams for men 19 to 50 years of age.
As you can see, in 1985 and 1986, about 25 percent of the magnesium in diets of women was supplied by grain products and another 25 percent by fruits and vegetables. Meat, poultry, and fish provided about 18 percent of the magnesium. Fats, sweets, and beverages supply 14 percent of the magnesium; however, they are not considered in our list of "good sources" because they are high in calories compared to the amounts of vitamins and minerals they provide. Foods that contain small amounts of magnesium but are not considered good sources can contribute significant amounts of magnesium to an individual's diet if these foods are eaten often or in large amounts.
WHY DO WE NEED MAGNESIUM?
Magnesium, a mineral, is used in building bones, manufacturing proteins, releasing energy from muscle storage, and regulating body temperature.
DO WE GET ENOUGH MAGNESIUM?
According to recent USDA surveys, the average intake of magnesium by women 19 to 50 years of age was about 74 percent of the RDA. Men of the same age got about 94 percent of the recommended amount. About 50 percent of women had intakes below 70 percent of their RDA.
HOW CAN WE GET ENOUGH MAGNESIUM?
Eating a variety of foods that contain magnesium is the best way to get an adequate amount. Healthy individuals who eat a balanced diet rarely need supplements. Intakes of magnesium tend to be low in relation to recommendations, and there aren't that many foods that are really good sources; thus, it may take special care to ensure an adequate intake. The list of foods will help you select those that are good sources of magnesium as you follow the Dietary Guidelines. The list of good sources was derived from the same nutritive value of foods tables used to analyze information for recent food consumption surveys of the U.S. Department of Agriculture, Human Nutrition Information Service.
HOW TO PREPARE FOODS TO RETAIN MAGNESIUM
Magnesium is lost in cooking some foods even under the best conditions. To retain magnesium:
WHAT ABOUT WHOLE-GRAIN CEREALS?
Whole-grain ready-to-eat cereals usually contain 10 percent of the U.S. RDA for magnesium. Since cereals vary, check the label on the package for the percentage of the U.S. RDA for a specific cereal.
WHAT IS A SERVING?
The serving sizes used on the list of good sources are only estimates of the amounts of food you might eat. The amount of nutrient in a serving depends on the weight of the serving. For example, 1/2 cup of a cooked vegetable contains more magnesium than 1/2 cup of the same vegetable served raw, because a serving of the cooked vegetable weighs more. Therefore, the cooked vegetable may appear on the list while the raw form does not. The raw vegetable provides the nutrient - but just not enough in a 1/2-cup serving to be considered a good source.
WHAT ARE GOOD SOURCES OF MAGNESIUM?
FOOD SELECTED PERCENTAGE OF SERVING SIZE U.S. RDA (1)
BREADS, CEREALS, AND OTHER GRAIN PRODUCTS
Bread, whole-wheat 2 slices +
Artichoke, globe (french),
cooked 1 medium +
MEAT, POULTRY, FISH, AND ALTERNATES
Fish and Seafood
Nuts and Seeds
MILK, CHEESE, AND YOGURT
Milk, chocolate, made with
skim milk 1 cup +
(1) A selected serving size contains -
+ 10-24 percent of the U.S. RDA for adults and children over 4 years of age
++ 25-39 percent of the U.S. RDA for adults and children over 4 years of age
+++ 40 percent or more of the U.S. RDA for adults and children over 4 years of age
(2) See section on whole-grain cereals.
(3) If made with magnesium chloride or nigari (a coagulant derived from seawater).