Calcium and magnesium stored in the bones serve as a mineral reservoir for the blood. When needed, the body withdraws these minerals from the bone to circulate in the blood. Consume an appropriate amount daily to maintain health. The Recommended Dietary Allowance, RDA, for magnesium is 240 to 420 mg per day, while the Adequate Intake, AI, for calcium is estimated at 1,000 to 1,300 mg per day.
Dairy Products
Calcium and magnesium occur abundantly in milk and milk products. Persons who prefer not to drink milk may choose to eat cheese or yogurt. Powdered nonfat milk may be added to casseroles or soups during preparation. Some people with lactose intolerance may be able to consume small quantities of milk or may choose non-dairy sources of calcium, including some brands of soy milk, tofu or corn tortillas and calcium-fortified juices.
Nuts, Seeds and Legumes
Some nuts, such as almonds, and some seeds, such as sesame, can provide calcium for people who do not use milk products. Nuts and legumes also provide significant sources of magnesium. The best sources of magnesium per calorie include spinach, broccoli, corn, green beans, tomato juice, navy beans, pinto beans, tofu, halibut, cashews, artichokes and black-eyed peas.
Vegetables
Vegetables such as mustard greens, turnip greens, bok choy, kale, parsley, broccoli, watercress and the seaweeds used in Japanese cooking are good sources of easily-absorbed calcium. Some dark green, leafy vegetables, such as spinach and Swiss chard, are calcium-rich, but this calcium is not easily absorbed because of the binders such as oxalates and phytates that chemically combine with calcium to form complexes.
For instance, it would take 8 cups of spinach, which actually contains six times as much calcium as 1 cup of milk, to deliver the same amount of calcium that can be absorbed. Dark green vegetables provide a significant source of magnesium.
Whole Grains
Whole grains provide a solid source of magnesium. Magnesium is lost during refining of wheat flour and rice and in the processing of foods such as sugar. It is not added back as part of the enrichment of cereals.
A slice of most breads contains only 5 percent to 10 percent of the calcium in a serving of milk, but can provide a major source for people who eat the equivalent of several slices of bread, because this calcium is well-absorbed, according to Eleanor Whitney and Sharon Rolfes in "Understanding Nutrition."
References
- "Understanding Nutrition, Ninth Edition"; Eleanor Noss Whitney and Sharon Rady Rolfes; 2002
- "Krause's Food, Nutrition, & Diet Therapy, 10th Edition"; L. Kathleen Mahan and Sylvia Escott-Stump; 2000
- USDA: MyPyramid.gov: Inside the Pyramid: Health Benefits and Nutrients
- USDA: MyPyramid.gov: Inside the Pyramid: Why is it important to eat grains, especially whole grains?
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