http://en.wikipedia.org/wiki/Calcium
Calcium, the most abundant mineral in the body, is found in some foods, added to others, available as a dietary supplement, and present in some medicines (such as antacids). Calcium is required for muscle contraction, blood vessel expansion and contraction, secretion of hormones and enzymes, and transmitting impulses throughout the nervous system.
The body strives to maintain constant concentrations of calcium in blood, muscle, and intercellular fluids, though less than <1% of total body calcium is needed to support these functions.
The remaining 99% of the body's calcium supply is stored in the bones and teeth where it supports their structure.
Bone itself undergoes continuous remodeling, with constant resorption and deposition of calcium into new bone.
The balance between bone resorption and deposition changes with age. Bone formation exceeds resorption in growing children, whereas in early and middle adulthood both processes are relatively equal. In aging adults, particularly among postmenopausal women, bone breakdown exceeds formation, resulting in bone loss that increases the risk of osteoporosis over time .
Food
Milk, yogurt, and cheese are rich sources of calcium and are the major food contributors of this nutrient to people in the United States.
Nondairy sources include vegetables, such as Chinese cabbage, kale, and broccoli.
Most grains do not have high amounts of calcium unless they are fortified; however, they contribute calcium to the diet because they do have small amounts and people consume them frequently.
Foods fortified with calcium include many fruit juices and drinks, tofu, and cereals.
Food Milligrams (mg) per serving Percent DV*
Yogurt, plain, low fat, 8 ounces 415 42
Sardines, canned in oil, with bones, 3 ounces 324 32
Cheddar cheese, 1.5 ounces 306 31
Milk, nonfat, 8 ounces 302 30
Milk, reduced-fat (2% milk fat), 8 ounces 297 30
Milk, lactose-reduced, 8 ounces** 285-302 29-30
Milk, whole (3.25% milk fat), 8 ounces 291 29
Milk, buttermilk, 8 ounces 285 29
Mozzarella, part skim, 1.5 ounces 275 28
Yogurt, fruit, low fat, 8 ounces 245-384 25-38
Orange juice, calcium-fortified, 6 ounces 200-260 20-26
Tofu, firm, made with calcium sulfate, ½ cup*** 204 20
Salmon, pink, canned, solids with bone, 3 ounces 181 18
Pudding, chocolate, instant, made with 2% milk, ½ cup 153 15
Cottage cheese, 1% milk fat, 1 cup unpacked 138 14
Tofu, soft, made with calcium sulfate, ½ cup*** 138 14
Spinach, cooked, ½ cup 120 12
Ready-to-eat cereal, calcium-fortified, 1 cup 100-1,000 10-100
Instant breakfast drink, various flavors and brands, powder prepared with water, 8 ounces 105-250 10-25
Frozen yogurt, vanilla, soft serve, ½ cup 103 10
Turnip greens, boiled, ½ cup 99 10
Kale, cooked, 1 cup 94 9
Kale, raw, 1 cup 90 9
Ice cream, vanilla, ½ cup 85 8.5
Soy beverage, calcium-fortified, 8 ounces 80-500 8-50
Chinese cabbage, raw, 1 cup 74 7
Tortilla, corn, ready-to-bake/fry, 1 medium 42 4
Tortilla, flour, ready-to-bake/fry, one 6" diameter 37 4
Sour cream, reduced fat, cultured, 2 tablespoons 32 3
Bread, white, 1 ounce 31 3
Broccoli, raw, ½ cup 21 2
Bread, whole-wheat, 1 slice 20 2
Cheese, cream, regular, 1 tablespoon 12 1
** Calcium content varies slightly by fat content; the more fat, the less calcium the food contains.
*** Calcium content is for tofu processed with a calcium salt. Tofu processed with other salts does not provide significant amounts of calcium.
It is recommended to eat 3 cups of foods from the milk group per day.
A cup is equal to 1 cup (8 ounces) of milk.
1 cup of yogurt.
1.5 ounces of natural cheese (such as Cheddar), or 2 ounces of processed cheese (such as American).
A healthy diet as one that:
• Emphasizes a variety of fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products:
Many dairy products, such as milk, cheese, and yogurt, are rich sources of calcium. Some vegetables provide significant amounts of calcium, as do some fortified cereals and juices.
• Includes lean meats, poultry, fish, beans, eggs, and nuts.
• Tofu made with calcium salts is a good source of calcium, as are canned sardines and salmon with soft bones.
• Is low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars.
Low- and nonfat dairy products provide amounts of calcium that are roughly similar to the amounts in their full-fat versions.
