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 vascular contraction and vasodilation, muscle function, nerve transmission, intracellular signaling and hormonal secretion, though less than 1% of total body calcium is needed to support these critical metabolic functions. Serum calcium is very tightly regulated and does not fluctuate with changes in dietary intakes; the body uses bone tissue as a reservoir for, and source of calcium, to maintain constant concentrations of calcium in blood, muscle, and intercellular fluids.
The remaining 99% of the body’s calcium supply is stored in the bones and teeth where it supports their structure and function. 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 periods of growth in children and adolescents, 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.
Recommended Intakes
| Age | Male | Female | Pregnant | Lactating |
|---|---|---|---|---|
| 0–6 months | 200 mg | 200 mg | ||
| 7–12 months | 260 mg | 260 mg | ||
| 1–3 years | 700 mg | 700 mg | ||
| 4–8 years | 1,000 mg | 1,000 mg | ||
| 9–13 years | 1,300 mg | 1,300 mg | ||
| 14–18 years | 1,300 mg | 1,300 mg | 1,300 mg | 1,300 mg |
| 19–50 years | 1,000 mg | 1,000 mg | 1,000 mg | 1,000 mg |
| 51–70 years | 1,000 mg | 1,200 mg | ||
| 71+ years | 1,200 mg | 1,200 mg |
Sources of Calcium
Food
Milk, yogurt, and cheese are rich natural 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. Spinach provides calcium, but its bioavailability is poor. Most grains do not have high amounts of calcium unless they are fortified; however, they contribute calcium to the diet because they contain small amounts of calcium and people consume them frequently. Foods fortified with calcium include many fruit juices and drinks, tofu, and cereals. Selected food sources of calcium are listed in Table 2.
| Food | Milligrams (mg) per serving |
Percent DV |
|---|---|---|
| Yogurt, plain, low fat, 8 ounces | 415 | 42 |
| Mozzarella, part skim, 1.5 ounces | 333 | 33 |
| Sardines, canned in oil, with bones, 3 ounces | 325 | 33 |
| Yogurt, fruit, low fat, 8 ounces | 313–384 | 31–38 |
| Cheddar cheese, 1.5 ounces | 307 | 31 |
| Milk, nonfat, 8 ounces** | 299 | 30 |
| Soymilk, calcium-fortified, 8 ounces | 299 | 30 |
| Milk, reduced-fat (2% milk fat), 8 ounces | 293 | 29 |
| Milk, buttermilk, lowfat, 8 ounces | 284 | 28 |
| Milk, whole (3.25% milk fat), 8 ounces | 276 | 28 |
| Orange juice, calcium-fortified, 6 ounces | 261 | 26 |
| Tofu, firm, made with calcium sulfate, ½ cup*** | 253 | 25 |
| Salmon, pink, canned, solids with bone, 3 ounces | 181 | 18 |
| Cottage cheese, 1% milk fat, 1 cup | 138 | 14 |
| Tofu, soft, made with calcium sulfate, ½ cup*** | 138 | 14 |
| Ready-to-eat cereal, calcium-fortified, 1 cup | 100–1,000 | 10–100 |
| Frozen yogurt, vanilla, soft serve, ½ cup | 103 | 10 |
| Turnip greens, fresh, boiled, ½ cup | 99 | 10 |
| Kale, fresh, cooked, 1 cup | 94 | 9 |
| Ice cream, vanilla, ½ cup | 84 | 8 |
| Chinese cabbage, bok choi, raw, shredded, 1 cup | 74 | 7 |
| Bread, white, 1 slice | 73 | 7 |
| Pudding, chocolate, ready to eat, refrigerated, 4 ounces | 55 | 6 |
| Tortilla, corn, ready-to-bake/fry, one 6” diameter | 46 | 5 |
| Tortilla, flour, ready-to-bake/fry, one 6” diameter | 32 | 3 |
| Sour cream, reduced fat, cultured, 2 tablespoons | 31 | 3 |
| Bread, whole-wheat, 1 slice | 30 | 3 |
| Kale, raw, chopped, 1 cup | 24 | 2 |
| Broccoli, raw, ½ cup | 21 | 2 |
| Cheese, cream, regular, 1 tablespoon | 14 | 1 |