There are two ways the body can get the calcium it needs. One way is by consuming calcium-rich foods or supplements, and the other is by using calcium that already exists in the body. The body will remove calcium from bones if one does not consume enough calcium-rich foods. The calcium that is "borrowed" from the bones should eventually be replaced. However, this doesn't always occur, and it's not always possible to achieve this by simply consuming more calcium.
Recommended Amounts
For women 19 to 50 years old, 1,000 mg of calcium per day is the recommended dietary allowance; for women 51 and older, 1,200 mg. The RDA for men is 1,000 mg for those 19 to 70 years old and 1,200 mg for those 71 and older.
Food Sources
Not only milk and other dairy products, but many other foods also contain calcium. Good sources include fruits, leafy greens, beans, nuts, and some starchy vegetables.
- Dairy (cow, goat, sheep) and fortified plant-based milks (almond, soy, rice)
- Cheese
- Yogurt
- Calcium-fortified orange juice
- Winter squash
- Edamame (young green soybeans); Tofu, made with calcium sulfate
- Canned sardines, salmon (with bones)
- Almonds
- Leafy greens (collard, mustard, turnip, kale, bok choy, spinach)
- Deficiency
Calcium levels in the blood are strictly regulated. If the diet does not contain enough calcium, the bones will release it into the blood, but usually no symptoms appear. Hypocalcemia, a more severe calcium deficiency, is brought on by conditions like kidney failure, digestive tract operations like gastric bypass, or drugs like diuretics that prevent absorption.
Symptoms of hypocalcemia:
- Muscle cramps or weakness
- Numbness or tingling in fingers
- Abnormal heart rate
- Poor appetite
Source: www.hsph.harvard.edu