Calcium is the most abundant mineral in the human body. About 99% of calcium is in the bones and teeth. Calcium keeps the bones and teeth strong, plays a role in muscle contraction and blood clotting, and is important in nerve impulse transmission.
The most absorbable form of calcium is calcium citrate. Calcium carbonate is basically chalk and is barely absorbable by the body.
1000 mg
Deficiency leads to bone loss, which may lead to osteoporosis, or to a disease called rickets. Overconsumption of animal protein may lead to calcium depletion.
A low level of calcium in the blood and tissues can cause hypocalcemia. This involves sensations of tingling and numbness and muscle twitches.
You can take too much calcium. Taking more than 2,000 mg of any kind of calcium in a day can affect the absorption of iron. Too much calcium carbonate can cause severe kidney damage and other problems related to calcium toxicity.
Excess calcium in the blood can lead to deposits in the heart and kidneys.
Calcium requires Vitamin D for absorption. Calcium should be taken with magnesium. Calcium constipates, and magnesium is a laxative, so the two cancel each other out.
Too much calcium hinders iron absorption.
Dairy products, leafy green vegetables, nuts and seeds, tofu and dried fruit are all good sources of calcium.
Calcium is used to treat osteoporosis, rickets, high blood pressure, PMS, gingivitis and migraine headaches
Calcium decreases the effectiveness of tetracycline. Albuterol and other asthma medication decreases calcium levels in the body. Thyroid hormone increases urinary loss of calcium. Caffeine leaches calcium from the bones. And calcium binds with our good friend Cipro. Birth control pills are associated with increased levels of calcium.
Bendich, A.
Micronutrients in women's health and immune function.
Nutrition. 2001 Oct;17(10):858-67.
One interesting point from the article: Symptoms of premenstrual syndrome affect the vast majority of menstruating women, and calcium supplementation significantly reduces physical and emotional symptoms. Premenstrual syndrome in fact might be a predictor of osteoporosis induced by low calcium intake.
Singh N, Singh PN, Hershman JM.
Effect of calcium carbonate on the absorption of levothyroxine.
JAMA. 2000 Jun 7;283(21):2822-5.
CONCLUSIONS: This study of 20 patients receiving long-term levothyroxine replacement therapy indicates that calcium carbonate reduces T(4) absorption and increases serum thyrotropin levels. Levothyroxine adsorbs to calcium carbonate in an acidic environment, which may reduce its bioavailability