Calcium is the most abundant mineral in the human body, with over 99% of the amount present being found in the bones and teeth. For the growth and maintenance of healthy bones it is essential that we have sufficient calcium intake, otherwise we are at risk of developing osteoporosis when calcium leaching is not balanced by dietary ingestion. But calcium is not only important for the skeleton, it also has a role to play in nerve function, blood clotting, muscle health, and other areas. While calcium is a key mineral for both sexes, it is especially important to the health of women.
After the age of 35, both men and women start losing calcium from their bones. During menopause, however, the rate of loss increases rapidly for women. It is therefore vital that calcium levels are sufficient during this period if women are to avoid major skeletal problems. Not as well known is the fact that the degree of osteoporosis suffered in later life is largely dependent on the amount of bone mass achieved in early adulthood. For this reason, the building of strong bones—requiring regular calcium intake—should be a priority for women from childhood onward.
Several recent studies have also shown a link between increased calcium intake and reduced levels of pre-menstrual symptoms. Dr. Susan Thys-Jacobs of St. Luke’s-Roosevelt Hospital Center in New York found a 50% decrease in PMS symptoms for women given calcium supplementation, compared to a 30% decrease for the placebo group. Thys-Jacobs concluded that “no other drug addresses all these symptoms as effectively.” Another recently published report (Arch Intern Med. 2005;165:1246-1252), based on an epidemiological study of over 2000 women, found a strong link between calcium and vitamin D intake and the risk of PMS. The authors concluded that “a high intake of calcium and vitamin D may reduce the risk of PMS.”
Separate studies at Creighton University in Omaha, the University of Tennessee, and Purdue University showed links between increased calcium intake and weight loss. One of the researchers, Dr. Michael Zemel, reported that calcium plays a key role in metabolic disorders linked to obesity, and also that high calcium diets lead to the release of a hormone that leads to the body’s fat cells losing weight.
Clinical trials have also linked low calcium levels with high blood pressure. Argentinean research showed that women who take calcium during pregnancy may lower their children’s future risk of blood pressure problems. Studies done at Rockefeller University showed that calcium supplements were of general benefit to both mother and baby during pregnancy.
Other research, providing good news for both men and women, has linked calcium with prevention of colon cancer (University of North Carolina and Cornell University), prevention of stroke (Harvard University), and lowering of LDL (bad) cholesterol (University of Texas Southwestern Medical Center).
The recommended daily requirement of calcium depends on age: young children (4 to8 years old)need about 800mg, children up to 18 require 1300mg, adults up to 50 need 1000mg, and older adults should ingest 1200mg. These levels can be achieved through the consumption of calcium-rich foods, such as dairy products, green vegetables, soy products, sardines, and salmon, or alternatively via calcium supplements.
Calcium supplements can be useful for people who are lactose intolerant or for those who are unsure that they are eating enough of the right foods. Supplements that provide the calcium in carbonate, citrate, lactate, gluconate, or phosphate forms are well absorbed by the body. Those that combine calcium and vitamin D together are an even better option as the vitamin increases calcium absorption and provides other health benefits. Calcium in the form of oyster shell, bone meal, dolomite, and calcium hydroxyapatite should be avoided.
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