"Although calcium loss from bone tissue has been identified as a primary 'cause' of osteoporosis," says Gittleman, "simply supplementing with calcium or adding more calcium-rich foods to our diets may not be the best solution. Calcium can only function optimally in our bodies when it is in balance with other vitamins and minerals, especially magnesium. Megadosing with calcium can lead to deficiencies in magnesium, since both minerals compete biochemically for the same receptor sites," she cautions. She adds that therefore, ingesting an abundance of calcium is not as important as the absorption and maintenance of calcium when it comes to prevention of osteoporosis. Redmon says that calcium and magnesium are best taken in a 2:1 ratio of calcium to magnesium, which would increase the absorption and utilization of calcium. (There has been a leap in the number of calcium-magnesium combination supplements available for sale; you have many choices at your favorite health product store.)

Bone, however, has its own dynamic and calcium-sharing relationship with the rest of the body. Lieberman and Bruning explain that basically, bone, in essence, functions as a storage house for calcium, so if the body needs calcium for some other calling, it will borrow it from bone. Bone is also continuously formed and broken down in a normal continual cycle -- this exchange utilizes approximately 700 mg. of calcium daily. Now if enough calcium is ingested and absorbed in one's regular daily diet/supplement program, then there is a balance of calcium levels. "However, from the body's point of view, it is more important to maintain enough calcium in the blood to keep the heart beating regularly than it is to keep the bones strong and hard," write Lieberman and Bruning. "So if the diet is deficient in calcium, the body will always choose to maintain a certain level of calcium in the blood by drawing it out of the bone. This is accomplished through a complex system involving hormones, especially the parathyroid hormone, and vitamin D. Even if there is adequate calcium in the diet, a lack of vitamin D will seriously impair the body's ability to make use of the mineral."

Beyond Bones

Calcium also has other areas in which it boosts health. For example, Lieberman and Bruning point out that there is some evidence that this mineral may help prevent colon cancer. Epidemiological studies demonstrate that the incidence of this type of cancer is lower in those who consume more dairy foods and also are exposed to more sunlight. Several studies have suggested that the consumption of between 1,200 and 1,500 mg. of calcium daily by those who consume a high-fat diet may be protected against colon cancer.

"The authors found that within two to three months after supplementation was begun, tests of the subjects' colon linings showed that the number of fast-growing cells associated with cancer had significantly decreased, " Lieberman and Bruning note. "In a Dutch study of over 2,500 people, those with a low intake of calcium had a higher risk of being diagnosed with colorectal cancer, and a higher death rate from this form of cancer as well."

John Heinerman, Ph.D., in his book, Encyclopedia of Nature's Vitamins and Minerals, elaborates, noting that a long-term (19-year) study of middle-aged caucasian males showed that the risk of developing colorectal cancer was determined to stem from the amount of calcium and vitamin D collaborating synergistically with each other, both of which the men studied received in their diets. "The lower the amounts of both," reports Heinerman, "the greater the incidence of this cancer. Epidemiological studies in Norway, Denmark, Sweden and Finland pretty much reached the same conclusion. Men who have the lowest intake of calcium are at three times greater risk of developing colorectal cancer than are those men (in the American study) who were taking in the most calcium daily."

Two doctors from New York's Memorial Sloan-Kettering Cancer Center studied colon cells of individuals who were considered high risk for colon cancer and found that those cells were indeed dividing more quickly than what is normal. These individuals then went on a calcium supplementation program (1,250 mg. daily), and within two to three months, colon cell samples were much more normalized. "This study suggest that daily calcium intake at one and a half times the recommended daily allowance is quite useful for preventing the occurrence of this type of cancer," Heinerman writes.

Calcium is also a useful substance in cases of hypertension (also called high blood pressure). Lieberman and Bruning point out several studies illuminating calcium's positive role in this condition. One study gave 1000 mg. of calcium to 48 hypertensive men for eight weeks; this resulted in 44 percent (21 men) achieving what the authors called "therapeutically meaningful" decreases in blood pressure levels. In another study of hypertensive females, either 1,500 mg. of calcium or hypertensive pharmaceuticals were taken by subjects for four years. The results showed that those women who took calcium exhibited a significant decrease in systolic blood pressure, compared to those on the hypertensive medication who experienced a rise in blood pressure.

In their book, Lieberman and Bruning add that calcium also activates enzymes involved in digestion of fat and protein as well as in energy production. Calcium is also "involved in blood clotting and the transmission of nerve impulses," they write. "Calcium also regulates the contraction and relaxation of the muscles including the heart. And it aids in the absorption of many nutrients, especially vitamin B-12."

Calcium Supplementation

Now that you have several good reasons to be vigilant about your daily calcium intake, you should know a little about available forms and dosages. The current RDI for calcium is 1,000 milligrams for those four years of age and older; pregnant and lactating women, however, are advised to take 1,300 mg. of calcium daily. Researcher Redmon points out in his book that Dr. Kenneth Cooper, author of Preventing Osteoporosis, notes that women should ingest approximately 1,500 mg. daily. Women 50 and older, Redmon says, would benefit from 2,00 mg.

"A dizzying array of calcium supplements are available to choose from," writes Heinerman. "You should know right off the bat that supplemental calcium never comes by itself, but is always partnered with another substance. Available forms include calcium carbonate, calcium citrate, calcium phosphate, calcium lactate, and calcium gluconate."

Heinerman recommends calcium hydroxyapatite or calcium citrate.

When it comes to supplementation with calcium or any other mineral, vitamin, specialty supplement or herb, it is wise to inform your health care provider of your supplemental use, including daily dosage.

Click here for more Health Reports.

Click here to read the current Health Report!