ORIGINALLY PUBLISHED IN THE NEW YORK TIMES OCTOBER 13, 1998
JANE E.BRODY October 13, 1998

Coral Calcium Quick Links (within article below):
Body Requirements of Calcium : PMS & Bone Disease : Effects on Cancers
: Regulating Blood Pressure :

Calcium is fast emerging as the nutrient of the decade, a substance with such diverse roles in the body that virtually no major organ system escapes its influence.

As the most abundant mineral in the body, calcium has long been recognized as vital to the formation and maintenance of strong bones and teeth. But bones, rather than serving as the final destination of calcium, are in a sense, just a starting point. They continuously release the mineral into the system where new research suggests it may play a central role in controlling blood pressure and easing premenstrual syndrome, or PMS. In addition, new studies indicate that unused dietary calcium may help to prevent colon cancer.

The recent focus on calcium comes at a time when the nation is becoming increasingly deficient both in the mineral and in vitamin D, which enables the body to absorb and use it. While the most dire effects of too little calcium and vitamin D are seen in adults, it is the country's children who have drawn some of the most intense concern, because this calcium-diminished younger generation is putting itself at much greater risk for osteoporosis - the brittle-bone disease now plaguing many older Americans.

The new research has come in a flurry. Just in the last two months, a New York research group reported that eating more calcium-rich foods reduced the risk of colon cancer in men prone to the disease, and another New York-based team described a 50 percent reduction in life-disrupting pre-menstrual symptoms among hundreds of women who took daily calcium supplements.

In August, findings reported by Boston researchers supported earlier evidence that calcium was important in controlling high blood pressure. The researchers found that blood pressure fell in women with mild hypertension after brief exposures of their skin to ultraviolet-B radiation, which stimulates the production of vitamin D.

In another report, published in the British Medical Journal in August, researchers in Argentina showed that women who were given calcium supplements during pregnancy had children whose blood pressure remained lower than average for at least the first seven years of life, which would lower their risk of later developing hypertension. And in the current issue of The American Journal of Clinical Nutrition, a research team at the University of Southern California in Los Angeles reported that adding calcium to the diet lowered blood pressure in 116 black teenagers who normally consumed little of the mineral.

The new work builds on a well-established body of research pointing to calcium's complex role in the body. Through the years, scientists have demonstrated that calcium is required for myriad body functions:
• Transmission of nerve impulses that control muscle contractions
• Release of chemicals that carry messages between nerves.
• Binding together of cells to form organs.
• Production and activity of enzymes and hormones that regulate digestion, fat metabolism, energy release and saliva production.
• Clotting of the blood to initiate wound healing.
• Secretion of hormones and other substances from glands throughout the body.
• Chemical signaling within cells.
• Growth and maturation of lining cells throughout the body.

"It's not surprising that calcium plays so many roles," said Dr. Hector F. DeLuca, a biochemist at the University of Wisconsin who is an expert on vitamin D and calcium metabolism. "Since all life originated in the sea in a bath containing calcium, we all developed systems that depend on it." Once animals emerged from the sea, leaving behind a steady supply of calcium, the body had to evolve a system for keeping calcium "at sea level" in the blood, Dr. DeLuca said. The result was the evolution of a calcium storage tank - the bones - for the body to draw on from minute to minute when blood levels of this essential mineral drop too low, as well as a mechanism to establish and replenish the body's calcium from outside sources - the diet. This mechanism involves vitamin D. In its activated form as a hormone, vitamin D enables calcium to enter the blood through the intestinal wall and be incorporated into bone.

But if the body does not receive enough dietary calcium to maintain the needed blood level, parathyroid hormone leaps to the rescue. Its job is to signal the release of calcium from the bones to restore a normal blood level of this life-sustaining mineral. If the diet is chronically deficient in calcium (or vitamin D), as it is for as many as three fourths of Americans, the bones gradually get weaker and weaker.

Back to Top of Page

PMS and Bone Disease (ATTN: WOMEN)
A chronic deficiency or imbalance of calcium is what Dr. Susan Thys-Jacobs, a gynecologist at St. Luke's Roosevelt Hospital Center in New York. believes is largely responsible for the disruptive symptoms of PMS suffered by as many as 40 percent of women. In fact. Dr. Thys-Jacobs said, PMS may be a harbinger of osteoporosis, a warning that a woman is not getting enough calcium and, as a result, is constantly losing bone.

Buoyed by the promising results of a pilot study of calcium's ability to relieve premenstrual symptoms and menstrual pain, Dr. Thys-Jacobs and colleagues at 11 other medical centers enrolled nearly 500 women with debilitating PMS in a trial of calcium's ability to relieve their monthly discomfort. For two months, the women kept careful track of the occurrence and severity of 17 symptoms grouped under four categories: mood swings, bloating, food cravings and pain. Then they were randomly assigned to take either 1,200 milligrams of calcium daily (as calcium carbonate in Turns E-X) or a look-alike placebo. The women continued on their assigned regimens and evaluated their symptoms for the next three menstrual cycles.

By the third cycle, Dr. Thys-Jacobs and her collaborators reported in The American Journal of Obstetrics and Gynecology, the overall severity of symptoms was reduced by 48 percent in the calcium group, compared with 30 percent in the placebo group. Improvement in the calcium group exceeded that of the placebo group in every category studied, both psychological and physical, and in 15 of the 17 symptoms evaluated. Most, significantly, subjects in the calcium group noted a 54 percent reduction in aches and pains, while the placebo group had a 15 percent increase in pain symptoms. The study was financed by Smith Kline Beecham, makers of Turns.

Dr. Thys-Jacobs concluded that women with PMS might have a form of functional hypoglycemia" - calcium levels in their blood and urine are normal, but only because parathyroid hormone levels are abnormally high and the hormone is continually extracting calcium from their bones to replenish the blood's supply. She suggested that all women with PMS be assessed for deficiencies of calcium and vitamin D, as indicated by their blood levels of parathyroid hormone and 25-hydroxy vitamin D. She pointed out that "80 percent of a person's vitamin D is made in the skin when exposed to sunlight, but a lot of young women are now avoiding the sun and using sunscreens.

"Their vitamin D levels are very low," Dr. Thys-Jacobs "and therefore they're not absorbing enough calcium from their diet even if they consume enough, which most young women do not."

Back to Top of Page

Effect on Cancers
Tissues throughout the body are lined with epithelial cells like the ones that form the outer layer of skin. They grow, mature, slough off and are replaced by new ones. In the lining of the colon, where cancers arise, the turnover of epithelial cells normally takes a week. But in people prone to colon cancer, these cells fail to grow and mature normally and instead immature cells proliferate rapidly. Studies in people and animals have linked high fat diets to colon cancer and shown that fatty acids and the bile acids released to process them are irritants that stimulate abnormal cell proliferation in the colon.

Dr. Martin Lipkin of the Strang Cancer Research Laboratory at Rockefeller University in New York described studies showing that calcium could bind tightly to these irritants and inhibit their ability to stimulate cell proliferation. With calcium present, as it would be on a calcium-rich diet, the cells differentiate and mature like normal epithelial cells.

Dr. Lipkin and his colleagues showed that calcium supplements could inhibit colonic cell proliferation in people susceptible to colon cancer. This finding gained support from population studies that found a link between consumption of dairy products and a reduced risk of colon cancer.

The latest study, directed by Dr. Peter R. Holt of St. Luke's Roosevelt and published two weeks ago in the Journal of the American Medical Association, showed that calcium-rich foods worked as well or better than previously thought When participants' consumption of low-fat, calcium-rich dairy products was doubled, reaching 1,200 milligrams of calcium a day, cell growth in the colon became normal. The 70 participants had undergone surgery earlier to remove benign polyps, common forerunners of colon cancer.

Dr. Lipkin, a co-author of the new study, said that animal research indicated that increasing calcium levels to .protect epithelial cells might also help prevent cancer in such organs as the breast, prostate and pancreas. Raising the animals' intake of calcium and vitamin D reduced excessive cell proliferation and induced normal development of epithelial cells in these various organs, he said.

Back to Top of Page

Regulating Blood Pressure
A person's blood pressure is influenced by many factors, including genetics, body weight, physical activity and, in some cases, salt intake. But dozens of studies since the early 1980's have also implicated calcium as a potentially important contributor to normal blood pressure, especially the calcium found in dairy products. The findings suggest that a low intake of calcium-rich dairy products may partly account for the high rates of hypertension among African-Americans,

A shortage of calcium might also contribute to the rise in blood pressure that commonly accompanies aging. Even if calcium intake is adequate, which it usually is not, most older people are deficient in the active form of vitamin D needed to absorb calcium.

While the American Heart Association's latest assessment of the relationship between high blood pressure and dietary minerals strongly emphasized sodium chloride (i.e. salt) as the prime offender, it also noted that the harmful effects of a high-salt diet were most common among people whose diets are low in calcium. Though he was a co-author of the association's statement, which was published recently in the journal Circulation, Dr. David McCarron, a hypertension specialist at Oregon Health Sciences University in Portland, champions the view that calcium-rich milk products are more effective than a low-sodium diet in curbing hypertension.

Last year, Dr. McCarron's view won major support from the surprising results of the large, federally financed DASH (Dietary Approaches to Stop Hypertension) trial. That study found that a diet rich in low fat dairy products, fruits and vegetables significantly lowered pressure in adults with high-normal pressure or mild hypertension, although participants lost no weight and continued to consume ample amounts of salt. Also, the blood pressure benefits were noted within two weeks.

The Dash diet contains up to 1,200 milligrams of calcium; participants who continued on their regular diets got only about 450 milligrams of calcium. Nearly half of Americans consume less than 450 milligrams of calcium a day, "and it's getting worse," Dr. McCarron said.

His main concern now is the "seriously deficient" diet consumed by a very large proportion of American children. Children, he said, are drinking soda and juices, not milk, and they rarely come close to eating the recommended five servings a day of fruits and vegetables. He believes parents and schools are setting children up for a lifetime of ill health.

"Calcium is a lot more than simply bone health," Dr. McCarron concluded. "It may even influence behavior," he said, citing a space shuttle study in which rats bred to become hypertensive were "frantic" on a low-calcium diet, but when fed more calcium, "they relaxed and enjoyed the space flight."

Back to Top of Page