Calcium and Health Benefits

With many claims made about calcium and health, calcium and health benefits focus on the potential benefits of calcium in promotion and disease prevention and treatments in which the role of calcium in human body might play in bone health and osteoporosis; blood pressure regulation and hypertension; cancers of the colon, rectum, and prostate; kidney stones; and weight management.

 Bone Health and Osteoporosis

During childhood and adolescence, bones increase in size and mass. Peak bone mass is typically reached in early adulthood around age 30.

The greater peak bone mass, the longer one can delay serious bone loss with increasing age. Therefore, everyone should consume adequate amounts of calcium and vitamin D throughout childhood, adolescence, and early adulthood. With increasing age, one can delay serious bone loss the greater peak bone mass.

Porous and fragile bones characterize a disorder called osteoporosis.  For more than 10 million U.S. adults, 80% of whom are women, it is a serious public health problem.  Osteopenia, or low bone mass, which precedes osteoporosis, comprises another 34 million.

Bone Mass Calculator?

There is a connection between fractures of the hip, vertebrae, wrist, pelvis, ribs, and other bones, and osteoporosis.¹. An estimated 1.5 million fractures occur each year in the United States due to osteoporosis.²

When your calcium intake is low or you poorly absorb the calcium you ingest, bone breakdown occurs as the body uses its stored calcium (see Fun Facts on Calcium) to maintain normal biological functions.

Bone loss is part of the normal aging process.  Bone loss that occurs in postmenopausal women is due to a decrease in estrogen amounts.

When calcium intake is low or ingested calcium is poorly absorbed, bone breakdown occurs as the body uses its stored calcium to maintain normal biological functions. Bone loss also occurs as part of the normal aging process, particularly in postmenopausal women, which is due to reduced amounts of estrogen.  Being female, thin, inactive, or of advancing age; cigarette smoking, drinking an excessive amount of alcohol; or a descendent of a family of osteoporosis are some of the many factor that increase the risk of developing osteoporosis. ((National Osteoporosis Foundation. NOF osteoporosis prevention: risk factors for osteoporosis, 2003.))

There are several bone mineral density (BMD) tests available.  Since Peak bone mass is typically reached in early adulthood around age 30, the T-score from the test compares your Bone Mass Density (BMD) against that of a healthy 30-year old.  Normal bone density is a T-score between +1 and -1.  Osteopenia or low bone mass has a T-score between -1.0 to -2.5, and osteoporosis a T-score of -2.6, which indicates osteoporosis or severe bone loss.³

You may also want to take a look at your Z-score, which compares you bone mass to the average bone mass of a person of the same age, gender, and race. A zero (0) Z-score indicates that your bone mass is the same as an average person of your age, gender, and race. If your Z-score is greater than zero, it means you bones are more dense than the average person.  If you Z-score is lower, it mean that your bones are less dense than the average person.

Because the skeletons of women are smaller than those of men, and menopause accelerates bone loss, women are at the highest risk of getting osteoporosis, even though osteoporosis affects individuals of all races, ethnicities, and both genders.

An adequate intake of calcium and vitamin D, regular weight-bearing exercise, such as walking, running, or those that work against gravity, and resistance exercises, such as calisthenics and that involve weights that involve weights, are vital to developing and maintaining healthy bones throughout your life.

Health claims relating to calcium and osteoporosis for foods and supplements were authorized by the U.S. Food and Drug Administration in 1993.  ((U.S. Food and Drug Administration. Food labeling: health claims; calcium and osteoporosis, and calcium, vitamin D, and osteoporosis. Health Claims Meeting Significant Scientific Agreement SSA)).  An authorized health claim characterizes a relationship between a substance (a specific food or specific food component) and a disease (such as osteoporosis) or a health-related condition (such as high blood pressure), and are supported by scientific evidence.

In January 2010, the health claim was expanded to include vitamin D, which model health claims includes "Adequate calcium throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis" and "Adequate calcium and vitamin D as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis in later life." ((U.S. Food and Drug Administration. Food labeling: health claims; calcium and osteoporosis, and calcium, vitamin D, and osteoporosis. Health Claims Meeting Significant Scientific Agreement SSA)) 

Blood Pressure & Hypertension

Although the reductions are marked by a lack of consistency or erratic, several clinical trials have demonstrated a relationship between an increased intake of calcium and both lower blood pressure and risk of hypertension. ((Allender PS, Cutler JA, Follmann D, Cappuccio FP, Pryer J, Elliott P. Dietary calcium and blood pressure. Ann Intern Med 1996;124:825-31. PubMed abstract)) ^4 5

To a great extent, the poor quality of most studies and differences in methodologies by the authors contribute to finding any link of the effects of calcium supplements for hypertension weak at best. ((Dickinson HO, Nicolson DJ, Cook JV, Campbell F, Beyer FR, Ford GA, et al. Calcium supplementation for the management of primary hypertension in adults. Cochrane Database Syst Rev 2006;(2):CD004639. PubMed abstract))

Alternate observational and experimental studies propose that individuals who eat a vegetarian diet that is high in fiber, and minerals, such as calcium, magnesium, and potassium, and low in fat tend to have lower blood pressure. ((American Dietetic Association, Dietitians of Canada. Position of the American Dietetic Association and Dietitians of Canada: vegetarian diets. J Am Diet Assoc 2003;103:748-65. PubMed abstract)) ^6 7 8 9

The Dietary Approaches to Stop Hypertension (DASH) conducted a study by testing the effects of three different eating patterns on blood pressure:  a control "typical" American diet; one high in fruits and vegetables; and a third diet high in fruits, vegetables, and low-fat dairy products. The greatest decrease in blood pressure was the result of a diet containing dairy products, although did not evaluate the contribution of calcium to this effect. ((Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, Sacks FM, et al. A clinical trial of the effects of dietary patterns on blood pressure. N Engl J Med 1997;336:1117-24. PubMed abstract))

For a sample of DASH menu plans and additional information, visit the National Heart, Lung, and Blood Institute Web site  

Cancer of the Colon and Rectum

Results of experimental and observational studies on the potential role of calcium to prevent colorectal cancer are mixed.  Several studies associate a decreased risk of colon cancer with a high intake of calcium from low-fat dairy sources and/or supplements.  ((Slattery M, Edwards S, Boucher K, Anderson K, Caan B. Lifestyle and colon cancer: an assessment of factors associated with risk. Am J Epidemiol 1999;150:869-77. PubMed abstract)) ^10 11 12

Supplementation with Calcium Carbonate

Calcium carbonate supplementation has led to a reduced risk of  adenoma, a nonmalignant tumor in the colon, a precursor to cancer for as long as 5 years after the individual ceased taking the supplement. ((Baron JA, Beach M, Mandel JS, van Stolk RU, Haile RW, Sandler RS, et al. Calcium supplements for the prevention of colorectal adenomas. N Engl J Med 1999;340:101-7. PubMed abstract)) ¹³  ((Grau MV, Baron JA, Sandler RS, Wallace K, Haile RW, Church TR, et al. Prolonged effect of calcium supplementation on risk of colorectal adenomas in a randomized trial. J Natl Cancer Inst 2007;99:129-36. PubMed abstract))

Men and women who consumed 700-800 mg per day of calcium had a 40%-50% lower risk of developing left-side colon cancer, in two large epidemiological trials. ((Wu K, Willett WC, Fuchs CS, Colditz GA, Giovannucci EL. Calcium intake and risk of colon cancer in women and men. J Natl Cancer Inst 2002;94:437-46. PubMed abstract))

However, other observational studies found the associations were inconclusive.  ((Biasco G, Paganelli M. European trials on dietary supplementation for cancer prevention. Ann N Y Acad Sci 1999;889:152-6. PubMed abstract)) ^14 15

A clinical trial involving 36,282 postmenopausal women, daily supplementation with 1,000 mg of calcium and 400 IU of vitamin D3 for 7 years was found to produce no significant differences in the risk of invasive colorectal cancer compared to placebo in a Women's Health Initiative. ((Wactawski-Wende J, Kotchen JM, Anderson GL, Assaf AR, Brunner RL, O'Sullivan MJ, et al. Calcium plus vitamin D supplementation and the risk of colorectal cancer. N Engl J Med 2006;354:684-96. PubMed abstract))

Long studies are necessary to discover with certainty whether calcium supplementation affects colorectal cancer risk given the long latency period for colon cancer development.

Cancer of the Prostate

Several epidemiological studies have found an association between calcium intakes of 600 mg or more per day, intakes of more than 2.5 servings of dairy foods, or both and an increased risk of developing prostate cancer.^{16 17 18 19 20 21 22} However, others have found only a weak relationship, no relationship, or a negative association between calcium intake and prostate cancer risk.^{23 24 25 26} The authors of a meta-analysis of prospective studies concluded that high intakes of dairy products and calcium might slightly increase prostate cancer risk.²⁷ Additional research is needed to determine whether a man's risk of prostate cancer is affected by the amount of dairy products or calcium consumed.

Kidney Stones

Kidney stones in the urinary tract are most commonly composed of calcium oxalate. In the Women's Health Initiative clinical trial, postmenopausal women who consumed 1,000 mg of supplemental calcium and 400 IU of vitamin D per day for 7 years had a higher risk of kidney stones than subjects taking a placebo²⁸ Other studies, however, have found that high dietary calcium intakes decrease this risk.^29 30 31 For most individuals, other risk factors for kidney stones, such as high intakes of oxalates from food and low intakes of fluid, appear to play a bigger role than calcium.³²  

Weight Management

Several studies have linked higher calcium intakes to lower body weight or less weight gain over time.^{33 34 35 36} Two explanations have been proposed. First, high calcium intakes might reduce calcium concentrations in fat cells by decreasing the production of two hormones (parathyroid hormone and an active form of vitamin D) that increase fat breakdown in these cells and discourage fat accumulation.³⁷ Secondly, calcium from food or supplements might bind to small amounts of dietary fat in the digestive tract and prevent its absorption.^38 39 40 Dairy products, in particular, might contain additional components that have even greater effects on body weight than their calcium content alone would suggest.^{41 42 43 44 45 46}

Despite these findings, the results from clinical trials have been largely negative. For example, a meta-analysis of 13 randomized controlled trials concluded that neither calcium supplementation nor increased dairy product consumption has a statistically significant effect on weight reduction.⁴⁷ A more recent clinical trial found dietary supplementation with 1,500 mg/day of calcium (from calcium carbonate) for 2 years to have no clinically significant effects on weight in overweight and obese adults as compared with placebo.⁴⁸ Any apparent effects of calcium and dairy products on weight regulation and body composition are complex, inconsistent, and not well understood.^{49 50 51 52 53 54 55}