Calcium Supplements for Osteoporosis

US Pharm. 2008;33(9):13-18.

With the aging of the baby boomers, osteoporosis is looming as a major national epidemic. Many boomers have already been diagnosed with the condition, and millions of others have osteoporosis but are unaware of its presence. For this reason, the pharmacist must be acutely aware of this condition and be ready to recommend calcium products that might help prevent further bone loss.

Prevalence of Osteoporosis
At least 200 million women around the world are afflicted with osteoporosis.¹ Osteoporosis is thought to affect 8 million women and 2 million men in the United States.^2-4 Low density of the bone at the hip is a problem for another 21.8 million.² Osteopenia is a state of low bone mass that precedes full-blown osteoporosis, affecting approximately 34 million additional Americans.^3,4 Experts estimate that osteoporosis and care of the fractures it causes are responsible for costs of $14 to $17 billion each year.^1,4 The direct costs are projected to reach $50 billion by 2040, surpassing those for such conditions as stroke, breast cancer, diabetes, and chronic lung disease.¹

Epidemiology of Osteoporosis
While osteoporosis can strike at virtually any age, there is a strong association with advancing age, as bone becomes weaker and thinner with age.⁴ Patients over the age of 50 years have a 55% risk of osteoporosis.² There is a sharp gender difference. Sixty-eight percent of those at risk are females, who have a higher risk than males due to menopausal changes (i.e., low estrogen levels).⁴ Males with decreased testosterone levels are at higher risk. Body size also plays a role; those most at risk are small women with thin bones.⁴ Those of Caucasian or Asian ethnicity are at higher risk than those of African American and Hispanic background. Cigarette smoking damages the bones and lowers estrogen levels, contributing to osteoporosis.⁵ Other risk factors include sedentary lifestyle and confinement to bed for long periods, family history, excessive use of alcohol, and poor supplementation with calcium and vitamin D.⁶

Osteoporosis in Males
Many males assume incorrectly that men do not suffer from osteoporosis. Those who become sufficiently concerned to see their physicians may be mistakenly reassured that the problem is mostly seen in females, and so they may be denied a bone mineral density test. It is unfortunate that, for these and other reasons, the diagnosis in males is usually not made until a hip or spinal fracture occurs.⁷ Understanding the risk factors for osteoporosis in males can confer a greater understanding of its significance. Some males develop osteopenia and osteoporosis due to an age-related decrease in testosterone (i.e., hypoandrogenemia).^4,7 Physicians can prescribe testosterone gel, patches, tablets, injections, or buccal systems to help correct this problem.

Manifestations of Osteoporosis
The major consequence of osteoporosis is fracture, as fragile bone is particularly subject to osteoporotic breaks. The incidence of osteoporotic fracture also serves as an indirect mea­ sure of the incidence of osteoporosis. Osteoporosis is responsible for causing a total of 1.5 million fractures yearly in Americans, including 700,000 vertebral fractures, 250,000 fractures of the wrist, and 300,000 hip fractures.⁴ Females aged 50 years have a 50% risk of sustaining an osteoporosis-induced fracture.⁸ Males of the same age have a 20% to 25% risk.^4,8

Experts predict that the incidence of hip fracture will mushroom to 6.3 million yearly in 2050.¹ Hip fractures constitute a significant risk to health and independence. Patients who experience hip fracture have a 20% risk of death within six to 12 months.^1,8 Those who survive nonetheless endure the psychological and financial burden of hospitalization, surgery, and rehabilitation. Further, hip fracture leads to permanent institutionalization, permanent disability, and loss of independence for as many as one-third of patients.⁸ Less than one-third of patients who endure hip fracture will ever return to the full level of functioning they enjoyed prior to the incident.¹

Assessing Osteoporosis
Osteoporosis is assessed via bone mineral density tests of the hip, spine, wrist, finger, shin, or heel.⁹ The hip dual-energy x-ray absorptiometry (DXA or DEXA) exam yields a T-score, comparing the individual's bone mineral density to that of a 30-year-old healthy adult with optimal scores.^1,2 If the T-score is -1 or less, the patient has a normal bone mineral density. If the T-score falls in the range of -1.0 to -2.5, the patient has low bone mineral density, or osteopenia. If the T-score falls below -2.5, the patient is diagnosed with full osteoporosis.

Calcium Supplements
Calcium is critical in preventing osteoporosis. Prospective, controlled trials have demonstrated that administration of calcium reduces bone loss due to aging by as much as 50%.⁸ Unfortunately, the average American female takes in only 600 mg of calcium daily, placing her at a high risk of osteoporosis.² Large segments of the American population fail to take in adequate calcium. In the age range 6 to 11 years, 44% of boys and 58% of girls fail to meet the recommended intakes. The figures rise to 64% of boys and 87% of girls in the ages 12 to 19, and reach 55% for men and 78% for women at ages 20 and above.⁹

The pharmacist can provide a good deal of information about choosing an appropriate calcium supplement. Calcium carbonate is the most common form of the element in commercially available supplements (e.g., Caltrate, OsCal, Tums, Viactiv). The molecule contains 40% elemental calcium. An alternative is calcium citrate (e.g., Citracal), which is 21% calcium. The optimal recommended intakes of calcium for different demographic groups are provided in Recommended Calcium Intakes.

Coral calcium is promoted with outlandish claims for treatment and prevention of serious medical conditions, such as cancer, lupus, multiple sclerosis, and heart disease, on the basis of a purported claim of increased bioavailability. In 2003, the FDA and Federal Trade Commission (FTC) charged the marketers of Coral Calcium Supreme and other operators with making these false and unsubstantiated claims.¹⁰ One would think that combined FDA/FTC action would stop further scamming. However, a close examination of several Web sites reveals a fount of misinformation hawked to gullible consumers by the same unscrupulous marketers that were the subject of the 2003 FDA/FTC charges.^11,12 Typical statements made by the nonphysician scammers include the false assertion that cancer is caused by a lack of free oxygen in the body, a "fact" unknown to the real medical profession.¹²

Vitamin D
Vitamin D is essential in absorbing calcium from the gastrointestinal (GI) tract and ensuring bone health.² Those aged 19 to 50 years should take in 200 IU daily, those aged 51 to 70 require 400 IU daily, and those 71 and older should ingest 600 IU daily.⁵ Some experts believe that higher intakes (800-1,000 IU) would further reduce the risk of fracture in older patients.² Patients who do not get adequate exposure to sunlight would be well-advised to increase their vitamin D intake to 700 to 800 mg per day.

Patients should be cautioned not to ingest excess vitamin D. Most calcium supplements also include vitamin D. Many patients also take a daily multivitamin. The pharmacist can obtain bottles of both products when making a recommendation and point out the amounts of vitamin D the patient ingests daily. If the amounts are clearly in excess of the figures given above, the patient may be at risk of hypervitaminosis D. This is more common in patients who have heeded incorrect advice and ingest excessive vitamins each day.

Adverse Effects of Calcium Supplementation
Excessive calcium intake is not without adverse effects. Calcium carbonate requires an acidic environment for absorption, and should be taken with meals, a possible barrier to compliance. Many patients discover that calcium carbonate causes such problems as flatulence and bloating because the pH interaction between acidic gastric contents and the higher pH calcium compound produces gas, the same type of gas one sees when mixing sodium bicarbonate and vinegar.

On the other hand, water-soluble calcium citrate is a more attractive option for several reasons. Calcium citrate can be taken without regard to meals, does not require the acidic environment for absorption, and does not cause flatulence or bloating.^9,13 Calcium citrate is also preferable in patents with decreased stomach acid, whether it is their normal condition or a result of taking H₂-blockers (e.g., Pepcid AC, Zantac, Tagamet, Axid) or proton pump inhibitors (e.g., Aciphex, Nexium, Prevacid, Protonix).¹³

Calcium supplements can also cause constipation. Patients should be advised to begin a regimen of increased fiber and fluid intake to help offset the problem. Pharmacists can advise three daily doses of psyllium or methylcellulose with the suggested amount of fluid and also stress the healthy benefits of increasing fluid intake at other times. Calcium citrate may produce less constipation.¹³

Kidney stones are a possible adverse event.² They are a known problem with calcium carbonate. However, there is some evidence to demonstrate that calcium citrate is far less prone to produce stones, perhaps due to its water solubility.^14,15

Maximizing Calcium Absorption
The percentage of calcium absorbed is inversely proportional to the total amount ingested.⁹ Thus, it is counterproductive for patients with spotty compliance to take their total daily doses at one sitting. Absorption of calcium is optimal when the patient takes divided doses, with single doses not exceeding 500 to 1,000 mg.^2,9 Furthermore, plants often contain chemicals that hamper calcium absorption from the GI tract by binding with it. One interacting substance is oxalic acid, which is found in spinach, collard greens, sweet potatoes, rhubarb, and beans.⁹ Another is phytic acid, which is found in whole grain bread, beans, seeds, nuts, grains, and soy isolates. Patients should be cautioned to take their calcium supplements at times other than when ingesting these foods.

Other Interventions
Numerous additional interventions for osteoporosis prevention and treatment are beyond the scope of the pharmacist's role in self-care. They include weight-bearing exercise, such as walking, aerobics, and resistance exercises.¹³ The regimen for a specific patient is best controlled and monitored by a physical therapist or physician.

REFERENCES
1. Lane NE. Epidemiology, etiology, and diagnosis of osteoporosis. Am J Obstet Gynecol. 2006;194(suppl):S3-S11.
2. Levine JP. Pharmacologic and nonpharmacologic management of osteoporosis. Clin Cornerstone. 2006;8:40-53.
3. Gass M, Dawson-Hughes B. Preventing osteoporosis-related fractures: an overview. Am J Med. 2006;119(suppl 1):S3-S11.
4. Osteoporosis. National Institute of Arthritis and Musculoskeletal and Skin Diseases. www.niams.nih.gov/Health_Info/Bone/Osteoporosis/Default.asp. Accessed July 25, 2008.
5. Osteoporosis. U.S. Department of Health and Human Services. www.4woman.gov/faq/osteopor.htm. Accessed July 25, 2008.
6. Rivlin RS. Keeping the young-elderly healthy: is it too late to improve our health through nutrition? Am J Clin Nutr. 2007:86(suppl):1572S-1576S.
7. Wright VJ. Osteoporosis in men. J Am Acad Orthop Surg. 2006;14:347-353.
8. Keen R. Osteoporosis: strategies for prevention and treatment. Best Pract Res Clin Rheumatol. 2007;21:109-122.
9. Dietary supplement fact sheet: calcium. National Institutes of Health. http://dietary-supplements.info.nih.gov/factsheets/calcium.asp. Accessed July 25, 2008.
10. FTC and FDA take new actions in fight against deceptive marketing. Federal Trade Commission. www.ftc.gov/opa/2003/06/trudeau.shtm. Accessed July 25, 2008.
11. Bob Barefoot's--Cure America! www.robertbarefoot.com/t-CureAmerica.aspx. Accessed July 25, 2008.
12. Coral calcium and disease. www.robertbarefoot.com/t-CoralCalciumDisease.aspx. Accessed July 25, 2008.
13. Mauck KF, Clarke BL. Diagnosis, screening, prevention, and treatment of osteoporosis. Mayo Clin Proc. 2006;81:662-672.
14. Sakhaee K, Baker S, Zerwekh J, et al. Limited risk of kidney stone formation during long-term calcium citrate supplementation in nonstone forming patients. J Urol. 1994;152:324-327.
15. Sakhaee K, Poindexter JR, Griffith CS, Pak CY. Stone forming risk of calcium citrate supplementation in healthy postmenopausal women. J Urol. 2004;172:958-961.

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