Note the benefits of calcium supplementation
Good news for your older female patients: Calcium, or calcium in combination with vitamin D, may prevent osteoporosis in those age 50 and older, results from a new meta-analysis show.1
Women need to be informed on osteoporosis: It is estimated that 10 million people older than age 50 have osteoporosis in the United States, and almost 34 million have low bone mass that puts them at increased risk for developing the disease, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).2 Four out of five people who have osteoporosis are women, estimates NIAMS. One in two women older than age 50 will have an osteoporosis-related fracture in their lifetime, according to NIAMS statistics.2
To perform the meta-analysis, researchers at University of Western Sydney's Center for Complementary Medicine Research identified 29 randomized trials via electronic databases, supplemented by a hand-search of reference lists, review articles, and conference abstracts. All randomized trials that recruited people ages 50 years or above were eligible. The main outcomes were fractures of all types and percentage change of bone mineral density from baseline. Data were pooled by use of a random-effect model.
In trials that reported fracture as an outcome (17 trials, n = 52,625), treatment was associated with a 12% risk reduction in fractures of all types, the scientists note. In trials that reported bone mineral density as an outcome (23 trials, n = 41,419), the treatment was associated with a reduced rate of bone loss of 0.54% (0.35–0.73; p < 0.0001) at the hip and 1.19% (0.76–1.61%; p < 0.0001) in the spine. Reduction of fracture risk was significantly greater (24%) in trials in which the compliance rate was high. Scientists report that treatment effect was better with calcium doses of 1,200 mg or more than with doses less than 1,200 mg, and with vitamin D doses of 800 IU or more than with doses less than 800 IU.
The results showed the importance of starting supplements at about the age of 50, when bone mineral loss begins to accelerate, says Benjamin Tang, MD, an associate researcher at the university center and lead author of the research paper. This persistence pays off, he notes: People who reported taking their supplements at least 80% of the time experienced a 24% reduction in fractures, while those who were less rigorous with their routine saw the benefit cut in half.
Encourage vitamin D
When talking with women about calcium's role in osteoporosis prevention, be sure to talk about vitamin D as well. Calcium cannot be absorbed without vitamin D. Milk fortified with vitamin D, including lactose-free milk, is a good source, as is sunlight. Being in the sun for just 15 minutes a day helps skin produce vitamin D and activates vitamin D in the body.3 Recommended daily levels of vitamin D are 10 mcg for women ages 51–70 and 15 mcg for women older than age 70.3
Clinicians often overlook vitamin D deficiency, and inadequate supplementation may be more widespread than most realize, a recent study indicates.4 More than half of North American women receiving therapy to treat or prevent osteoporosis have vitamin D inadequacy, the research suggests.4
The epidemic of low vitamin D levels should be highlighted, says Anita Nelson, MD, professor in the Obstetrics and Gynecology Department at the University of California in Los Angeles (UCLA) and medical director of the women's health care programs at Harbor-UCLA Medical Center in Torrance. In adults, vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases, and cardiovascular diseases.5
Good for breast health?
Women who consume higher amounts of calcium and vitamin D also may have a lower risk of developing premenopausal breast cancer, according to results of a 2007 research study.6 While data from animal studies have linked calcium and vitamin D to breast cancer prevention, results from previous epidemiologic studies on humans have been less conclusive.
Study details
Researchers assessed 10,578 premenopausal and 20,909 postmenopausal women age 45 and older who were part of the Women's Health Study. At the beginning of the study, the women completed a questionnaire about their medical history and lifestyle, and they completed a food frequency questionnaire that detailed how often they consumed certain foods, beverages, and supplements during the previous year.
For every six months during the first year and then every subsequent year, participants returned follow-up questionnaires indicating whether they had been diagnosed with breast cancer.
Over an average of 10 years of follow-up, 276 premenopausal women and 743 postmenopausal women developed breast cancer. Premenopausal women who consumed more total calcium and vitamin D were at a lower risk of developing breast cancer; the multivariate hazard ratios (95% confidence intervals) in the highest quintile group relative to the lowest one were 0.61 (0.40–0.92) for total calcium (P = 0.04 for trend) and 0.65 (0.42–1.00) for total vitamin D intake (P = 0.07 for trend).
References
- Tang BM, Eslick GD, Nowson C, et al. Lancet. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: A meta-analysis. Lancet 2007; 370:657-666.
- National Institute of Arthritis and Musculoskeletal and Skin Diseases. Osteoporosis. Accessed at www.niams.nih.gov.
- American College of Obstetricians and Gynecologists. Osteoporosis. Accessed at www.acog.org.
- Holick MF, Siris ES, Binkley N, et al. Prevalence of Vitamin D inadequacy among postmenopausal North American women receiving osteoporosis therapy. J Clin Endocrinol Metab 2005; 90:3,215-3,224.
- Holick MF. Vitamin D deficiency. N Engl J Med 2007;357:266-281.
- Lin J, Manson JE, Lee IM, et al. Intakes of calcium and vitamin D and breast cancer risk in women. Arch Intern Med 2007; 167:1,050-1,059.
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