Boning Up to Help Prevent Osteoporosis
Pharmacist Linda Willsey offers information and advice on preventing osteoporosis.
by Linda Willsey, PharmD, RPh
Ninety-nine percent of the calcium in our bodies is found in our bones, and a small amount of calcium must circulate through other body tissues to keep muscles and nerves functioning well. If your diet doesn’t provide at least 1,000 mg of calcium every day, your body will steal the calcium it needs from your bones. This can lead to osteoporosis (thinning of the bones) and fractures as you age, and women are at highest risk.
Like all living tissue, old bone is continuously broken down, or resorbed, and replaced by new bone. Until the end of our third decade, the cells responsible for bone formation (osteoblasts) are more active than the cells that break it down (osteoclasts) to permit growth, rapid healing, and increased density. Even after bones reach their full length during adolescence, they will continue to achieve greater density and strength up to age 30 in a person who exercises and eats a balanced diet.
As we age, and as a result of some medications (like prednisone and aromatase inhibitors) or health conditions, the balance of the bone remodeling cycle tips toward decreases in bone mass density. The density decrease is especially dramatic in post-menopausal women who are not on hormone replacement therapy; women can lose up to 20 percent of their bone mass in the first five years after menopause.
The National Osteoporosis Foundation (NOF) estimates that nine million people in the United States have osteoporosis and more than 48 million are at risk due to low bone mass, or osteopenia. The statistics are particularly bleak for women. 80 percent of people with osteoporosis or osteopenia are women, and 50 percent of women are likely to experience an osteoporosis-related fracture of the spine, hip, or wrist in their lifetimes. Although all women can develop osteoporosis, women of Caucasian and Asian ancestry are at highest risk. The prevalence is highest among Mexican Americans.
In addition to gender, age, and race, there are many other factors that determine who will develop osteoporosis. According to the NOF website (www.nof.org), some of these factors include:
- Family history and personal history of fractures. Susceptibility to fracture may be partly hereditary, and personal history of fracture as an adult may increase fracture risk.
- Bone structure and body weight. Small-boned women and those under 127 pounds are at greater risk.
- Menopause and/or menstrual history. Menopause, whether normal or early (brought about naturally or because of surgery), increases your risk. Women who stop menstruating due to eating disorders or excessive exercise may also be at risk.
- Lifestyle. Cigarette smoking, excessive consumption of alcohol and/or caffeine, inadequate calcium intake, and lack of weight-bearing exercise all increase your chances of developing osteoporosis.
- Medications and/or chronic diseases. Medications used to treat chronic conditions such as rheumatoid arthritis, endocrine disorders like underactive thyroid, seizure disorders, and gastrointestinal disorders may have bone-damaging side effects.
You can’t change your genes or family history, but you can make choices that may help prevent osteoporosis. Diet is critical. Make sure your are getting at least 1,000 mg of calcium and, since the body is unable to absorb calcium without adequate levels of Vitamin D, 800 to 1,000 IU of D3 (cholecalciferol) every day. Visit http://www.nof.org for age-specific calcium and Vitamin D dosage recommendations.
Do not rely on calcium supplements alone to protect your bones. Recent clinical studies have raised new concerns about a potential association between excessive doses of calcium supplements and an increased risk of cardiovascular events and even cancer. Unless otherwise directed by a health care professional, adults should not consume more than 2500 mg of calcium daily from food and supplements combined.
Until more is known, follow your mother’s advice: Drink your milk, and get most of your calcium from dairy products and other calcium-rich foods like almonds, dried figs, and broccoli. Find out how much calcium is in your diet with the Calcium Calculator at http://www.doctoroz.com/videos/calcium-calculator. Be sure to consider that foods like spinach, beet greens, legumes, and wheat bran can bind calcium and prevent absorption; try to separate calcium-rich foods from these binders by about two hours.
If your diet is calcium-deficient, you may wish to consider supplements. Food-based calcium supplements and chelated calcium, in which amino acids are bound to the mineral, are most readily absorbed by the human gut. The two most common supplemental sources of calcium are in the form of calcium carbonate, which is 40 percent elemental calcium by weight, and calcium citrate, which is about 16 percent. Calcium carbonate is very poorly absorbed and must be taken with food to ensure that stomach acid levels are sufficient to permit dissolution and absorption of calcium ions. Calcium citrate is absorbed with or without food and is a better option for bedtime dosing or for people who take acid-suppressing drugs such as Prilosec (omeprazole) or Zantac (ranitidine).
One other important detail about calcium: Whether it comes from your diet or as a supplement, take calcium in divided doses of no more than 500 mg throughout the day to ensure proper absorption.
Since there is no cure for osteoporosis, it is important for women to know their risk factors and make healthy dietary and lifestyle choices. Check out the NOF website to assess your risk factors and, if you’re over 50, consider talking to your health care provider about a bone mineral density test. Medicare will pay for a dual X-ray absorptiometry (DXA) bone mineral density test every two years for older women, but many insurance plans will not pay for the test for younger women unless they meet certain criteria (like low weight, thin frame, family history, or other personal risk factors).
Linda Willsey, Pharm D, RPh is a staff pharmacist at Community Pharmacy.