Osteoporosis is a common bone disorder that causes a progressive loss in bone density and mass. As a result, bones become thin, weakened, and easily fractured. It is estimated that more than 1.3 million osteoporosis-associated (or “osteoporotic”) fractures occur every year in the United States, primarily of bone within the spine (the vertebrae), the hip, and the forearm near the wrist. (See “Patient education: Bone density testing (Beyond the Basics)”.)
A number of treatments can help to prevent loss of bone and treat low bone mass. However, the first step in preventing or treating osteoporosis is to consume foods and drinks that provide calcium, a mineral essential for bone strength, and vitamin D, which aids in calcium breakdown and absorption. (See “Patient education: Osteoporosis prevention and treatment (Beyond the Basics)”.)
CALCIUM AND VITAMIN D BENEFITS
Good nutrition is important at all ages to keep the bones healthy.
●Taking calcium reduces bone loss and decreases the risk of fracturing the vertebrae (the bones that surround the spinal cord).
●Consuming calcium during childhood (eg, in milk) can lead to higher bone mass in adulthood. This increase in bone density can reduce the risk of fractures later in life.
●Calcium may also have benefits in other body systems by reducing blood pressure and cholesterol levels.
●Calcium and vitamin D supplements may help prevent tooth loss in older adults.
RECOMMENDATIONS FOR CALCIUM
General recommendations — Premenopausal women and men should consume at least 1000 mg of calcium, while postmenopausal women should consume 1200 mg (total diet plus supplement). You should not consume more than 2000 mg of calcium per day (total diet plus supplement) due to the risk of side effects.
Calcium in the diet — The primary sources of calcium in the diet include milk and other dairy products, such as hard cheese, cottage cheese, or yogurt, as well as green vegetables, such as kale and broccoli (table 1). Some cereals, soy products, and fruit juices are fortified with calcium.
Calcium supplements — The body is able to absorb calcium contained in supplements as well as from dietary sources. If it is not possible to get enough calcium from dietary sources, consult a health care provider to determine the best type, dose, and timing of calcium supplements. The table shows the calcium and vitamin D content in commonly available supplements (table 2).
●Calcium carbonate is effective and is the least expensive form of calcium. It is best absorbed with a low-iron meal (such as breakfast). Calcium carbonate may not be absorbed well in people who also take a specific medication for gastroesophageal reflux (called a proton pump inhibitor or H2 blocker), which blocks stomach acid. (See “Patient education: Gastroesophageal reflux disease in adults (Beyond the Basics)”.)
●Many natural calcium carbonate preparations such as oyster shells or bone meal contain some lead.
●Calcium citrate is well absorbed in the fasting state as well as with a meal.
●Calcium doses above 500 mg are not absorbed as well as smaller doses, so large doses of supplements should be taken in divided doses (eg, in the morning and evening).
●Calcium supplements do not replace other osteoporosis treatments such as hormone replacement, bisphosphonates (eg, risedronate [sample brand name: Actonel] and alendronate [brand name: Fosamax]), and raloxifene (brand name: Evista).
Calcium and vitamin D supplements alone are usually insufficient to prevent age-related bone loss, although they may be beneficial in some subgroups (older adults, those with very low intake). In most patients with or at risk for osteoporosis, the addition of medication or hormonal therapy is necessary in order to slow the breakdown and removal of bone (ie, resorption). (See “Patient education: Osteoporosis prevention and treatment (Beyond the Basics)”.)
Underlying gastrointestinal diseases — Patients who do not adequately absorb nutrients from the gastrointestinal tract (due to malabsorption) may require more than 1000 to 1200 mg of calcium per day. In such cases, a health care provider can help to determine the optimal dose of calcium.
Medications — All medications should be discussed with a health care provider to ensure that possible interactions with calcium are identified. Certain medications change the amount of calcium that is absorbed and/or excreted. As an example, loop diuretics (eg, furosemide [sample brand name: Lasix]) increase the amount of calcium excreted in the urine.
On the other hand, thiazide diuretics (eg, hydrochlorothiazide) can reduce levels of calcium in the urine, potentially reducing the risk of bone loss and kidney stones. (See ‘Kidney stones’ below.)
Side effects of calcium — Calcium is usually easily tolerated when it is taken in divided doses several times per day. Some people experience side effects related to calcium, including constipation and indigestion. Calcium supplements interfere with the absorption of iron and thyroid hormone, and therefore, these medications should be taken at different times.
Kidney stones — There is no evidence that consuming large amounts of calcium (from foods and drinks) increases the risk of kidney stones, or that avoiding dietary calcium decreases the risk. In fact, avoiding dairy products is likely to increase the risk of kidney stones.
However, use of calcium supplements may increase the risk of kidney stones in susceptible individuals by raising the level of calcium in the urine. This is particularly true if the supplement is taken between meals or at bedtime, and this is one of the reasons we prefer for patients to get as much of their calcium requirement through dietary means. (See “Patient education: Kidney stones in adults (Beyond the Basics)”.)
IMPORTANCE OF VITAMIN D
Vitamin D decreases bone loss and lowers the risk of fracture, especially in older men and women. Along with calcium, vitamin D also helps to prevent and treat osteoporosis. To absorb calcium efficiently, an adequate amount of vitamin D must be present.
Vitamin D is normally made in the skin after exposure to sunlight. (See “Patient education: Vitamin D deficiency (Beyond the Basics)”.)
Recommendations for vitamin D — The current recommendation is that men over 70 years and postmenopausal women consume at least 800 international units (20 micrograms) of vitamin D per day. Lower levels of vitamin D are not as effective, while high doses can be toxic, especially if taken for long periods of time. Although the optimal intake has not been clearly established in premenopausal women or in younger men with osteoporosis, 600 international units (15 micrograms) of vitamin D daily is generally suggested.
Vitamin D is available as an individual supplement and is included in most multivitamins and some calcium supplements (table 2). Milk is a relatively good dietary source of vitamin D, with approximately 100 international units (2.5 micrograms) per cup (240 mL), and salmon has 800 to 1000 international units (20 to 25 micrograms) of vitamin D per serving (table 3).
Most healthy people don’t need to check with their health care provider before taking standard doses of vitamin D and don’t need monitoring of vitamin D levels if they are not being treated for vitamin D deficiency. However, recommendations for vitamin D supplementation may be different in people with certain underlying medical conditions, such as sarcoidosis or lymphoma. In these situations, a provider will determine if supplements are needed; if so, the person’s vitamin D and calcium levels should be monitored with regular tests.
Osteoporosis is characterized by low bone mass, microarchitectural disruption, and increased skeletal fragility. Multiple therapeutic regimens have been designed to prevent or treat bone loss in postmenopausal women and older adults. The first step in the prevention or treatment of osteoporosis is ensuring adequate nutrition, particularly maintaining an adequate intake of calcium and vitamin D. Vitamin D enhances intestinal absorption of calcium and phosphate. Low concentrations of vitamin D are associated with impaired calcium absorption, a negative calcium balance, and a compensatory rise in parathyroid hormone (PTH), which results in excessive bone resorption.
Calcium and vitamin D supplementation in the treatment of osteoporosis will be reviewed here. Detailed information regarding pharmacologic therapy for osteoporosis and the role of calcium in the pathogenesis of osteoporosis is discussed separately. (See “Overview of the management of osteoporosis in postmenopausal women” and “Treatment of osteoporosis in men” and “Pathogenesis of osteoporosis”.)
The optimal intake of calcium and vitamin D is uncertain. Based upon the meta-analyses discussed below, we suggest 1200 mg of calcium (total of diet and supplement) and 800 international units of vitamin D daily for postmenopausal osteoporosis. Although the optimal intake (diet plus supplement) has not been clearly established in premenopausal osteoporosis (or in males with osteoporosis), 1000 mg of calcium (total of diet and supplement) and 600 international units of vitamin D daily are generally suggested. We recommend not administering yearly high-dose (eg, 500,000 international units) vitamin D.
These recommendations are consistent with the Institute of Medicine Dietary Reference Intakes for calcium and vitamin D . The American Geriatrics Society and the National Osteoporosis Foundation recommend a slightly higher dose of vitamin D supplementation (at least 1000 and 800 to 1000 international units daily, respectively), as well as calcium supplements, to older adults (≥65 years) to reduce the risk of fractures and falls.
Calcium is important for bone health throughout your life. Although diet is the best way to get calcium, calcium supplements may be an option if your diet falls short.
Before you consider calcium supplements, be sure you understand how much calcium you need, the pros and cons of calcium supplements, and which type of supplement to choose.
The benefits of calcium
Your body needs calcium to build and maintain strong bones. Your heart, muscles and nerves also need calcium to function properly.
Some studies suggest that calcium, along with vitamin D, may have benefits beyond bone health: perhaps protecting against cancer, diabetes and high blood pressure. But evidence about such health benefits is not definitive.
The risks of too little calcium
If you don’t get enough calcium, you could face health problems related to weak bones:
- Children may not reach their full potential adult height.
- Adults may have low bone mass, which is a risk factor for osteoporosis.
Many Americans don’t get enough calcium in their diets. Children and adolescents are at risk, but so are adults age 50 and older.