Bone Health

Approximately 44 million American women and men aged 50 and older have osteoporosis (severe bone loss) or osteopenia (mild bone loss), with women being affected about twice as often as men. At least 1.5 million fractures of the hip, vertebra (back or neck), or wrist occur each year in the United States as a result of osteoporosis, and the annual cost of treating this disorder is nearly $14 billion and rising. Unfortunately, the toll in human suffering and loss of independence is even greater.

In this issue of Ask the Doctor, we will discuss the risk factors for osteoporosis and some key nutrients you can add to your diet that can minimize bone loss and reduce your chances of developing this disease.

Q. What are the risk factors for osteoporosis?

A. Small body frame, underweight, Caucasian or Asian race, a sedentary lifestyle, cigarette smoking, excessive alcohol or caffeine intake, high intake of carbonated beverages (especially colas), and having other family members with osteoporosis all increase personal risk of developing the disease. Certain medical conditions, including diabetes, celiac disease, hyperthyroidism, rheumatoid arthritis, chronic obstructive lung disease, hyperadrenalism, and hyperparathyroidism, are all associated with an increased risk of osteoporosis. Some medications increase the rate at which bone is lost; these include drugs prescribed for the treatment of seizures, drugs used for blood thinning, steroids such as prednisone, aluminum-containing antacids, and loop diuretics (furosemide {Lasix}).

Q. Isn’t bone loss just a normal consequence of aging?

A. Although bone mass normally declines after the age of 35, bone loss severe enough to cause fractures after just minor trauma (such as bump or fall) seems to be a relatively new phenomenon. Osteoporosis was rare in the late 19^th century, and it was not until around 1920 that the condition began to attract attention among doctors. Since that time, the percentage of people who develop osteoporosis has continued to increase. For example, the age-adjusted prevalence of osteoporosis in England and Sweden double between 1950 and 1980. In addition, the percentage of elderly people with osteoporosis in some developing countries is lower than that of elderly Americans, despite lower calcium intakes in the developing countries, further suggesting that osteoporosis is a disease of modern civilization.

Q. Can osteoporosis be prevented?

A. Engaging in regular weight bearing exercise, avoiding excessive consumption of alcohol and caffeine, and quitting smoking will slow the rate of bone loss. Eating adequate, but not excessive, amounts of protein also enhances bone health. In addition, a growing body of research has shown that supplementing with various vitamins and minerals may not only help prevent, but in some cases actually reverse, bone loss. At least 15 different nutrients have been found to play a role in bone health.

Q. What type of calcium is best?

A. For most people, calcium salts are absorbed about the same, between 30% and 40% of the administered dose. People who low stomach acid (hypochlorhydria) should not use calcium carbonate, because that form of calcium is absorbed poorly in the absence of stomach acid. Calcium phosphate may be preferable for many older people, because phosphorus is necessary for normal bone formation, the phosphorus intake of older people is often low, and calcium supplements inhibit the absorption of phosphorus.

Also, calcium bound to phosphorus is the form in which calcium in the bone is stored, and it has a much greater bone activity than other forms.

Q. How much vitamin D is needed to promote strong bones?

A. Because vitamin D is produced when the ultraviolet rays from the sun hit skin, people who stay out of the sun, wear sunscreen, or live in a northern latitude (such as Boston or Seattle) where less ultraviolet light reaches the skin, are at increased risk of vitamin D deficiency. In addition, aging decreases a person’s ability to synthesize vitamin D in the skin. Results from five research trials on vitamin D found that supplementation with 700-800 IU of vitamin D per day decreased the number of hip fractures by 26%, but 400 IU per day was ineffective. In addition to enhancing bone health, vitamin D improves nerve and muscle function in older people, thereby reducing their chances of falling down. Supplementation of elderly women with 800 IU of vitamin D per day has been shown to decrease the number of falls by about 50%.

Q. Is that much vitamin D safe?

A. The Food and Nutrition Board of the Institute of Medicine established a “safe upper limit” of 2,000 IU per day in 1997. More recent research suggests that up to 4,000 IU of vitamin D per day is safe for the average person. However, you likely don’t need nearly this much to address most bone issues.

Q. Why would nutrients besides calcium and vitamin D is important?

A. Bone is living tissue, constantly remodeling itself and engaging in numerous biological functions. Like other tissues in the body, bone has a wide range of nutritional needs. The typical refined and processed American diet has been depleted of many different vitamins and minerals, some of which play a key role in promoting bone health. Not getting enough of one or more of these micronutrients may be and important contributing factor to the modern epidemic of osteoporosis. In addition, supplementing with calcium may cause a loss of magnesium, zinc, silicon, manganese, and phosphorus, unless these nutrients are also provided.

Q. What nutrients besides calcium and vitamin D promote healthy bones?

A. Magnesium, zinc, copper, manganese, vitamin K, boron, strontium, silicon, folic acid, vitamin B6, vitamin B12, phosphorus, and vitamin C have all been shown to play a role in bone health. Following is a brief description of the role that each of these 15 nutrients play in building healthy bones.

Calcium: A component of the mineral crystals that make up bone.

Vitamin D: Enhances calcium absorption, prevents falls by improving nerve and muscle function.

Magnesium: Important for bone mineralization (accumulation of minerals which form bones). Magnesium deficiency is associated with abnormal bone mineral crystals in humans. In an open clinical trial, magnesium supplementation increased bone mineral density by an average 5% after 1-2 years in postmenopausal women.

Copper: Laboratory research has found that copper promotes bone mineralization and decreases bone loss, and that osteoporosis can develop if the diet is deficient in copper. Western diets often contain less copper than the amount recommended by the National Academy of Sciences. In a 2-year double-blind trail, copper supplementation reduced bone loss by 90% in middle-aged women, compared with a placebo.

Zinc: Like magnesium, zinc is important for bone mineralization, and also has been shown to decrease bone loss. Low dietary zinc intake was associated with increased fracture risk in a study of middle-aged and elderly men. The zinc content of the diet is frequently low; a study of elderly low-income people found they were consuming only half the Recommended Dietary Allowance for this mineral.

Manganese: Plays a role in the creation of the connective-tissue components of bone. Manganese deficiency in laboratory tests resulted in low bone mineral density and weak bones. Manganese deficiency may be associated with the development of osteoporosis.

Boron: Supports creation of bone-protecting hormones such as estrogen, testosterone, and DHEA. Boron supplementation prevented bone loss in experimental studies. In human volunteers consuming a low-boron diet, boron supplementation decreased urinary calcium excretion by 25-33%, a change that may indicate reduced bone loss.

Silicon: Plays a role in the synthesis of the connective-tissue components of bone. Silicon deficiency has been associated with bone abnormalities. In an observational study, higher dietary silicon intake correlated with higher bone mineral density. In a clinical trial, administration of an organic silicon compound increased bone mineral density of the femur (or thigh bone) in postmenopausal women.

B vitamins (folic acid, vitamin B6, and vitamin B12): These three B vitamins have been shown to lower blood levels of homocysteine, a breakdown product of the amino acid methionine. An elevated homocysteine concentration is a strong and independent risk factor for fractures in older men and women. Homocysteine levels increase around the time of menopause, which may explain in part why bone loss accelerates at that time. In a 2-year double-blind trial, supplementation of elderly stroke patients with folic acid and vitamin B12 reduced the number of hip fractures by 78%, compared with a placebo.

Strontium: This trace mineral is incorporated into bone and appears to increase bone strength. It also stimulates bone formation and inhibits bone breakdown. Controlled trials have demonstrated that strontium supplementation of postmenopausal women increases bone mineral density and decreases fracture risk.

Vitamin K: Best known for its effect on blood clotting, vitamin K is also required for the creation of osteocalcin, a unique protein found in bone that participates in the mineralization process. The amount of vitamin K needed for optimal bone health appears to be greater than the amount needed to prevent bleeding. Vitamin K levels tend to be low in people with osteoporosis. In randomized clinical trials, supplementation of postmenopausal women with vitamin K prevented bone loss and reduced the incidence of fractures.

Q. Which form of vitamin K is best?

A. Two forms of vitamin K compounds are present in food: vitamin K1 and vitamin K2. Vitamin K1 (also called phylloquinone) is present in leafy green vegetables and some vegetable oils, and vitamin K2 is found in much smaller amounts in meat, cheese, eggs, and natto (fermented soybeans).

To make things a little more complicated, Vitamin K2 itself can occur in more than one form. The two most important to this discussion are menaquinine-4 (MK-4, also called menatetrenone), which is licensed as a prescription drug in Japan, and Menaquinone-7 (MK-7), which is extracted from natto.

Research suggests that MK-7 from natto may be an ideal form of vitamin K. The biological activity of MK-7 in laboratory studies was 17 times higher than that of vitamin K1 and 130 times higher than that of MK-4. After oral administration, MK-7 was better absorbed and persisted in the body longer, compared with MK-4 and vitamin K1. Although both have shown ability to prevent osteoporosis in laboratory research, a much lower dosage (600 times lower) of MK-7 is required, compared to MK-4, to obtain beneficial effects.

Thus, MK-7 has greater biological activity, greater bioavailability, and possibly more potent effects on bone, compared with other forms of vitamin K. The potential value of MK-7 for bone health is supported by an observational study from Japan, in which increasing natto consumption was associated with a lower risk of hip fracture. While additional research needs to be done, the available evidence suggests that the best forms of vitamin K for long-term use at physiological doses are MK-7 and vitamin K1.

Q. Why is strontium so important in building strong bones?

A. Strontium is of great interest to bone health researchers and has been studied in very high doses. Surprisingly, lower doses are not only safer for long-term supplementation, but may in fact have a greater impact on bone health than very high doses. Too little, and bone density is impaired; too much and health may be impaired. This is a case where dosing needs to be just right for optimal impact. Therefore, until more is known, it is wise to keep supplemental strontium at less than 6 mg per day.

Q. Can people taking osteoporosis medications also take bone-building nutrients?

A. Because nutrients work by a different mechanism than osteoporosis drugs, nutritional supplements are likely to enhance the beneficial effect of these medications. Calcium or other minerals may interfere with the absorption of biphophonates such as alendronate (Fosamax) or etidronate (Didronel). For that reason, calcium and other minerals should be taken at least two hours before or two hours after these medications. Also, it is always best to discuss the supplements you are using with your healthcare practitioner to create an integrated health plan.

Final thoughts…

Bone health ramifications extend beyond osteoporosis and fractures. Bone health is essential for freedom of movement, safety, comfort, independence and longevity. Weak bones do not heal well – sometimes they never heal at all. Osteoporosis-related fractures rob us of our mobility and consign thousands of Americans to walkers and wheelchairs every year. In fact, 40% of people are unable to walk independently after a hip fracture, and 60% still require assistance a year later. The most terrible consequence of fractures related to osteoporosis is mortality. The impairment of the ability to move around freely can cause pneumonia and skin damage leading to serious infections. It is estimated that suffering a hip fracture increases the risk of dying almost 25%. Making bone health a priority now will allow you to reap health dividends for many years to come.