We all probably know someone who can predict the weather by the way their bones and joints feel. And, when someone is especially committed to someone or something, they often say they “feel it in their bones”. But we now have mounting scientific evidence linking the health of your bones to your risk of developing cardiovascular disease (CVD).[i]
Globally, cardiovascular disease is the leading cause of death. It is also the number one killer of Americans; killing more than the next 5 leading causes combined. CVD is responsible for more than a third of all deaths in the United States, and is expected to cost our healthcare system over $500 billion this year.[ii] The majority of cardiovascular events are the result of atherosclerosis. Dysfunction of the endothelium, or vascular lining, is thought to be the earliest step in the process of developing atherosclerosis.[iii] It has been observed in people with coronary atherosclerosis and in people with risk factors for CVD.[iv] Therefore, a healthy endothelium is essential in preventing atherosclerosis. Recent research has identified emerging risk factors that better assess endothelial function, such as arterial stiffness, carotid intima media thickness, and pulse wave velocity.
Osteoporosis is a disorder of normal bone metabolism. Healthy bone results from a lifelong coordinated remolding process of bone resorption and formation that renews the skeleton while maintaining its structure. Approximately 10 million Americans have osteoporosis and another 34 million are at increased risk due to low bone density, or osteopenia. The vast majority (80%) of individuals with osteoporosis are women, with 1 out of every 2 women suffering a fracture due to the disease. But there are also 2 million men with osteoporosis. The risks for men over age 50 are underappreciated with 1 out of every 3.5 of them experiencing a fracture due to osteoporosis.[v] The mortality rate for an individual with osteoporosis following a hip fracture approaches 20% in the first year, and is twice as high for men compared to women.
For both men and women, their risks of developing osteoporosis increases with age and declining hormone levels. Estrogen deficiency in menopause is a major cause of osteoporosis in women. Estrogen acts to maintain the appropriate ratio between bone-forming cells (osteoblasts) and bone-resorbing cells (osteoclasts). Testosterone deficiency in aging men (andropause) is the leading cause of osteoporosis in men. Testosterone directly stimulates the bone-forming cells[vi] and inhibits the formation of bone-resorbing cells.[vii] These hormones act in concert with cytokines (chemical messengers) to control effects of the bone-resorbing osteoclasts.
Cardiovascular disease and osteoporosis are both major health problems in the United States. Although traditionally viewed as separate disease entities a growing body of literature has revealed an association between CVD and osteoporosis. In addition to declining hormones and advancing age, other risk factors for CVD such as dyslipidemia, oxidative stress, inflammation, smoking, hypertension, and diabetes have also been associated with increased risk of low bone mineral density. Elevated LDL and low HDL cholesterol are associated with low bone density. Altered lipid metabolism is associated with both bone remodeling and the atherosclerotic process, which might explain, in part, the co-existence of osteoporosis and atherosclerosis in patients with abnormal lipid profiles. Similarly, inflammation plays a pivotal role in both atherosclerosis and osteoporosis.[viii] As bone mineral density decreases, coronary and aortic vascular calcifications increases.[ix] And, in groups known to exhibit marked endothelial dysfunction, such as diabetics, accelerated bone loss is common.[x] Investigations with post-menopausal women have observed a 1- 4 fold increase in cardiovascular death in women with osteoporosis.[xi] [xii]
Preventing osteoporosis and cardiovascular disease is preferable to treating them. Eating a healthy diet including fruits, vegetables and adequate protein, along with sufficient intake of anti-oxidants, vitamin D, calcium, magnesium and vitamin K is essential. Regular resistance and weight bearing exercises increase androgen (testosterone) levels, muscle strength, and bone mass. Avoid excess alcohol consumption and smoking. Maintain optimal hormone balance and consider early screening to look for evidence of bone loss or altered bone metabolism. Anyone with osteoporosis or osteopenia should have a thorough cardiovascular evaluation looking for evidence of atherosclerosis, increased arterial stiffness or endothelial dysfunction. Being proactive can reduce your risk of dying prematurely or suffering the debilitating consequences of these preventable diseases.
[i] National Institutes of Health – National Heart Lung and Blood Institute Working Group, Sept 1999
[ii] Heart Disease and Stroke Statistics. American Heart Association, 2010 update
[iii] Grey E, Bratelli C, et al. Reduced small artery but not large artery elasticity is an independent risk marker for cardiovascular events. Am J Hypertens, 2003. 16: 265-9
[iv] Anderson TJ. Nitric oxide, atherosclerosis and the relevance of endothelial dysfunction. Heart Fail Rev, 2003. 8:71-86
[v] National Osteoporosis Foundation statistics, www.nof.org
[vi] Chen Q, Kaji H, et al. Testosterone stimulates osteoprotegrin mRNA expressionin mouse osteoblast cells. Horm Metab Res 2004; 36(10): 674-678
[vii] Chen Q, Kaji H, et al. Testosterone inhibits osteoclast formation by parathyroid hormone through androgen receptor. FEBS Lett, 2001. 491: 91-3.
[viii] Koh JM, Kyang YH, et al. Higher circulating hsCRP levels are associated with lower bone mineral density in healthy pre- and postmenopausal women: evidence for a link between systemic inflammation and osteoporosis. Ostoeposrosis Int. October 2005. 16, 10:1263-71
[ix] Barengolts EI, Berman M, Kukreja SC, et al. Osteoporosis and coronary atherosclerosis in asymptomatic postmenopausal women. Calcif Tissue Int, 1998. 62:2013
[x] Schwartz AV, Sellmeyer DE, et al. Diabetes and bone loss at the hip in older black and white adults. J Bone Miner Res. 205, 20:596-603
[xi] Tanko LB, Christiansen C, Cox DA, et al. Relationship between osteoporosis and cardiovascular disease in postmenopausal women. J Bone Miner Res. 2005, 20:1912-20
[xii] Kado DM, Browner WS, Blackwell T, et al. Rate of bone loss is associated with mortality in older women: a prospective study. J Bone Miner Res. 2000, 15:1974-80