Among the most underappreciated threats to longevity in older adults is osteoporosis - the progressive loss of bone density that makes fractures increasingly likely with age.

Hip fractures are the most consequential. Approximately 300,000 Americans suffer a hip fracture each year, the majority of them over 65. The statistics that follow are sobering: 20-30% of hip fracture patients die within one year. Half of those who survive never regain their prior level of function. A third require long-term care.

These are not outcomes of a rare disease. They are outcomes of a process - bone aging - that begins in the fourth decade of life and accelerates dramatically after menopause in women and more gradually in men.

Bone is not static tissue. It is continuously remodeled throughout life through the coordinated activity of two cell types: osteoblasts, which build new bone, and osteoclasts, which break down old bone. In youth, this process favors formation. With age, the balance shifts toward resorption.

Peak bone mass is achieved in the late 20s to early 30s. The amount of bone you accumulate by this point is one of the most important determinants of your fracture risk decades later. Higher peak bone mass provides a larger reserve against age-related loss.

The perimenopausal transition is the most dramatic period of bone loss in women. In the 5-7 years around menopause, estrogen withdrawal accelerates osteoclast activity dramatically. Women can lose 2-3% of bone density per year during this period - compared to 0.5-1% per year before and after. Over the perimenopausal decade, total bone loss can reach 20-30%.

Male bone loss is more gradual, driven primarily by declining testosterone and IGF-1. Men lose bone at approximately 0.5-1% per year starting in their 40s, accelerating somewhat after 70.

Secondary causes of bone loss are common and often overlooked: vitamin D deficiency, calcium inadequacy, glucocorticoid use, thyroid disorders, inflammatory conditions, and certain medications all accelerate bone loss beyond the normal age-related trajectory.

The consequences of osteoporosis extend beyond the obvious fracture risk.

Vertebral fractures - compression fractures of the spine - are the most common osteoporotic fractures and are often painless. They cause progressive height loss, kyphosis (the stooped posture associated with aging), and chronic back pain. They also compress the thoracic cavity, reducing lung capacity and contributing to respiratory decline.

Wrist fractures (Colles fractures) are common in falls and, while rarely fatal, often signal the beginning of a fracture cascade and are associated with subsequent hip fracture risk.

The fall-fracture cycle. Osteoporosis and sarcopenia (muscle loss) frequently coexist and reinforce each other. Muscle weakness increases fall risk; falls cause fractures; fractures cause immobility; immobility accelerates both muscle and bone loss.

Bone density is measured by dual-energy X-ray absorptiometry (DEXA), which provides a T-score comparing your bone density to that of a healthy young adult. A T-score below -1.0 indicates osteopenia; below -2.5 indicates osteoporosis.

The FRAX tool (Fracture Risk Assessment Tool) integrates bone density with clinical risk factors to estimate 10-year fracture probability. It is more clinically useful than T-score alone because it accounts for age, sex, weight, prior fractures, family history, smoking, alcohol use, and glucocorticoid use.

Current guidelines recommend DEXA screening for all women 65 and older, and for younger postmenopausal women with risk factors. Men should be screened at 70, or earlier with risk factors.

Resistance training. Mechanical loading is the most potent stimulus for bone formation. Osteoblasts respond to the stress placed on bone by increasing bone formation. Resistance training - particularly exercises that load the spine and hips - is the most evidence-backed non-pharmacological intervention for maintaining bone density. Studies consistently show that resistance training maintains or modestly increases bone density in older adults, while sedentary behavior accelerates loss.

Impact exercise. High-impact activities - running, jumping, tennis, dancing - provide bone-loading stimuli that low-impact activities do not. Even brief periods of high-impact activity (jumping 10-20 times per day) have been shown to improve bone density in postmenopausal women.

Adequate calcium. Calcium is the primary mineral in bone. Adequate intake (1000-1200mg/day for adults over 50) is necessary for bone maintenance. Food sources are preferable to supplements - dairy, leafy greens, fortified foods. Calcium supplements above 500mg at a time are poorly absorbed and may have cardiovascular risks that food sources do not.

Vitamin D. Vitamin D is essential for calcium absorption and bone mineralization. Deficiency is extremely common, particularly in northern latitudes and in older adults who spend less time outdoors. Most adults benefit from 1000-2000 IU/day of vitamin D3, with levels targeted to 40-60 ng/mL (100-150 nmol/L).

Protein. Adequate protein intake supports bone matrix formation and muscle mass, which in turn supports bone through mechanical loading. Higher protein intake is associated with better bone density in older adults - the concern that protein acidifies the body and leaches calcium from bone has not been supported by clinical evidence.

Estrogen therapy. Hormone replacement therapy is the most effective intervention for preventing perimenopausal bone loss. The timing hypothesis - initiating HRT close to menopause rather than years later - suggests that early initiation provides the greatest bone and cardiovascular benefit with the lowest risk. This is a decision that requires individualized discussion with a physician.

Pharmacological options. For established osteoporosis or high fracture risk, several drug classes are effective: bisphosphonates (alendronate, risedronate) reduce fracture risk by 40-70%; denosumab (a RANK-L inhibitor) is effective in postmenopausal women and men on androgen deprivation therapy; romosozumab and teriparatide are anabolic agents that actually build new bone rather than just slowing resorption.

Fracture risk is the product of bone strength and fall risk. Reducing falls is as important as maintaining bone density.

Balance training. Tai chi, yoga, and specific balance exercises reduce fall risk in older adults. The evidence for tai chi is particularly strong - multiple randomized trials have shown 40-50% reductions in fall rates.

Home hazard modification. Removing trip hazards, improving lighting, installing grab bars, and using non-slip mats in bathrooms reduces fall risk substantially.

Medication review. Many common medications increase fall risk: sedatives, antidepressants, antihypertensives, and diuretics all contribute. Regular medication review with a physician is important for older adults.

Vision correction. Uncorrected vision impairment is a significant fall risk factor. Regular eye examinations and appropriate correction are important.

The most important message about bone health is that the time to act is before bone loss becomes significant - ideally in the 30s and 40s, when peak bone mass can still be optimized, and certainly in the 50s, when perimenopausal loss begins.

By the time a fracture occurs, significant bone loss has already happened. The goal is to never reach that point - through adequate calcium and vitamin D, regular resistance and impact exercise, and appropriate screening and treatment when indicated.

Bone health is not a separate concern from longevity. It is one of the most direct determinants of whether you remain independent, mobile, and functional in your later decades.