Bone Health — Calcium, Vitamin D & the Silent Risk of Osteoporosis
IOF Osteoporosis Clinical Guidelines & ICMR Calcium Recommendation Reports
Educational content only. This information is for general awareness and does not constitute medical advice. Please consult a qualified healthcare provider for any medical concerns or before making health decisions.
Key Facts
~61 million
Indians with osteoporosis
Including both men and women — one of world's highest burdens
20–30%
Hip fracture mortality (1 year)
One in four elderly people die within a year of a hip fracture
< 30%
Urban Indians meeting calcium RDA
Most get less than half the recommended 1000 mg/day
25–30
Bone mass peak age
After this, net bone density slowly declines — prevention must start early
How Bones Work — and Why They Fail Silently
Bone is not static — it is continuously being broken down by cells called osteoclasts and rebuilt by osteoblasts. This cycle, called bone remodelling, is regulated by hormones (PTH, oestrogen, testosterone, calcitonin) and nutrients (calcium, Vitamin D, Vitamin K2, magnesium).
Osteoporosis — literally 'porous bone' — occurs when breakdown outpaces formation. It is completely silent until a fracture occurs. The wrist, vertebrae, and hip are most commonly affected, and hip fractures in the elderly carry a 20–30% mortality rate in the first year.
The good news: bone density loss can be detected early through blood markers and DEXA scans, and progression can be significantly slowed.
Blood Markers for Bone Health
Serum Calcium:: Total calcium in blood is tightly regulated. Both hypercalcaemia (too high) and hypocalcaemia (too low) cause serious symptoms. Normal: 8.5–10.5 mg/dL.
Serum Phosphorus:: Works with calcium in bone mineralisation. Low phosphorus + low calcium suggests nutritional deficiency. Normal: 2.5–4.5 mg/dL.
PTH (Parathyroid Hormone):: The master regulator of calcium. High PTH (hyperparathyroidism) causes calcium to be leached from bones to raise blood levels — leading to bone weakening. Low PTH causes hypocalcaemia.
Vitamin D (25-OH):: Essential for calcium absorption in the gut. Without adequate Vitamin D, dietary calcium is poorly absorbed regardless of intake. Normal: 30–100 ng/mL.
Bone Turnover Markers::
• **Beta-CrossLaps (β-CTX):** Measures bone breakdown rate — elevated in active osteoporosis
• **Osteocalcin / P1NP:** Measures new bone formation
These markers, combined with DEXA scan (measures actual bone mineral density), give a complete bone health picture.
Calcium — The Numbers That Surprise Most People
Daily calcium requirements::
• Adults 19–50: 1000 mg/day
• Women over 50 / Men over 70: 1200 mg/day
• Pregnant and breastfeeding women: 1000–1300 mg/day
A glass of full-fat milk contains ~300 mg calcium.: To meet the daily requirement from milk alone, you'd need ~3 glasses — which most urban Indians don't consume.
Food calcium myth:: Serum calcium levels appear normal even in calcium-deficient individuals because PTH constantly pulls calcium from bones to maintain blood levels. A normal serum calcium does NOT mean your bones are adequately calcified. The PTH-Calcium-Vitamin D triangle together gives the real picture.
Calcium supplements:: Should be taken with Vitamin D3 for absorption. Calcium carbonate needs stomach acid; calcium citrate does not — important for those on acid-suppressing medications.
Who Is at Highest Risk and Who Should Be Tested?
High-risk groups::
• Postmenopausal women (oestrogen fall accelerates bone loss sharply)
• Men over 65
• Anyone with low Vitamin D (extremely common in India)
• People on long-term steroids (prednisolone, dexamethasone)
• Individuals with thyroid disorders, malabsorption conditions (coeliac, IBD)
• Those with a family history of osteoporosis or early fractures
• Very thin individuals (low body weight = less bone-stimulating load)
Testing recommendations::
• Serum calcium + phosphorus + Vitamin D: Annual for adults over 40
• PTH: Add if calcium is abnormal or Vitamin D is very low
• DEXA scan: Baseline for all women at menopause; every 2 years if at risk
Related Insights
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