Bones – keeping them strong, and what osteoporosis means

Osteoporosis is a loss of bone density that makes bones fragile. It causes no pain and no symptoms whatsoever until a bone breaks — commonly a wrist, a spine bone or a hip.

Bone is living tissue that is constantly rebuilt. Density peaks in the late twenties and declines slowly afterwards, with a sharper drop in women in the years after menopause when oestrogen falls. What you do in your twenties and thirties sets the peak; what you do later slows the decline.

• Women after menopause, and especially after an early menopause or hysterectomy with ovary removal.
• A parent who had a hip fracture.
• Previously breaking a bone from a minor fall as an adult.
• Long-term steroid tablets — one of the more important and more overlooked causes.
• Smoking and heavy drinking.
• Being underweight, or a history of an eating disorder.
• An overactive thyroid, coeliac disease, rheumatoid arthritis, chronic kidney disease, and long-standing HIV.
• Little physical activity, and very little sun exposure.
• Men too — osteoporosis in men is under-diagnosed because it is thought of as a women's condition.

1. 1Weight-bearing exercise — walking, stair climbing, dancing, jogging. Bone responds to being loaded, so swimming and cycling, while excellent for other things, do less for bone.
2. 2Resistance work twice a week. Muscle pulling on bone is a direct stimulus to keep it.
3. 3Enough calcium: milk, maas, yoghurt, tinned fish with soft bones, and green leafy vegetables. Most South African adults fall well short.
4. 4Enough vitamin D, which is what lets the body absorb calcium. Brief regular sun exposure outside peak hours covers most people here; a supplement is used where a test shows a deficiency.
5. 5Stop smoking, and keep alcohol down. Both directly reduce bone density.
6. 6Prevent falls — see the falls article. Strong bones and not falling are two halves of the same goal.

Bone density is measured by a DXA scan, a short, painless X-ray-based test. It is not offered to everyone — it is used where risk factors, a fracture from a minor fall, or long-term steroid use make it worthwhile. Ask a doctor whether your risk profile warrants it.

Treatment where it is indicated substantially reduces fracture risk. Tablets are typically taken on an empty stomach with a full glass of water, sitting or standing upright for a period afterwards — the instructions are unusually specific and following them matters both for absorption and for avoiding irritation of the gullet.