Bone that has lost enough density and structure to break under a force that should not break it. The diagnosis is made on a scan, but the thing that matters is a fracture, and the nutrition evidence here contains a genuine surprise: more vitamin D is not better, and given in the wrong way it did harm3.
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A skeletal condition of reduced bone mass and deteriorated bone structure, which together raise the risk that a bone breaks. Formally it is diagnosed when bone density on a scan sits far enough below a young adult reference, or when a fragility fracture has already happened.
Bone is not inert scaffolding. It is remodeled continuously, broken down by one cell population and rebuilt by another, and the balance between the two shifts across a lifetime. Peak bone mass is reached in the twenties. After that the balance tips slowly, and around menopause it tips sharply for several years as estrogen falls, which is why the condition is so much more common in women.
The distinction that matters most for reading anything about osteoporosis: bone density is a measurement, and fracture is the outcome. An intervention can improve the measurement without preventing a single break. Several of the findings below are exactly that case, which is why this page keeps asking what happened to fractures rather than what happened to the scan.
The old idea that dietary protein leaches calcium from bone did not survive testing. A systematic review for the National Osteoporosis Foundation found higher protein intake was not harmful to bone, and may modestly help at the lumbar spine7.
Bone adapts to the forces put through it. A Cochrane review of exercise in postmenopausal women found a small but statistically significant effect on bone density, with combination programs performing best6.
Almost every hip fracture involves a fall13. Strength, balance, vision, footwear, home hazards and sedating medication are part of fracture prevention, and no amount of calcium substitutes for them.
It has no symptoms at all until a bone breaks, which is the whole problem. These are the things that identify risk before that happens.
| Sign or risk factor | What it means |
|---|---|
| A fracture from a fall at standing height or less | A fragility fracture, which by itself can establish the diagnosis. Worth knowing: The single strongest predictor of the next fracture, and frequently not followed up. |
| Height loss, or a stooped upper back | Possible vertebral fractures, which often happen without any recognized event. Worth knowing: Most vertebral fractures are never diagnosed at the time. |
| Sudden mid-back pain in an older adult | May be a vertebral fracture. Worth knowing: New severe back pain deserves assessment rather than being attributed to age. |
| Early menopause, or primary ovarian insufficiency | A longer period of life without estrogen's protective effect on bone. Worth knowing: See menopause and premature ovarian insufficiency. |
| Long-term oral corticosteroid use | One of the most important causes of secondary osteoporosis. Worth knowing: Bone protection is often indicated alongside; a prescriber question, never a reason to stop the steroid. |
| Celiac disease or other malabsorption | Calcium and vitamin D absorbed poorly for years, sometimes silently. Worth knowing: See celiac disease; unexplained osteoporosis is a recognized reason to test for it. |
| Overactive thyroid, or over-replacement of thyroid hormone | Accelerated bone turnover. Worth knowing: See thyroid disorders; worth reviewing the dose with your prescriber. |
| Low body weight, smoking, heavy alcohol use | Each independently associated with lower bone density and higher fracture risk. Worth knowing: All three are modifiable, and all three also raise falls risk. |
Losing some bone with age is normal; osteoporosis follows when bone is lost faster than usual, and these are the established reasons16.
| Cause | How It Contributes to Osteoporosis | What Helps |
|---|---|---|
| Age and menopause | Bone loss is part of aging, and women lose bone rapidly in the first few years after menopause, especially if it starts before 45 or the ovaries have been removed16 | A fracture-risk assessment and, where risk is high, prescribed bone-strengthening medicine; after an early menopause, ask about hormone treatment17 |
| Long-term steroid tablets | Taking high-dose steroid tablets for more than 3 months raises the risk16 | Bone protection prescribed alongside the steroid; never stop a steroid on your own |
| Malabsorption and hormone conditions | Conditions that stop calcium and vitamin D from being absorbed, hormone-related and inflammatory conditions, and some long-term medicines that affect bone or hormones16 | The celiac, thyroid and medication checks in the diagnosis section, since treating the cause changes the plan |
| Low body weight and eating disorders | A low body mass index, or having had anorexia or bulimia, raises the risk16 | Enough protein and energy, as the diet section describes, with specialist care for an eating disorder |
| Smoking, heavy drinking and inactivity | Each raises the risk16; exercise has a small but real effect on bone density in postmenopausal women6 | Stopping smoking, moderating alcohol, and progressive resistance and weight-bearing exercise, as the treatment section describes |
| Family history | A family history of osteoporosis raises the risk, particularly a parent's hip fracture16 | Nothing to change; tell your clinician so it is weighed in the fracture-risk assessment the diagnosis section describes |
A scan gives a number. A proper assessment asks why the number is what it is, and what the actual fracture risk is.
| Test | What it shows |
|---|---|
| DXA bone density scan | Bone mineral density at hip and spine, and the diagnostic classification. Worth knowing: Says nothing about bone quality or falls risk, and at least half of fractures occur above the osteoporotic threshold12. |
| Fracture risk calculators | Estimated probability of fracture over the next ten years, combining density with clinical risk factors. Worth knowing: Population tools; they do not know about your stairs, your eyesight or your sedating medication. |
| 25-OH-D (vitamin D blood test) | Whether deficiency is present and needs correcting. Worth knowing: A number, not an instruction to take a large dose; a large single yearly dose of vitamin D increased falls and fractures in a trial3. |
| Calcium, phosphate, alkaline phosphatase, kidney function | Screens for other bone and mineral disorders. Worth knowing: Normal results do not exclude poor dietary intake. |
| Celiac serology | A treatable malabsorptive cause that can be silent for years. Worth knowing: Must be done while still eating gluten; see celiac disease. |
| Thyroid function, and review of thyroid hormone dose | Over-replacement accelerates bone loss and is common. Worth knowing: A prescriber conversation; see thyroid disorders. |
| Medication review | Corticosteroids, some anticonvulsants and several other classes affect bone or falls risk. Worth knowing: Requires someone to actually look; it is rarely volunteered. |
| Falls and balance assessment | The other half of fracture risk, and the half most often ignored. Worth knowing: Not part of a DXA report, so it has to be asked for. |
Protein, calcium from food, adequate vitamin D, loading the skeleton and not falling over
Feed the bone and feed the muscle that keeps you off the floor. Those are two jobs, and diet does both.
Protein and calcium for bone, and the muscle that keeps you upright
| What to eat or do | Details |
|---|---|
| Protein | Bone matrix is largely protein, and muscle strength determines whether you fall. Spread across meals rather than concentrated in one. Best food sources: Dairy, eggs, fatty fish, poultry, legumes, nuts. |
| Calcium | The mineral the matrix is filled with. Food sources come with protein and other nutrients that supplements do not. Best food sources: Dairy, canned sardines and wild salmon with bones, kale, bok choy. |
| Vitamin D | Required for calcium absorption. Sufficiency is the goal, not high levels. Test rather than assume. Best food sources: Fatty fish and egg yolk; sunlight also makes vitamin D in the skin. |
| Vitamin K | Needed to carboxylate osteocalcin, a bone matrix protein. See the anticoagulant warning below. Best food sources: Leafy greens for K1; natto, some cheeses and fermented foods for K2. |
| Magnesium | A structural component of bone and involved in vitamin D metabolism. Best food sources: Nuts, seeds, legumes, whole grains, leafy greens. |
| Potassium and fruit and vegetables | Associated with better bone density in observational work. Best food sources: Vegetables and fruit generally; no supplement needed. |
| Sodium, in excess | Raises urinary calcium loss. Practical note: Most dietary sodium comes from processed food, not the saltshaker. |
| Alcohol, in excess | Affects bone-forming cells and substantially raises falls risk. Practical note: The falls effect alone is reason enough to moderate it. |
Taking too much of some of these does harm, so read the cautions.
| Supplement | What it is for | Typical range | Timing | Notes & cautions |
|---|---|---|---|---|
| Vitamin D3 | Correcting a measured deficiency so that calcium is absorbed properly. Not a fracture treatment in people who are already replete. | Test 25-OH-D first and set a daily dose with your clinician | Daily, with a fat-containing meal | Do not take large intermittent doses. An annual high dose increased falls and fractures3 and a monthly high-dose regimen increased falls4. In generally healthy adults supplementation did not reduce fractures at all5. The adult upper intake level is 4,000 IU a day; a dose above it is for your clinician to set when correcting a deficiency. Retest at 3 months. |
| Calcium | Filling a genuine dietary shortfall only, where food cannot realistically reach an adequate intake. | Enough to top up food intake, not a fixed large dose. Divide doses; absorption falls above roughly 500 mg at once | With food, split through the day | Food first, for the cardiovascular question above2. Can cause constipation and bloating. Reduces absorption of thyroid hormone, some antibiotics and iron, so separate them by several hours. Discuss with your clinician if you have had kidney stones or have kidney disease; see chronic kidney disease. |
| Vitamin K2 (MK-7) | Carboxylating osteocalcin. Three years of low-dose MK-7 reduced the loss of bone mineral density in healthy postmenopausal women8. | 100 to 200 mcg per day; the trial above used 180 mcg | With a fat-containing meal | See the anticoagulant warning above; this is the important one. The trial measured bone density and bone strength rather than fractures, so treat it as promising and not as proven fracture prevention. |
| Magnesium | Correcting a shortfall where dietary intake is low. A structural component of bone and involved in vitamin D metabolism. | 200 to 400 mg per day of elemental magnesium if food intake is low | Evening, with food | Citrate and glycinate are better tolerated than oxide. Can loosen stools. Reduce or avoid in reduced kidney function, where magnesium accumulates. The top of this range is above the 350 mg/day upper intake level for supplemental magnesium11; above that, diarrhea is common. With kidney disease, take it only on your clinician's advice. |
Bone changes slowly, and the outcome that counts is fewer fractures; for people at high risk, prescribed medicine does most of that.
After a break from a minor fall, ask for your bone health to be assessed as well as the break treated; a risk calculator and a bone density scan guide what comes next. Removing trip hazards and checking eyesight start now16.
See a doctor after a break from a minor fall, or for sudden severe back pain, loss of height or a stooped posture, which can mean a spine fracture19. On a bone-strengthening medicine, report any thigh, hip or groin pain18, and mention any jaw problems, since a rare jaw bone side effect is linked to these medicines17.
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Bone changes slowly, and the outcome that counts is fewer fractures; for people at high risk, prescribed medicine does most of that. Alongside it, start resistance and balance training, remove trip hazards and have your eyesight checked.
Each numbered entry below is either a source you can follow or a note setting out what the evidence does and does not support. Both are numbered together so the markers in the text line up.
Last reviewed October 20, 2026. Supplement entries are cross-checked against the NIH National Center for Complementary and Integrative Health and the Linus Pauling Institute Micronutrient Information Center.10 This page is nutrition education, not medical advice, and it does not replace your doctor. Nutrition does not treat established osteoporosis on its own. No dietary measure here has been shown to prevent fractures the way prescribed treatment does, and nothing on this page is a reason to decline or stop it. What nutrition education can do is help you understand the evidence well enough to have a better conversation with the clinician who does treat you.