Bones
What the NHS, NICE and the Royal Osteoporosis Society advise on vitamin D and calcium, and the evidence on vitamin K2, magnesium, boron and collagen, with prices per dose.
The NHS says adults need 700mg of calcium a day, and that everyone should consider a daily 10 microgram vitamin D supplement in autumn and winter. The Royal Osteoporosis Society says a supplement can top up calcium when food falls short. The NHS advises people at risk of osteoporosis, including older people, to avoid supplements containing retinol, a form of vitamin A, including fish liver oil.
Royal Osteoporosis Society: Evidence on nutrient supplements for bones is limited.
Each line below is a short summary of what the named source says, with a link to read it in full. None of it is medical advice.
Advised
Vitamin D
A vitamin the body makes when skin is in sunlight. Oily fish, eggs and fortified foods have some; supplements come as D3 or D2.
- NHS: Hard to get enough from food alone, so consider a daily 10 microgram supplement.
- Royal Osteoporosis Society: Recommended all year if you rarely go outside, cover up, or mostly use sunscreen.
Also covered by NHS (Vitamin D; Food for healthy bones) and British Dietetic Association.
Calcium
A mineral, most of it held in bones and teeth. Milk, cheese, yoghurt, fish eaten with its bones and fortified plant drinks are common sources.
- Royal Osteoporosis Society: If food does not give enough calcium, a supplement can top it up.
- British Dietetic Association: If diet falls short, 400-600mg a day, preferably with 10 micrograms of vitamin D.
Also covered by NHS (Calcium; Food for healthy bones; Osteoporosis - Treatment), NICE and British Dietetic Association.
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Limited evidence
Vitamin K2
A form of vitamin K mostly made by gut bacteria, and found in meat, eggs, soya foods and some cheeses.
- Royal Osteoporosis Society: Evidence on vitamin K supplements for bones isn't strong.
Also covered by Royal Osteoporosis Society and NHS.
Boron
A trace mineral found in green vegetables, avocados, potatoes, fruit, nuts, eggs and milk.
- Royal Osteoporosis Society: Only a few studies on boron and bone health; more research is needed.
Collagen
The most abundant protein in the body. Supplements are made from animal hides, bones or cartilage, or from fish.
- Harvard Health Publishing: Research on collagen supplements is still early; large studies need to confirm any effects.
Magnesium
A mineral found in green vegetables, nuts, wholegrain bread, fish, meat and dairy foods.
- Royal Osteoporosis Society: Routine magnesium supplements have not been proven useful.
Also covered by Royal Osteoporosis Society and NHS.
No good evidence
Isoflavones (phyto-oestrogens)
Plant compounds, also called phyto-oestrogens, found in soya and linseed foods and sold as supplements.
- Royal Osteoporosis Society: Studies found no effect, or at best a very weak one, on bone density.
- Royal Osteoporosis Society: Research has not found that they lower the risk of fragility fractures.
Advised against
Vitamin A and fish liver oil
Vitamin A in its retinol form, found in liver, fish liver oils such as cod liver oil, and many multivitamins.
- NHS: If at risk of osteoporosis, avoid supplements containing retinol, including fish liver oil.
- Royal Osteoporosis Society: Best stopped by anyone who regularly eats foods high in vitamin A.
Also covered by NHS and Royal Osteoporosis Society.
Things to check
- NHS: Do not take more than 100 micrograms (4,000 IU) of vitamin D a day.
- Royal Osteoporosis Society: More than 1,500mg a day of calcium supplements can be bad for health; other supplements may contain calcium too.
- NHS: Women past the menopause and older men should keep vitamin A from food and supplements to 1.5mg a day; many multivitamins contain it.
- Royal Osteoporosis Society: If you take warfarin, do not take a vitamin K supplement without discussing it with your GP first.
- NICE: Calcium supplements can reduce the absorption of bisphosphonates, levothyroxine, iron, zinc and some antibiotics; take them at different times.
- Royal Osteoporosis Society: Some studies found high intakes of copper and zinc from supplements may increase bone loss.
- NHS: More than 400mg of magnesium a day from supplements can cause diarrhoea.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
Sources
- Vitamin DWho should consider a vitamin D supplement, how much, and the most to take in a day.
- Food for healthy bonesCalcium and vitamin D for bones, and the limit on vitamin A for people at risk of osteoporosis.
- Osteoporosis - PreventionLifestyle steps for osteoporosis: exercise, calcium in the diet, vitamin D supplements, sunlight, smoking and alcohol.
- Osteoporosis - TreatmentOsteoporosis medicines, and calcium and vitamin D supplements alongside them.
- CalciumWhere calcium comes from, how much adults need, and how much is safe to take.
- Vitamin KWhere vitamin K comes from, how much adults need, and how much is safe to take.
- Vitamins and minerals - OthersOther minerals, including how much magnesium adults need and how much is safe to take.
- Vitamin AWhere vitamin A comes from, how much adults need, and the limit for older people.
- Osteoporosis - prevention of fragility fractures: Scenario: ManagementNICE's summary for GPs on osteoporosis medicines, and on prescribing calcium and vitamin D with them.
- Osteoporosis - prevention of fragility fractures: Calcium and colecalciferol (vitamin D3) preparationsCautions, side effects and medicine interactions for calcium and vitamin D preparations.
- CalciumHow much calcium adults need, the foods it comes from and when a supplement is used.
- Vitamin D for bonesVitamin D from sunlight, food and supplements, with amounts and an upper limit.
- Other vitamins and minerals for bone healthB vitamins, vitamin C, vitamin K and magnesium, and whether a supplement is needed.
- Further food facts and bones - looking beyond calcium and vitamin DThe charity's fact sheet on other nutrients and bones, including vitamin K, magnesium, boron and phyto-oestrogen supplements.
- Are there any foods I should avoid?Foods to have in moderation, including vitamin A from liver, fish liver oils and multivitamins.
- Osteoporosis and dietCalcium, vitamin D, protein and lifestyle for bones, including calcium supplement amounts.
- CalciumHow much calcium different people need, where it comes from, and topping up with a supplement.
- Do collagen supplements fulfill their promises?A doctor's answer on what the research on collagen supplements does and does not show.
Sources checked 28 September 2026. Prices checked 20 October 2026, ranked purely by price per dose. Which sources these pages use.