Vitamin D for Bones, Teeth and Muscle Function
Executive Summary
The best-established role of vitamin D: calcium absorption, bone maintenance and normal muscle function — and how calcium fits alongside it.
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Bone health is where the evidence for vitamin DClinical is strongest. Authorised health claims state that vitamin DClinical contributes to the normal absorption and utilisation of calcium and phosphorus, to normal blood calcium levels, to the maintenance of normal bones and teeth, and to the maintenance of normal muscle function.
How it works
Vitamin D increases the efficiency of calcium absorption from the gut. Without enough, the body absorbs less dietary calcium and draws on skeletal reserves to keep blood calcium stable, which over time affects bone mineralisation. Severe, prolonged deficiency causes rickets in children and osteomalacia in adults — both recognised medical conditions requiring diagnosis and treatment.
Calcium and vitamin D together
Vitamin D and calcium are complementary. The UK reference nutrient intake for calcium is 700 mg a day for adults, mostly from dairy foods, fortified plant drinks, tinned fish with bones, tofu set with calcium, and leafy greens. Combined calcium and vitamin D supplements are prescribed in some circumstances — for example alongside certain treatments for osteoporosis — which is a clinical decision.
Taking large amounts of vitamin D and calcium together for a long period can raise blood calcium. Keep within recommended limits and tell your GP or pharmacist everything you take.
Muscle function and falls
Vitamin DClinical contributes to the maintenance of normal muscle function, and severe deficiency can cause proximal muscle weakness. Trials of supplementation for falls prevention in older adults have been mixed, and some high-dose intermittent regimens have shown no benefit or possible harm. UK falls prevention guidance centres on strength and balance exercise, medication review, vision and home hazards — vitamin DClinical is considered as part of a wider assessment, not a standalone answer.
Practical points
- Aim for the recommended 10 micrograms (400 IU) of vitamin D daily, year-round if you are in an at-risk group.
- Meet calcium needs from food where you can.
- Include weight-bearing and resistance exercise, which acts directly on bone and muscle.
- If you have had a fragility fracture, or you have osteoporosis or a family history of it, ask for an assessment rather than self-managing with supplements.
When to ask for advice
Talk to your GP if you have bone pain, muscle weakness, repeated falls or a fracture after a minor injury, or if you have been advised to take calcium and vitamin D together and are unsure of the amounts.
Related reading
- Vitamin D: a UK evidence-based guide
- Vitamin D deficiency symptoms
- Vitamin D side effects and interactions
References and further reading
- Great Britain nutrition and health claims register — GOV.UK. https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register (accessed 26 August 2026)
- Osteoporosis — prevention of fragility fractures — NICE Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/osteoporosis-prevention-of-fragility-fractures/ (accessed 26 August 2026)
- Rickets and osteomalacia — NHS. https://www.nhs.uk/conditions/rickets-and-osteomalacia/ (accessed 26 August 2026)
- SACN vitamin D and health report — GOV.UK. https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report (accessed 26 August 2026)
Article sources
Our editorial team references guidance from independent public health bodies and peer-reviewed research. Links open in a new tab.
- Vitamin D — Health Professional Fact Sheet — NIH Office of Dietary Supplements
- Vitamin D — NHS
- Vitamin D: Is more always better? — Mayo Clinic
- Vitamins and minerals overview — NHS
- Dietary Supplement Fact Sheets — NIH Office of Dietary Supplements
- Healthy Lifestyle — Mayo Clinic
How we reviewed this article
- Medical reviewer
- Prof MM Althaf, MD, FRCP(UK), FASN, MSc.
- Last reviewed
- 26 August 2026
- Next review due
- 26 August 2027
Written by the Vitamin Vitality editorial team from independent public-health guidance and peer-reviewed research, then checked by our medical reviewer. Articles are re-checked at least every 12 months, or sooner when guidance changes. Read our editorial & medical review policy.
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