How Much Vitamin D Do You Need? UK Guidance on Daily Doses
Executive Summary
UK recommended intakes by age, how micrograms convert to IU, safe upper limits, and where higher-strength supplements fit.
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UK guidance recommends 10 micrograms (400 IU) of vitamin DClinical a day for everyone aged 1 and over — considered by everyone in autumn and winter, and taken year-round by people at higher risk of low vitamin DClinical. Babies under 1 need 8.5 to 10 micrograms a day unless they have more than 500 ml of infant formula daily.
Micrograms and IU: the conversion
Labels use both units. The conversion is fixed:
| Micrograms (µg) | International units (IU) |
|---|---|
| 10 µg | 400 IU |
| 25 µg | 1,000 IU |
| 50 µg | 2,000 IU |
| 75 µg | 3,000 IU |
| 100 µg | 4,000 IU |
The EU/GB Nutrient Reference Value for vitamin D is 5 micrograms, which is why a 10 microgram product shows 200% NRV. That is a labelling reference figure, not a maximum.
UK recommended intakes by age
- Adults and children aged 1 and over: 10 micrograms (400 IU) daily.
- Babies from birth to 1 year: 8.5 to 10 micrograms daily, unless having more than 500 ml of fortified infant formula per day.
- Pregnancy and breastfeeding: 10 micrograms daily; Healthy Start vitamins may be available.
Safe upper limits
The NHS advises daily amounts should not exceed:
- Adults, including pregnant and breastfeeding women, and children aged 11 to 17: 100 micrograms (4,000 IU)
- Children aged 1 to 10: 50 micrograms (2,000 IU)
- Infants under 12 months: 25 micrograms (1,000 IU)
These upper limits describe amounts unlikely to cause harm in the general population over time. They are not targets. A clinician may prescribe more than the upper limit for a defined period to correct diagnosed deficiency, with monitoring.
Where higher-strength products fit
Products supplying 1,000 to 4,000 IU are widely sold in the UK. A higher-strength product is not automatically better. It suits some adults — for example those advised to supplement year-round who prefer a single small daily tablet — and does not suit others, including children, and people with conditions affecting calcium handling. We look at this in detail in Is 4,000 IU vitamin D safe?
Before choosing a higher strength, add up everything you take. Multivitamins, cod liver oil, fortified drinks and calcium-and-vitamin-D products all contribute.
When to ask for individual advice
Speak to a GP or pharmacist before exceeding 10 micrograms daily if you have kidney disease, a history of kidney stones, sarcoidosis, hyperparathyroidism or raised blood calcium, if you take thiazide diuretics or digoxin, if you are pregnant or breastfeeding, or if the supplement is for a child.
Related reading
- Vitamin D: a UK evidence-based guide
- Is 4,000 IU vitamin D safe?
- Can you take vitamin D every day?
- Vitamin D side effects and interactions
References and further reading
- Vitamin DClinical — NHS. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ (accessed 26 August 2026)
- SACN vitamin DClinical and health report — GOV.UK. https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report (accessed 26 August 2026)
- Vitamin D deficiency in adults — NICE Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/vitamin-d-deficiency-in-adults/ (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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