Vitamin D: how much to take, when and which kind to choose
Vitamin D is one of the most popular supplements, especially in autumn and winter. The body produces it in the skin when exposed to sunlight, but in the dark months of the year there is often not enough sun.
In this article you will learn how much vitamin D you need per day, how to choose a supplement and how to stay within the safe limit.
In brief. Vitamin D contributes to the maintenance of normal bones, normal muscle function and the normal function of the immune system.1 For adults, about 15 µg (600 IU) per day is sufficient if little sunlight is received.2 The safe upper limit for adults is 100 µg (4,000 IU) per day.3 Choose vitamin D3 and take it with a meal.
What is vitamin D needed for?
Vitamin D1
- contributes to the normal absorption/utilisation of calcium and phosphorus;
- contributes to the maintenance of normal bones and teeth;
- contributes to the maintenance of normal muscle function;
- contributes to the normal function of the immune system.
When is sunlight not enough?
How much vitamin D is produced in the skin depends on the time of year, the time of day, your skin colour and how much time you spend outdoors. For example, the UK health service states that from October to early March the sun is too weak, so vitamin D needs to be obtained from food or supplements.4
A supplement is especially relevant if you rarely go outdoors, cover most of your body, have dark skin or live in a care home.4
How much vitamin D should you take per day?
| Indicator | What the sources say | What this means for you |
|---|---|---|
| Adequate intake for adults | 15 µg (600 IU) per day, including pregnant and breastfeeding women.2 | This is sufficient if you get little sunlight. |
| Children aged 1 year and over | 15 µg per day.2 | Discuss the dose for infants and children with a paediatrician. |
| Upper limit for adults and adolescents aged 11–17 | 100 µg (4,000 IU) per day.3 | Vitamin D from all supplements combined is counted. |
| Upper limit for children aged 1–10 | 50 µg (2,000 IU) per day.3 | Adult supplements are often too strong for children. |
Example. 1 µg of vitamin D equals 40 IU (international units).4 So 25 µg = 1,000 IU, and 50 µg = 2,000 IU. The % NRV shown on EU labels is calculated from 5 µg, so a 25 µg supplement shows 500% NRV.5 This does not mean the dose is dangerous – what matters is whether the 100 µg limit is exceeded.
Which foods contain vitamin D?
Vitamin D is found in oily fish (salmon, sardines, mackerel), egg yolk, liver and fortified foods.4 However, it is difficult to get from food alone, so in winter many people have to choose a supplement.
Which vitamin D supplement should you choose?
| Choice | What is worth knowing | What this means for you |
|---|---|---|
| D3 or D2 | D3 (cholecalciferol) raises blood vitamin D levels more effectively than D2.6 | Choose D3. |
| Capsules, drops, spray | All forms are suitable if taken regularly. | Drops and sprays are convenient if you find it hard to swallow a capsule. |
| For vegans | D3 is most often made from lanolin (sheep's wool fat). | Look for D3 from lichen labelled "vegan". |
| With vitamin K2 | Often combined in one product. | If you take blood-thinning medicines, discuss K2 with your doctor. |
Vitamin D is fat-soluble, so it is convenient to take it with a meal.
Is it possible to overdose on vitamin D?
Yes. Taking too much for a long time causes calcium to build up in the body. This can harm the bones, kidneys and heart.4 It is almost impossible to overdose from food or sunlight – the risk arises when taking high-dose supplements.
Talk to your doctor first if:
- you have kidney disease or have been found to have a high blood calcium level;
- you take other medicines or several supplements containing vitamin D;
- you want to take more than 100 µg per day – this is done only when prescribed by a doctor;
- you want to give a supplement to a child.
The level of vitamin D in the blood can be determined by a test. A supplement is not a substitute for a varied diet.7
Selected vitamin D products
Commercial information. The products shown here are available in our shop. This is not a ranking of effectiveness. Before buying, check the composition and directions for use on the product page.
Vitamin D-3 Liquid, 1000 IU (Extra Strength) - 30 ml - NOW Foods
Vitamin D3 drops, 25 µg (1,000 IU) per drop. The manufacturer recommends 1 drop 1–2 times per day. The pack lasts a long time.8
Vitamin D-3, 2000 IU - 240 softgels - NOW Foods
Vitamin D3 from lanolin, 50 µg (2,000 IU) per capsule, taken as 1 capsule per day with a meal. Not suitable for vegans.9
D1000 Daily Vitamin D Oral Spray - 15 ml - BetterYou
Oral spray, 25 µg (1,000 IU) of vitamin D3 per spray, mint flavour. Contains xylitol, which in larger amounts may have a laxative effect.10
Vitamin D-3 & K-2 - 120 vcaps - NOW Foods
Each capsule contains 25 µg (1,000 IU) of vitamin D3 and 45 µg of vitamin K2 (MK-4). If you take blood-thinning medicines, talk to your doctor first.11
Frequently asked questions
Do you need to take vitamin D in summer too?
For many people, summer sunlight is sufficient. However, if you rarely go outdoors or always cover your skin, you may need vitamin D all year round.4
When is the best time to take vitamin D?
The timing is not important; regularity matters most. It is most convenient to take it with a meal containing fat, for example at breakfast or lunch.
Is 4,000 IU per day safe?
4,000 IU (100 µg) is the safe upper limit for adults.3 Such a dose is usually not needed without a doctor's recommendation. For most people, about 600 IU (15 µg) per day is sufficient.2
Scientific sources
- Komisijos reglamentas (ES) Nr. 432/2012, kuriuo nustatomas leidžiamų teiginių apie maisto produktų sveikatingumą sąrašas (konsoliduota redakcija). EUR-Lex
- EFSA NDA Panel. Dietary reference values for vitamin D. EFSA Journal. 2016;14(10):4547. doi:10.2903/j.efsa.2016.4547
- EFSA NDA Panel. Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate. EFSA Journal. 2023;21(8):8145. doi:10.2903/j.efsa.2023.8145
- NHS. Vitamin D. nhs.uk
- Reglamentas (ES) Nr. 1169/2011 dėl informacijos apie maistą teikimo vartotojams, XIII priedas. EUR-Lex
- Tripkovic L, Lambert H, Hart K et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr. 2012;95(6):1357–1364. doi:10.3945/ajcn.111.031070
- Direktyva 2002/46/EB dėl valstybių narių įstatymų, susijusių su maisto papildais, suderinimo. EUR-Lex
- NOW Foods. Vitamin D-3 Liquid, 1000 IU, 30 ml. Product label.
- NOW Foods. Vitamin D-3, 2000 IU, 240 capsules. Product label.
- BetterYou. D1000 Daily Vitamin D Oral Spray, 15 ml. Product label.
- NOW Foods. Vitamin D-3 & K-2, 120 capsules. Product label.
Disclaimer. This article is for information purposes only and does not replace a consultation with a doctor or pharmacist. Food supplements are not intended to treat or prevent diseases and are not a substitute for a varied diet and a healthy lifestyle. Before taking supplements, especially during pregnancy or breastfeeding, if you have a chronic condition or take medicines, consult a healthcare professional.
