Vitamin D
cholekalcyferol (D3) · last AI check: 2026-07-19
In short
Made in the skin under sunlight and also supplied through the diet. Its availability is often lower in winter.
What it does in the body
The sentences below are officially authorised EU health claims.
Vitamin D contributes to normal absorption/utilisation of calcium and phosphorus EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 152, 157, 215 · EFSA opinion: 2009;7(9):1227
Condition of use on a product: The product is at least a source of Vitamin D.
Vitamin D contributes to the maintenance of normal bones EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 150, 151, 158 · EFSA opinion: 2009;7(9):1227
Condition of use on a product: The product is at least a source of Vitamin D.
Vitamin D contributes to the normal function of the immune system EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 154, 159 · EFSA opinion: 2010;8(2):1468
Condition of use on a product: The product is at least a source of Vitamin D.
How much you need
| Country / organisation | Group | Value | Type |
|---|---|---|---|
| EFSA | adults | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| FAO | adult men up to 50 | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. | |
| Philippines | adults | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| India | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Japan | adults | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| Poland | adults | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| Singapore | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Switzerland | adults | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| United Kingdom | adults | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. |
Reference values from different countries are not directly comparable — they differ in definition and age group. How to read reference values →
Every value states its source — click it to see the document, location and link.Data and content are prepared and cross-checked against source documents by several independent AI models. They have not been audited by a human editor.Before citing a value, check it in the source document — verification is automated (AI), not editorial.
Worth knowing
Vitamin D is an unusual case in this encyclopaedia for two reasons. First, it is the only one formed in the body under the influence of an external factor that isn't food — UVB radiation reaching the skin. Second, its production depends on latitude: the further from the equator, the longer the part of the year during which the sun sits too low for synthesis in the skin to occur at all. At latitudes such as Central and Northern Europe, this affects a large part of the year, which is why diet and possible supplementation become more important then than in summer.
This explains why reference values for vitamin D tend to diverge particularly sharply between countries — organisations make different assumptions about how much vitamin the sun provides. Notice in the table above that some values are recommended intakes and others are adequate intakes, set when the data don't allow a requirement to be established. These aren't figures of the same kind — more on this in Reading reference values correctly.
How levels are checked
The marker used in clinical practice is serum 25(OH)D concentration, the metabolite formed in the liver. It is convenient because it reflects total intake from sun and diet combined and stays in the blood much longer than the vitamin itself. However, the interpretive thresholds for this test vary between guidelines, and the test itself isn't routinely recommended for everyone — whether it is warranted, and how to interpret the result, is for a doctor to decide.
A note on dosing
Vitamin D is fat-soluble and is stored in the body, so — unlike water-soluble vitamins — any excess isn't simply excreted. This is why a tolerable upper intake level has been set for vitamin D, and supplementing with high doses isn't risk-free. Make that decision, especially for children, pregnant women and older people, together with a doctor, not on the basis of a reference table.
Where to find it
oily fish · egg yolks · fortified foods
This material is for information and education. It does not replace advice from a doctor or dietitian. For health matters, consult a qualified medical professional.