Your vitamin D label, explained
Where vitamin D3 comes from, what else is in the capsule, and how to compare two bottles like with like. Plain words, sources at the end.
"Cholecalciferol" just means vitamin D3
That's its chemical name. The label has to tell you it's D3 and how much is in each serving. It doesn't have to tell you what the D3 was made from.
Most vitamin D3 starts with sheep's wool
The usual starting point is lanolin, the natural grease in sheep's wool. It's washed out of the wool after the sheep are sheared.
Wool, lichen, fish oil
Wool (lanolin)
The standard source for D3 in supplements and fortified foods.
Lichen
The flat, grey-green or orange patches you see on rocks and old trees. It isn't a plant or a moss. It's a fungus and a tiny alga living together as one.
Fish liver oil
Cod liver oil contains vitamin D3 naturally, and some products use it.
How to tell which one you have: vegan D3 usually says so, or says "from lichen". If the label says neither, the D3 most likely came from wool.
The D3 is tiny. Most of the capsule is the carrier.
Vitamin D is measured in micrograms, millionths of a gram. So a capsule or tablet is mostly whatever carries it.
Softgel
The D3 is dissolved in an oil, for example soybean oil, olive oil or MCT oil, inside a shell. Shells are often gelatin, which comes from animals. Some brands use plant-based shells.
Tablet or powder
The D3 is made into a dry powder so it can be pressed or filled. One supplier's powder lists, by weight: sucrose, gum arabic, corn starch, MCT oil, tricalcium phosphate, then the D3, then vitamin E to keep it stable.
Look at the "other ingredients" line on your label. That's where the carrier and the shell are listed.
Three things to check on any two labels
- The amount per serving, in micrograms (µg)1 µg = 40 IU. So 25 µg and 1,000 IU are the same amount. Check the serving size too: "2 capsules" means you divide by two to compare per capsule.
- The sourceWool, lichen or fish oil. Only a vegan or lichen claim tells you for sure.
- The carrierOil in a softgel, or a tablet or powder. Read the "other ingredients" line and the shell.
About "% NRV": in the EU the reference amount for vitamin D is 5 µg a day. So "400% NRV" simply means 20 µg. It's a unit conversion, not a quality mark.
Worked example (two made-up labels, for illustration only):
| Label A | Label B | |
|---|---|---|
| Says | 1,000 IU per softgel | 50 µg per 2 tablets |
| Per unit, in µg | 1,000 ÷ 40 = 25 µg | 50 ÷ 2 = 25 µg |
| Source | Not stated, so most likely wool | "Vegan D3 from lichen" |
| Carrier | Olive oil, gelatin shell | Starch, sugar, anti-caking agent |
Same amount of D3 per unit. Different source, different carrier. Now you're comparing like with like.
What this doesn't mean
- Wool-based D3 isn't worse. It's the same molecule as lichen D3.
- Vegan D3 isn't stronger. The source changes the story, not the vitamin.
- This isn't advice to take, stop or change a supplement, or on how much to take. Ask your doctor or pharmacist about that.
- NIH Office of Dietary Supplements: Vitamin D fact sheet (how D3 is made from lanolin; 1 µg = 40 IU)
- FoodUnfolded: How are vitamin D supplements made? (the process step by step; lichen D3)
- Nutritional Outlook: Vegan vitamin D3 from lichen
- BASF: Dry Vitamin D3 100 GFP technical information (example powder composition)
- DailyMed: example vitamin D3 softgel label
- Regulation (EU) No 1169/2011, Annex XIII (vitamin D reference intake: 5 µg)
From Evmara
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