Vitamin D3 vs D2 (Colecalciferol vs Ergocalciferol)
Short answer: Both forms of vitamin D work, but vitamin D3 (colecalciferol) raises blood levels more than D2 (ergocalciferol), especially when given as large, occasional doses. With daily doses the gap is smaller. Most supplements in Australia are D3. D2 comes from plants or fungi; vegan D3 made from lichen is also available.
Vitamin D3 (colecalciferol)
- The form your skin makes in sunlight
- Found in oily fish and eggs
- Usually made from lanolin (sheep’s wool); vegan versions from lichen
- Raises blood levels more, and for longer
Vitamin D2 (ergocalciferol)
- Made by plants and fungi, such as UV-exposed mushrooms
- Traditionally the vegan option
- Raises blood levels less, particularly with big, infrequent doses
- Less common in Australian supplements
What the evidence says
- A 2012 meta-analysis of trials that compared the two head-to-head found vitamin D3 raised blood vitamin D (25-hydroxyvitamin D) significantly more than D2.
- The difference was biggest with large single or occasional (“bolus”) doses. With daily dosing, the difference wasn’t statistically clear.
- Both are turned into the same active hormone in the body. D3 seems to be held better and broken down more slowly.
- Most guidelines and the TGA-listed products you’ll find in Australian pharmacies use D3, which is why it’s usually the default.
Who might need a supplement
- People who get little sun: housebound or in aged care, covering skin for cultural or religious reasons, or working indoors all day
- People with naturally darker skin, who need more sun to make the same amount
- People with conditions that affect absorption, such as coeliac disease, inflammatory bowel disease or after weight-loss surgery
- Some medicines, such as certain seizure medicines, lower vitamin D
- Breastfed babies of mothers with low vitamin D, and pregnancy when levels are low: your doctor or midwife will advise
How much is enough, and too much?
- For most adults, a little safe sun covers it. Supplements are usually daily, low-dose and taken with a meal containing some fat. Your GP or pharmacist can suggest a dose that suits you.
- Daily is generally better than huge occasional doses. Some trials of very large yearly doses in older people found more falls and fractures, not fewer.
- Don’t take more than 4,000 IU (100 micrograms) a day unless your doctor advises it: that’s the adult upper limit used in the US and Europe. Too much can raise blood calcium, causing nausea, thirst, confusion and kidney problems.
- More isn’t better: in people with normal levels, extra vitamin D hasn’t been shown to prevent cancer, heart disease or early death.
Reading the label
- Colecalciferol (or cholecalciferol) = D3. Ergocalciferol = D2.
- 40 IU = 1 microgram. So 1,000 IU = 25 micrograms.
- Look for an AUST L or AUST R number, which shows the product is on the Australian Register of Therapeutic Goods.
- Calcitriol is a different, prescription-only medicine (the active hormone), used for kidney and parathyroid conditions, not general supplementation.
When to see a doctor
- Bone pain, muscle weakness or frequent falls
- You’re in a higher-risk group and haven’t had your level checked
- You’re taking high-dose vitamin D, or have kidney stones, kidney disease or high calcium
- Your level stays low despite supplements, which can point to an absorption problem
Common questions
Is vitamin D3 better than D2?
For raising blood vitamin D levels, yes. Trials comparing them show D3 raises and maintains levels better, particularly with large occasional doses. With daily doses the difference is smaller.
Is there a vegan vitamin D3?
Yes. Most D3 is made from lanolin in sheep’s wool, but vegan D3 made from lichen is available. Vitamin D2, from fungi or yeast, is also vegan.
What is colecalciferol?
Colecalciferol (also spelt cholecalciferol) is vitamin D3, the same form your skin makes in sunlight. It’s the form in most Australian vitamin D supplements.
How much vitamin D should I take a day?
It depends on your sun exposure, risk factors and blood level. Many adults at higher risk take a low daily dose. Don’t go above the adult upper limit (3,200 IU or 80 micrograms a day in Australia; 4,000 IU or 100 micrograms in the US and Europe) unless a doctor advises it. Ask your GP or pharmacist.
Can you take too much vitamin D?
Yes. Very high doses over time can raise calcium in the blood, causing nausea, vomiting, thirst, confusion and kidney damage. Sunlight alone doesn’t cause vitamin D overdose.
Sources
- Tripkovic L et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D: systematic review and meta-analysis. Am J Clin Nutr 2012
- healthdirect: Vitamin D and your health
- NIH Office of Dietary Supplements: Vitamin D fact sheet for health professionals. adult upper limit 4,000 IU (100 micrograms) a day; 40 IU = 1 microgram; D2 vs D3