Vitamin D3 and vitamin D2 are two genuine forms of vitamin D. D3 is called cholecalciferol; D2 is ergocalciferol. They share nutritional roles, but differ in their sources and in how effectively they raise the blood marker commonly used to assess vitamin D status.
For a practical choice, compare form, amount, dietary suitability and the product you can use consistently. A preference for D3 is not a reason to increase the dose, and a prescribed D2 preparation should not be replaced without advice.
D3 and D2 side by side
Question
Vitamin D3
Vitamin D2
Chemical name
Cholecalciferol.
Ergocalciferol.
Source examples
Made in skin in response to sunlight. Supplement sources can include lanolin or non-animal sources such as lichen.
Associated with fungi, including mushrooms exposed to ultraviolet light.
Is it vitamin D?
Yes.
Yes. D2 is not a fake or inactive substitute.
Normal nutritional roles
Helps regulate calcium and phosphate for bones, teeth and muscles.
Shares those vitamin D roles.
Unit conversion
1 microgram equals 40 IU.
1 microgram equals 40 IU.
Vegan suitability
Requires a verified suitable source and whole formulation.
Often compatible with non-animal sourcing, but check the whole formulation.
Format
Can appear in different oral formats and fortified foods.
Can also appear in different oral formats and fortified foods.
What the names tell you about origin
D2 is produced from a fungal precursor called ergosterol following ultraviolet exposure. UV-treated mushrooms are one food example, although ordinary mushrooms should not automatically be assumed to supply the same amount.
D3 is the form skin makes in response to sunlight. For supplements, animal-derived lanolin and non-animal sources such as lichen are possible. “D3” names the molecule, not a complete sourcing declaration.
That matters if you are vegan or avoid particular animal materials. Look for an explicit statement covering the ingredient and finished product, including the capsule shell or other ingredients. Do not assign a source to an individual product just because another brand uses it.
Fortified cereals, spreads and drinks may use either form. The useful first check is what the product actually adds and how much your usual serving supplies.
Which raises vitamin D blood levels more effectively?
A 2023 meta-analysis covering 20 comparative studies found D3 more effective on average at raising total 25-hydroxyvitamin D, usually written as 25(OH)D. This blood marker helps assess status, but an average difference in a marker is not proof that every D3 product produces superior clinical health outcomes for every person. Amounts, schedules, participants and study methods affect the comparison.
The evidence also needs context rather than a selective headline. An older 2012 systematic review did not find the same overall difference in its daily-dosing subgroup. That does not erase the later pooled finding; it shows why the dosing pattern and studies included matter.
A balanced reading is that D3 often has an advantage for raising the measured marker, while D2 remains a valid vitamin D form. They do not justify changing a prescribed preparation yourself.
The units are identical, not a potency shortcut
For both forms, 1 microgram of vitamin D equals 40 international units, or IU. Ten micrograms therefore equals 400 IU whether the label says D2 or D3.
The shared unit conversion does not mean every biological response is identical. Equally, evidence of a different average blood response does not allow you to invent a dose-exchange formula.
Compare like units and the full stated serving. A quantity per drop is different from a quantity per dropper, and a quantity per capsule may differ from the daily serving. Do not switch a prescribed product by matching a bottle headline alone.
Form and delivery format are separate choices
D2 versus D3 concerns the vitamin form. Liquid versus tablet or capsule concerns how it is supplied. One does not determine the other.
A liquid may suit someone who dislikes swallowing tablets, but it needs careful measurement. A capsule offers a fixed unit, though the serving may involve more than one. Neither format is universally better merely because it is liquid or solid.
For a vegan shopper, source verification may settle the decision first. For someone using a prescribed preparation, continuity with the treatment plan matters more than a general shopping preference. For routine use, practical directions and the intended amount remain central.
A hypothetical serving-and-value comparison
Imagine a bottle containing 75 tablets, each supplying 10 micrograms, with one tablet as its stated daily serving. It provides 75 daily servings.
Now imagine a liquid containing 150 measured servings, each also supplying 10 micrograms. It provides twice as many equivalent-amount servings. If the liquid cost twice as much as the tablets, their cost per daily serving would be equal; otherwise, divide each actual purchase price by its serving count.
These are hypothetical examples, not iLoveVits specifications or instructions to choose a liquid. Compare the complete formulation, source and measuring directions as well as cost. A larger bottle or higher IU number alone does not establish better value.
Keep routine strength separate from form preference
The NHS advises adults to consider 10 micrograms daily during autumn and winter, with year-round advice for some groups. See why vitamin D matters for the full UK seasonal explanation.
A 100-microgram serving equals 4,000 IU and reaches the NHS adult daily upper amount unless medically advised. It is not the routine 10-microgram option. Choosing D3 over D2 does not justify choosing ten times as much.
Vitamin K is a separate ingredient. Adding K2 does not make excessive vitamin D acceptable. Read vitamin D and K2 explained for that combination decision.
Suitability and prescribed preparations
Follow your clinician’s instructions for diagnosed deficiency and ask a pharmacist before replacing prescribed D2 with D3 or changing the schedule. Check for vitamin D already present in multivitamins and other blends. Seek tailored advice for conditions affecting calcium regulation, kidney problems or questions involving medicines; vitamin K supplements need particular care with warfarin and related medicines. Do not stop or adjust prescribed treatment yourself.
Considering a high-strength D3 combination?
If that strength and combination have been established as appropriate for you, explore iLoveVits Vitamin D3 & K2 with Vitamin C. It contains 4,000 IU, equivalent to 100 micrograms, of D3, plus 200 micrograms of K2 MK-7 and vitamin C.
This is a high-strength formulation at the adult daily upper amount, not a default routine choice or an addition to separate vitamin D. Its K2 does not remove that distinction.
Frequently asked questions
Is D2 real vitamin D?
Yes. Ergocalciferol is a genuine vitamin D form, even though D3 often raises the measured blood marker more effectively on average.
Is all D3 vegan?
No. D3 can have animal or non-animal sources. Verify the actual product rather than assuming either.
Can I exchange equal micrograms of prescribed D2 and D3?
Do not change a prescribed regimen without a pharmacist or clinician. Equal units do not establish that a treatment substitution is appropriate.
Does liquid vitamin D work better than capsules?
Not universally. Compare the form, amount and preparation, then choose a suitable delivery format.
Does a better blood-marker response mean better results for everything?
No. A 25(OH)D outcome does not automatically establish superior effects on every clinical outcome.
Should I take more D2 to compensate?
Do not invent a compensating amount. Follow routine guidance or your individual treatment plan.
About this guide: Published by iLoveVits, a food-supplement retailer. This is general educational information. References are linked for checking the underlying evidence; ingredient research does not establish results for an iLoveVits finished product. Individual medical advice takes priority.
Vitamin D3 vs Vitamin D2
Vitamin D3 and vitamin D2 are two genuine forms of vitamin D. D3 is called cholecalciferol; D2 is ergocalciferol. They share nutritional roles, but differ in their sources and in how effectively they raise the blood marker commonly used to assess vitamin D status.
For a practical choice, compare form, amount, dietary suitability and the product you can use consistently. A preference for D3 is not a reason to increase the dose, and a prescribed D2 preparation should not be replaced without advice.
D3 and D2 side by side
What the names tell you about origin
D2 is produced from a fungal precursor called ergosterol following ultraviolet exposure. UV-treated mushrooms are one food example, although ordinary mushrooms should not automatically be assumed to supply the same amount.
D3 is the form skin makes in response to sunlight. For supplements, animal-derived lanolin and non-animal sources such as lichen are possible. “D3” names the molecule, not a complete sourcing declaration.
That matters if you are vegan or avoid particular animal materials. Look for an explicit statement covering the ingredient and finished product, including the capsule shell or other ingredients. Do not assign a source to an individual product just because another brand uses it.
Fortified cereals, spreads and drinks may use either form. The useful first check is what the product actually adds and how much your usual serving supplies.
Which raises vitamin D blood levels more effectively?
A 2023 meta-analysis covering 20 comparative studies found D3 more effective on average at raising total 25-hydroxyvitamin D, usually written as 25(OH)D. This blood marker helps assess status, but an average difference in a marker is not proof that every D3 product produces superior clinical health outcomes for every person. Amounts, schedules, participants and study methods affect the comparison.
The evidence also needs context rather than a selective headline. An older 2012 systematic review did not find the same overall difference in its daily-dosing subgroup. That does not erase the later pooled finding; it shows why the dosing pattern and studies included matter.
A balanced reading is that D3 often has an advantage for raising the measured marker, while D2 remains a valid vitamin D form. They do not justify changing a prescribed preparation yourself.
The units are identical, not a potency shortcut
For both forms, 1 microgram of vitamin D equals 40 international units, or IU. Ten micrograms therefore equals 400 IU whether the label says D2 or D3.
The shared unit conversion does not mean every biological response is identical. Equally, evidence of a different average blood response does not allow you to invent a dose-exchange formula.
Compare like units and the full stated serving. A quantity per drop is different from a quantity per dropper, and a quantity per capsule may differ from the daily serving. Do not switch a prescribed product by matching a bottle headline alone.
Form and delivery format are separate choices
D2 versus D3 concerns the vitamin form. Liquid versus tablet or capsule concerns how it is supplied. One does not determine the other.
A liquid may suit someone who dislikes swallowing tablets, but it needs careful measurement. A capsule offers a fixed unit, though the serving may involve more than one. Neither format is universally better merely because it is liquid or solid.
For a vegan shopper, source verification may settle the decision first. For someone using a prescribed preparation, continuity with the treatment plan matters more than a general shopping preference. For routine use, practical directions and the intended amount remain central.
A hypothetical serving-and-value comparison
Imagine a bottle containing 75 tablets, each supplying 10 micrograms, with one tablet as its stated daily serving. It provides 75 daily servings.
Now imagine a liquid containing 150 measured servings, each also supplying 10 micrograms. It provides twice as many equivalent-amount servings. If the liquid cost twice as much as the tablets, their cost per daily serving would be equal; otherwise, divide each actual purchase price by its serving count.
These are hypothetical examples, not iLoveVits specifications or instructions to choose a liquid. Compare the complete formulation, source and measuring directions as well as cost. A larger bottle or higher IU number alone does not establish better value.
Keep routine strength separate from form preference
The NHS advises adults to consider 10 micrograms daily during autumn and winter, with year-round advice for some groups. See why vitamin D matters for the full UK seasonal explanation.
A 100-microgram serving equals 4,000 IU and reaches the NHS adult daily upper amount unless medically advised. It is not the routine 10-microgram option. Choosing D3 over D2 does not justify choosing ten times as much.
Vitamin K is a separate ingredient. Adding K2 does not make excessive vitamin D acceptable. Read vitamin D and K2 explained for that combination decision.
Suitability and prescribed preparations
Follow your clinician’s instructions for diagnosed deficiency and ask a pharmacist before replacing prescribed D2 with D3 or changing the schedule. Check for vitamin D already present in multivitamins and other blends. Seek tailored advice for conditions affecting calcium regulation, kidney problems or questions involving medicines; vitamin K supplements need particular care with warfarin and related medicines. Do not stop or adjust prescribed treatment yourself.
Considering a high-strength D3 combination?
If that strength and combination have been established as appropriate for you, explore iLoveVits Vitamin D3 & K2 with Vitamin C. It contains 4,000 IU, equivalent to 100 micrograms, of D3, plus 200 micrograms of K2 MK-7 and vitamin C.
This is a high-strength formulation at the adult daily upper amount, not a default routine choice or an addition to separate vitamin D. Its K2 does not remove that distinction.
Frequently asked questions
Is D2 real vitamin D?
Yes. Ergocalciferol is a genuine vitamin D form, even though D3 often raises the measured blood marker more effectively on average.
Is all D3 vegan?
No. D3 can have animal or non-animal sources. Verify the actual product rather than assuming either.
Can I exchange equal micrograms of prescribed D2 and D3?
Do not change a prescribed regimen without a pharmacist or clinician. Equal units do not establish that a treatment substitution is appropriate.
Does liquid vitamin D work better than capsules?
Not universally. Compare the form, amount and preparation, then choose a suitable delivery format.
Does a better blood-marker response mean better results for everything?
No. A 25(OH)D outcome does not automatically establish superior effects on every clinical outcome.
Should I take more D2 to compensate?
Do not invent a compensating amount. Follow routine guidance or your individual treatment plan.
Sources and further reading
About this guide: Published by iLoveVits, a food-supplement retailer. This is general educational information. References are linked for checking the underlying evidence; ingredient research does not establish results for an iLoveVits finished product. Individual medical advice takes priority.