Sources of Vitamin D - Cholecalciferol and Ergocalciferol

by Leigh

I think "natural" vitamin D is a bit of a misnomer when talking about oral supplement forms. It does exist in a minority of products -- those that distill it from fish oil.

However, I find that most supplements contain vitamin D which is synthesized from lanolin (oil in sheep's wool). What you get may look like the vitamin D molecule, but it's not naturally occurring. It's manufactured.

Being a science geek (:-) you'll know that the manufactured molecules of vitamin D won't be exactly identical (on the subatomic level) to naturally occurring vitamin D.


Hi Leigh,

I think you are confused about the different sources of vitamin D. I'd recommend rereading what I wrote on my natural vitamin D page.

If anything is a misnomer, it would be calling vitamin D a "vitamin."

It's not a vitamin, actually, since the term vitamin is used when an organism cannot synthesize it in sufficient quantities - so it must be obtained through diet. Our skin is capable of producing all the vitamin D we need under the proper conditions.

Our ancestors did not have to worry about getting enough vitamin D. We do now because of our change in lifestyle.

  • Most of us spend the vast majority of our time indoors.

  • Most of us have moved too far away from the equator – so we can only make vitamin D during the warmer months.

  • Most of us have been conditioned to slather on the sunscreen when we do go outside.

  • Most of us shower after spending any time outside because we've gotten sweaty – that washes away any vitamin D the body may have been able to make.

We are blocking our natural ability to make vitamin D through proper sun exposure. This has created a great epidemic of vitamin D deficient people.

That leaves us with oral supplementation. There are two forms of non-prescription vitamin D supplements available to us – cholecalciferol and ergocalciferol.

Cholecalciferol is natural vitamin D, also called vitamin D3. Cholecalciferol is actually a prehormone. It is made by purifying the fat of lambs' wool.

I assure you it is in fact the EXACT same molecule that you would make in your skin. Perhaps you would prefer me to call it the bioidentical human form of vitamin D? I don't think most people would understand that term – besides, it's bulky.

I can go into detail about what happens to cholecalciferol after it is absorbed into the skin or taken orally if you (or anyone else) would like (just leave a comment below). But I don't think most people are all that interested in those details.

Ergocalciferol, on the other hand, is not a natural form of vitamin D. Also called calciferol or vitamin D2, it is made from radiating fungus. Vegans like to take this form because it is not derived from animals.

However, ergocalciferol is foreign to the human body. It is about half as potent as cholecalciferol yet has much greater chance of toxicity, especially at the higher dosages required to improve vitamin D levels.

So there you have it. Cholecalciferol, also called vitamin D3, is a completely natural form of vitamin D. It is the EXACT same molecule no matter if you make it from the sun or take it orally.

Let me know if you have any other questions about this (comment below).

Wishing you the best of health,

How to Boost Your Immune System

Comments for Sources of Vitamin D - Cholecalciferol and Ergocalciferol

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Vitamin D3
by: Anonymous

There is a new D3 form on the market from Whole Earth and Sea. It is made from lichen. So far so good. I cannot tolerate the lanolin based D3

Vitamin D3 and Allergies
by: Walter Sobchak

Thank you for this excellent article.

Another commenter noted being allergic to lanolin. Does this mean that those with such allergies cannot take the supplemental form of D3?

Based on my layperson's understanding of what I read in the article, the supplemental form of D3 is the same molecule made by our bodies. At a molecular level, are there allergenic properties that remain?

Thank you for the consideration.


Vitamin d supplementation for those allergic to lanolin
by: hilsy

Hi I wonder if you could advise on supplementing vitamin d for those with an allergy to lanolin? I know cod liver oil is a good source but in order to get enough vitamin d would involve taking too much vitamin a?

Kind regards


Hi Hilsy,

If you cannot supplement with oral D3, you are left with getting vitamin D the way nature intended - through sunlight. You're certainly right about the cod liver oil.

The sun is the best way to get your vitamin D anyway, although most of us cannot get enough proper sunlight because of our geographical location, jobs, etc. See my page on vitamin D and sun for more info.

There are also special tanning lights that allow your skin to make vitamin D. Amazon sells a table top lamp model, the D/UV-F KBD Sperti Fluorescent Table Top Lamp. I have no personal experience with any of these kinds of lamps though.

Wishing you the best of health,

How to Boost Your Immune System

About vitamin D
by: Anonymous

I am severely allergic to fish and lamb. And I am pretty low in vitamin D. Can you tell me which vitamin D would be safe for me. It would be much appreciated. Blessings.


Hi Anonymous,

I would not recommend the vitamin D2 to you, even though you are allergic to lamb and probably could not take the natural vitamin D3. We do not have a good understanding of the actions of the synthetic D2 - but we do know that is has higher toxicity compared to D3.

Have you looked into specially designed tanning systems? Dr. Mercola has them - I believe they are called Vitality stand-up systems.

Wishing you the best of health,

How to Boost Your Immune System

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