How vitamin D is made from sheep wool - Feb 2011

What do sheep have to do with vitamin D supplements? Quite a bit, actually mates!

By Pamela Fayerman 8 Feb 2011

(Added to this page Oct 2011 a computation on amount of vitamin D produced per sheep - a LOT)
As health consumers, there may be times when too much information is not necessarily a good thing. I had one of those TMI moments the other day while chewing a chocolate-flavoured vitamin D supplement. My mouth started to feel, well, a little furry! It was a purely psychosomatic response to something I had just read in material sent to me from Jamieson Laboratories, Canada's biggest vitamin company.

While sampling one of the chewable vitamin D supplements, I did a rush-read on the accompanying literature. There was mention of sheep, lanolin and something called Quali-D. What? A vitamin supplement made from sheep's wool? How could this be?

Well, if you are, as I was, curious to know how Jamieson derives vitamin D from the wool of sheep, read on for the step-by-step explanation I later got from Michael McBurney, Head of Scientific Affairs for DSM Nutritional Products, the company which supplies the ingredient to Jamieson:

"Only vitamin D3 comes from wool from sheep. Some brands use vitamin D2 which comes from non-animal sources and is different from the vitamin D humans can synthesize from sun exposure," he said..

"DSM Nutritional Products’ natural-source Vitamin D3 is sold in crystalline, oil and powder forms. It is derived from lanolin taken from the wool of healthy live sheep living in Australian and New Zealand. An October 2003 Note for Guidance, adopted by the Committee for Proprietary Medicinal Products and the Committee for Veterinary Medicinal Products, states that derivatives of wool and hair from ruminants, such as lanolin, are compliant for use as natural-source supplements provided the wool or hair is taken from healthy, live animals.

Here are eight simplified steps from the field to Jamieson’s Vitamin D supplements:


2.  Wool is sheared from mature, live sheep.




6.  The crude cholesterol undergoes a series of further solvent extractions, washes and drying until it is extremely pure and crystalline. This purified cholesterol has been assessed as being fully compliant with the quality required for pharmaceutical manufacture by the European Directorate for Quality of Medicines.



Amount of D3 in wool 600,000 pills of 5,000 IU each

November 16, 2009
Vitamin D3 is often extracted from lanolin. I would like to know how much wool is necessary to produce say 1000 IU of vitamin D.
posted by davar to science & nature (8 comments total) 1 user marked this as a favorite
Like sheep's wool?
posted by ageispolis at 1:07 AM on November 16, 2009

Here's one back-of-the-envelope approach. I could have some or all of these numbers and calculations wrong, though, so be warned.

1000 IU of vitamin D3 is equal to 25 µg.

That has to be a very small fraction of one sheep's coat of wool, so small that perhaps a more interesting number is how many pills of vitamin D3 might one sheep's coat of wool make?

Vitamin D3 has a molecular weight of 384.64 g/mol, or 384.64 µg/µmol, so one pill has 25/384.64 = 0.065 µmol of D3.
"Crude lanolin constitutes approximately 5-25% of the weight of freshly shorn wool.
The wool from one Merino sheep will produce about 250-300 mL of recoverable wool grease."
Very roughly 50% of crude lanolin is made up of lanolin alcohols, which is a precursor to 7-hydroxycholesterol, which is what ends up getting converted into vitamin D3 (through UV irradiation).
Let's say that about 150 mL of lanolin precursor comes from one sheep, and that the specific density of lanolin is 0.99.
If 1g = 1 mL of water then we have about 148 g of lanolin.
Let's say we have a chemical reaction that synthesizes 7-hydroxycholesterol from lanolin precursor with an efficiency of 50% (I am totally guessing this efficiency — I have no idea what the real efficiencies of the intermediate chemical reactions are).

Then 148 g of lanolin precursor would give us 74 g of 7-hydroxycholesterol. The molecular weight of 7-hydroxycholesterol is 402.653 g/mol. Therefore, we have 76/402.653 = 0.18 mol of 7-hydroxycholesterol from one sheep's coat of wool.

Let's say that we expose 7-hydroxycholesterol to UV light and extract vitamin D3 with 99% efficiency. (Again, I'm guessing this conversion rate.)
So we end up with 0.18 mol of 7-hydroxycholesterol making 0.18 mol of vitamin D3.
We have 0.18 mol/sheep of vitamin D3, derived from one shorn sheep.
We also have 0.065 µmol/pill of vitamin D3, derived from a single 1000 IU D3 pill.
We invert this to get 15.3 million 1000 IU pills per mol of vitamin D3.
Therefore, we have 0.18 mol/sheep * 15.3M pills/mol ~ 2.8 million pills per sheep's coat.

I think the calculations are okay, but the specific numbers involved could be complete and utter nonsense. Some breeds of sheep may have coats of wool that give different quantities of crude lanolin, and in that crude lanolin, different fractions of lanolin alcohols that are used to make the cholesterol precursor.
The conversion efficiencies I used are completely made up. Hopefully this gives you an idea of how you might reach an answer, though.
posted by Blazecock Pileon at 2:24 AM on November 16, 2009 4 favorites

No doubt the efficiency has been improved in the past 45 years, but this 1964 patent on a process for extracting vitamin D from irradiated 7-hydroxycholesterol gives an example with 74% efficiency. Well, it calls it 7-dehydrocholesterol but I chalk that up to differences in nomenclature.
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This would be 3,000,000,000 IU per shearing (seems like way too much, but lets check)

at 40 micrograms per IU this is 0.75 billion micrograms = 750 grams = 1.6 lbs = possible
Assume that you get 10 years shearing per sheep.
Then 30 billion IU per sheep lifetime.
Taking 5,000 per day = 1.8 million IU per year = 1/16,000 of the vitamin D a sheep would produce in a lifetime.
If we assume, say, 100 lbs of meat per sheep, and that the sheep either produces meat or vitamin D3 (ignoring wool)
Then a 10 year's supply of vitamin D is the same as eating 1/1600 of a sheep
which is 100 lbs/1600 = 1/16 of a pound = 1 ounce.

So, having a 10 year supply of vitamin D3 is the same as eating 1 ounce of mutton per 10years = not very much

See also VitaminDWiki
