Cautions to Synthetic Vitamin D3

A found some information which may be of interest to anyone here who is taking vitamin D supplements.
First I noticed the passage here:

When the parathyroid hormone or a or a toxic form of vitamin D is given to young rats, calcium is withdrawn from the bones, simulating the withdrawal of calcium during stress, and advanced old age is produced, including wrinkles, squeaky voices, cataracts, and shriveled sex glands.27 If the soft tissues are harmed in any way, the calcium withdrawn from the bones is laid down in the damaged area.

Davis, Adelle. Let’s Get Well: Adelle Davis has sold over 10 Million Books (pp. 116-117). Adelle Davis Foundation. Kindle Edition.

wondering what this toxic vitamin D was I searched further in the same book and found this:

Vitamin D, however, is essential before the kidney tubules can reabsorb calcium efficiently. If this vitamin is undersupplied, as it frequently is in stone-formers, large amounts of both calcium and phosphorus are excreted in the urine.24 Excessive synthetic vitamin D, or irradiated ergosterol, such as 5,000 to 25,000 units daily, likewise causes a heavy loss of these minerals.24–26

Davis, Adelle. Let’s Get Well: Adelle Davis has sold over 10 Million Books (p. 215). Adelle Davis Foundation. Kindle Edition.

Since both mentioned the withdrawal of calcium I wondered if the toxic vitamin D was the synthetic form. This led me to find this page which you might be best to read in full.

As it is mid winter now in Australia, this has led me to throw out my vitamin D supplements and go back to good old codliver oil. If not conclusive, irradiated lanolin sounds pretty disgusting IMHO.

The Price Potteger foundation also claims that codliver oil on its own is not nearly as effective as when taken together with butter made in summer or autumn. This is old research and they did not know what was in the butter and called it something like factor x. It has since been discovered that this is vitamin K2. Because of this I also take vitamin K2 every morning and the codliver oil in the middle of the day.


I would assume supplement makers are not using the toxic form of vitamin D3. If so, I doubt they’d be able to survive.

As for supplemental D3, too little is bad and too much is bad. It’s a U-shaped curve, but that curve is different for everyone as our independent biologies affect our absorption. However, based on my reading, a dosage of between 800-4,000 IUs of supplemental D3 should be at the bottom of the U for 90% of individuals (maybe more). Below 800 you are risking having too little. Above 5000 you are risking having too much. I take 5,000 IU because I was deficient when I was tested last and this is a value to treat deficiency. For some reason, supplement companies mostly sell either 1,000 or 5,000 IUs.

In a perfect world, I’d want to take 2,000 - 4,000 IUs daily in the morning.


If you are making more hormones (say TRT, or exercise-induced testosterone, or female hormone replacement, etc) wouldn’t having slightly more vitamin d be a benefit (although not a massive excess).

I never checked my vitamin D until recently (and after I started supplementing), but I take 5000 IU daily and my last serum vitamin d measurement was 32. Maybe that will change as it accumulates, but I can’t say I’m too high now. Maybe I should cut down to 5000 IU every two days?

I wonder if you read the world Health website article? Most supplement makers are using the synthetic version. People like it because it quickly raises blood levels, but there are real problems they discuss. Personally I am not going to risk taking something that people knew more than 50 years ago accelerated ageing when I can just take codliver oil instead. My bet is that the toxicity ascribed to taking too much vitamin D is probably caused by the synthetic form.


Exactly what I have done, this makes a lot of sense reading about synthetic Vitamin D. Cod liver oil also gives you a nice amount of Omega’s and Vitamin A and E but not too much. Bioavailability is superior as well.

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I agree with this, but animals process vitamin D differently than humans and it is dangerous to give large doses to animals. I forget the source for this, but am pretty sure it is well known among animal nutrition people. It’s not as dangerous for people.

I use Sperti lamps after my daily shower. I have 2 now because I’m impatient and can afford it, but went with one for over 10 years. My vitamin D bounced about 25 points after I got the second one. They do work.

Cod liver oil is brilliant.

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I have a bottle of Nordic Cod Oil (for dogs). It doesn’t list vit D. It contains Omegas, vit A and E.

It strikes me you are calling D2 (ergocalciferol) the synthetic version. I agree that D3 (cholecalciferol) is better, but arguably it is also made synthetically at times.

I use NOW cod liver oil, it contains 400 IU of vitamin D. I am happy with their formula. But I have read that there are smaller companies making purer Cod liver oil, but they have a shorter shelf life and can not be bought at iHerb, they also need to be refrigerated. You might want to check out if these are available in your local area.


Fascinating. I have been taking 5000 MG vitamin D with K2. I was interested to see the effect on kidney stones. Having just had an episode, I learned I need to drink more milk among other things. I think I will try cod liver oil also and K2 also.

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The abstract of the study cited in the article is found below.

Fibromuscular intimal thickening was seen in the ascending and thoracic aorta of the swine fed 62,500 IU of vitamin D3/kg of diet for three months duration; and after 3 months of vitamin D3 withdrawal, atherosclerotic lesions were found. In rabbits, pronounced aortic smooth muscle cell necrosis developed with the forced feeding of 10,000 IU vitamin D3 dissolved in corn oil/kg body weight/day for 14 days. Serum analyses indicated that blood calcium did not differ from that of animals fed corn oil alone, but that the level of serum 25-hydroxy-vitamin D3 measured by HPLC was 30 times that in the control animals. These data suggest that choleclaciferol (the oxidized sterol with vitamin D3 activity) has a very destructive influence on the integrity of arterial wall, and that smooth muscle cell necrosis could be caused by enhanced membrane permeability to Ca2+ following 25-hydroxy-vitamin D3 incorporation into smooth muscle cell membranes.

That is 62,500 IU per kg for the swine, and 10,000 IU per kg for rabbits. Conversion of dosage from pig to human is to divide by .946, so almost one.

That is per kilogram. So multiply by your weight.


In other words, we have to take astronomical amounts of D3 to have similar results. Is it right?


The swine dose for a 60 kg (130 lbs) individual converts to more than 3 million IUs per day.

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Yet the article cited by the original poster states:

In a controlled study synthetic vitamin D given to swines showed pathological damage to thoracic aorta in swine consuming the equivalent of 11000 IU of vitamin D3 daily; and lower doses of 2200 IU of D3 daily worsened atherosclerosis in the animals on high fat diets.

Somewhat confusing.


The original poster cited an article, and in that article, a study was cited, which I posted above. So I corrected my post to read:

The abstract of the study cited in the article is found below.

There is another study cited in the article.

That involved two month old piglets.

The effects of five different dietary levels of vitamin D3 on the coronary arteries of groups of 17-60 2-month old weanling Yorkshire swine were studied.


Great job finding that. So I wonder which study the original article derived the 11,000 IU vitamin D3 equivalent from?

The above study abstract you linked to quotes dosage per ton of feed.

Do you know what type of stones they are? Taking glycine can cause calcium - oxalate stones to form if a person has trouble absorbing vitamin B6. Getting a vitamin B injection usually fixes the absorption problem so that you are able to absorb it by mouth after that. My father was a doctor who practiced until he was 75. He used vitamin B injections to fix just about everything. With most kidney stones you also need to make sure you are getting enough magnesium with the B6.

Not sure how that came across - the world health article was about D3. Maybe you misread me mentioning K2? I am not really up with the differences in D2 and D3 - I just know that synthetic vitamins can be toxic because my dad taught me that. He said the drug companies used them to discredit vitamins and say they are dangerous. I must say I was a bit shocked when I discovered that most vitamin D was synthetic. It makes sense though. 20 years ago everyone considered vitamin D toxic. Then suddenly it came into vogue.

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The lamps sound great - I have an IR one I am lying under right now as I just woke up. I will check out the Sperti ones as it is mid winter here and I am really missing my daily mid day dose of sun :slight_smile:

I believe it they are calcium stones. I have been taking glycine and a nitric oxide supplement that has a fair amount of vitamin C. Both bad.