Water Soluble Vitamin A Is 10 Times As Toxic As Fat-soluble

[j.]

Water-miscible, emulsified, and solid forms of retinol supplements are more toxic than oil-based preparations.

From wikipedia:

Researchers have succeeded in creating water-soluble forms of vitamin A, which they believed could reduce the potential for toxicity.[58] However, a 2003 study found water-soluble vitamin A was approximately 10 times as toxic as fat-soluble vitamin.[59] A 2006 study found children given water-soluble vitamin A and D, which are typically fat-soluble, suffer from asthma twice as much as a control group supplemented with the fat-soluble vitamins.[60]

Link

 

[Gabriel]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Maybe this study can also be interpreted the other way round: While taking micellized water-soluble Vitamin A (i.e. Nutrisorb A), you only need 1/10th of the dose for the same effect?? Has anybody ever compared Nutrisorb A to other Vitamin A sources in their potency (i.e. acne-reducing effects)?

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Good possibility, Gabriel. Since it isn't stored in the liver, the concentration in the blood is higher. (is that correct? or are they stored?)

 

[Gabriel]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

I'm not sure about whether there is a difference in liver storage. Both micellized and oil forms consist of retinyl-palmitate (Retinol+Palmitic acid) and should hence be used by the body the same way. I think the difference lies in absorption, with micellized being absorbed more efficiently. Unfortunately the authors of the study above don't say a word why the micellized are "more toxic".

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

I read on another forum the claim that the water soluble form isn't stored by the liver, it seems false.

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

This website claims water soluble vitamin A isn't stored in the liver.

 

[Gabriel]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

After some painful long digging in old papers, I finally found a paper that compared water-soluble to lipid vitamin a, interestingly on acne patients (source). They observed that the absorption of water-soluble vitamin a is much higher than oil-based vitamin a and that at the same doses, water-soluble vitamin a was more effective than oil-based vitamin a.

I haven't found an answer to the question though whether water-soluble vitamin a is not stored in the liver.

The conclusion for me is: When one takes micellized, emulsified or solid supplements of vitamin A, they might need much less IE than when taking vitamin a disolved in oil to have the same effect.

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

What's the process of getting things stored in the liver? Isn't just that there is vitamin A in the bloodstream, and the liver takes some, regardless of how it got there? If so, water soluble vitamin A would be stored in the liver just like regular vitamin A, unless the it is chemically different; a slightly different substances but with similar actions.

 

[Gabriel]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Retinol-esters such as retinylpalmitate are hydrolysed into Retinol within the gut. The retinol is then taken up by enterocytes (our main absorbing gut cells). Within the enterocyte, tetinol is again esterized with palmitate into retinylpalmitate (don't ask me why). Then, the retinylpalmitate is packed into chylomicrons. These are special lipoproteins (=little droplets with both lipids and proteins ). The chylomicrons are excreted by the enterocytes into lymph vessels. From the lymph vessels they are transported into the venous blood circulation and eventually the chylomicron reaches the liver. The liver has a high affinity for chylomicrons because it carries specialized receptors so that 60-70% of the chylomicron-vitamin A is taken up by the liver.

Water soluble vitamin a may somehow divert that process, i.e. when the micelle-vitamin A is directly transported into the blood, without being disassembled and repacked by the enterocytes. This could happen either through transcellular or paracellular transport.

I cant give you any studies though whether that is true.

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Apparently the liver does indeed store it, at least in guinea pigs.

Vitamin A in a water-soluble form, whose mode of preparation is a trade secret, was injected in a dose of 12, 000 I. U. into the heart of 12 guineapigs of 400 to 500 g. weight, which were killed 5, 10, 15, 35, 45 or 60 min. later. In the blood serum the values fell steadily from 10, 000 I. U. per 100 ml. after 5 min. to 39 after 60 min. The values in the liver rose equally steadily from 50 I. U. per g. after 6 min. to 380 after 60 min. [the graphs for blood and liver are reversed]. It is calculated that after an hour 56 per cent, of the vitamin A administered had been incorporated in the liver.
In 12 guineapigs given 40, 000 I. U. of the water-soluble vitamin A by intramuscular injection, and killed 3, 6, 9, 12, 15 or 24 hr. later, the total content of the liver was 6000 I. U. after 3 hr., and reached a maximum of 26, 000 after 9 hr., representing 65 per cent. of the vitamin A injected

Link

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

So from study above, it took nine hours for the vitamin A to accumulate in the liver, which means that after taking water soluble vitamin A, for 9 hours the blood level stays much higher than usual, considering that people seem to take the same IU amounts in water soluble vitamin A as in fat soluble vitamin A, with the former being absorbed apparently more than 10 times than the latter.

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Claim: Water-soluble vitamin A results in higher blood levels, with less accumulation in the liver

 

[Gabriel]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Nice find! Yeah that might be one explanation. However, 50-60% of water-soluble vitamin a ending up in the liver sounds like pretty similar to 2/3 uptake of chylomicron-vitamin a into the liver (study). So I think while the first part of the claim is right (higher water-soluble than lipid vitamin a in serum), the second part, less is stored in the liver, is false.

Also, in that study they observed 56% uptake of water-soluble vitamin a already after one hour when the vitamin a was directly given into the blood circulation (heart injection), and 8 hours only after intramuscular injection. That is quite similar to 67-75% uptake after 30-60min of chylomicron-vitamin a in the study I linked above. So I think also in that aspect both forms appear quite similar.

I have another idea though: For optimal absorption of vitamin a, hydrolysis of retinylpalmitate into Retinol+Palmitic acid within the gut appears to be an imporant step. Maybe vitamin A in small droplets of micelles or emulsions is easier hydrolysed than in large oil drops? If more of it is hydrolysed then more may also be taken up by the enterocytes leading to higher serum levels.

 

[Gabriel]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Somewhat on topic: Early-life supplementation of vitamins A and D, in water-soluble form or in peanut oil, and allergic diseases during childhood

Conclusion: Supplementation of vitamins A and D in water-soluble form seems to increase the risk of allergic disease up to the age of 4 years compared with supplementation with the same vitamins given in peanut oil.

 

[BaconBits]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Does this only apply to micelized vitamin a or all dry vitamin A?

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

It seems that it's BS. Peat uses micellized Vitamin A on his skin (nutrisorb). I posted an exchange with Peat about this in the depository:

I asked Peat whether Micellized Vitamin A (nutrisorb) might be more risky and attached this study:

Water-miscible, emulsified, and solid forms of retinol supplements are more toxic than oil-based preparations.

I think it would have been possible for any one of those six co-authors to write an equally worthless paper. The amount of "water-miscible, emulsified, and solid preparations" would have been about 40,000 i.u. per day for an average sized person, but there was no clear definition of what they mean by chronic hypervitaminosis A.

 

[BaconBits]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

It seems that it's BS. Peat uses micellized Vitamin A on his skin (nutrisorb). I posted an exchange with Peat about this in the depository:

I asked Peat whether Micellized Vitamin A (nutrisorb) might be more risky and attached this study:

Water-miscible, emulsified, and solid forms of retinol supplements are more toxic than oil-based preparations.

I think it would have been possible for any one of those six co-authors to write an equally worthless paper. The amount of "water-miscible, emulsified, and solid preparations" would have been about 40,000 i.u. per day for an average sized person, but there was no clear definition of what they mean by chronic hypervitaminosis A.

What about the difference between synthetic and extracted from fish liver ("natural"). Is any of them better or worse. maybe I shoul open a new topic.

 

[j.]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

What about the difference between synthetic and extracted from fish liver ("natural"). Is any of them better or worse. maybe I shoul open a new topic.

I personally got allergic reactions to two "natural" products, Carlson and Country Life. I also got allergic reactions on the synthetic Carlson. I'm using a micellized vitamin A (not available internationally) at the moment and it's working fine.

 

[BaconBits]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

What about the difference between synthetic and extracted from fish liver ("natural"). Is any of them better or worse. maybe I shoul open a new topic.

I personally got allergic reactions to two "natural" products, Carlson and Country Life. I also got allergic reactions on the synthetic Carlson. I'm using a micellized vitamin A (not available internationally) at the moment and it's working fine.

Oh, so synthetic would be less allergenic, more hypoallergenic. But I heard the the "natural" fish liver version would be more potent, at least Weston A. Price people have been saying that?

 

[Danno]

Re: Water Soluble Vitamin A is 10 times as toxic as fat-solu

Why do you need to supplement vitamin A anyway? Isn't there enough in liver? Like 4 oz beef liver once a week, and maybe a little chicken liver plus all the vit a from dairy.