Confused about Vitamin A/retinol

pamojja

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Is it something we should be avoiding, or taking?
And then, how much? - The uncomfortable answer to that is: we are all different with different bio-chemical individuality. So no real hard and fast answer.

One reason for taking preformed retinol over beta-carotene would be that it has been found in a study of females that up to 50% of them can't convert beat-carotene into active vitamin A. Additionally calculated from food intake questionares in the US, half its population doesn't reach the RDA for vitamin A (which includes the precursor beta-carotene with the wrong assumption it would always convert).

Lastly, traditional societies alledgedly got multiples of preformed vitamin a from their diet. Just think of the offal most of us nowadays never eat. Some of them:

Link

"1. Native Eskimos: 5.4x calcium, 1.5x iron, 7.9x magnesium, 1.8x copper, 49x iodine, 10x vitamin A, 10x vitamin D

2. Indians of Northern Canada: 5.8x calcium, 5.8x phosphorus, 2.7x iron, 4.3x magnesium, 1.5x copper, 8.8x iodine,10x vitamin A, 10x vitamin D

3. High Mountain Swiss: 3.7x Calcium, 2.2x phosphorus, 2.5x magnesium, 3.1x iron, 10x vitamin A, 10x vitamin D

4. Gaelics in the Outer Hebrides: 2.1x calcium, 2.3x phosphorus, 1.3x magnesium, 1x iron, 10x vitamin A, 10x vitamin D

5. Aborigines of Austrailia: 4.6x calcium, 6.2x phosphorus, 17x magnesium, 50.6x iron, 10x vitamin A, 10x vitamin D
How to find out? Best test your serum retinol and retinol binding protein levels (RBP). Start low dose and increase gradually over months, weeks and years. Then retest. Adjust dose accordingly.
 

Wishful

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I think Pamoji's advice is good: if you're truly concerned about your VitA level, do testing and experimentation to optimize. I think that if you're not facing noticeable health problems from VitA deficiency, just follow a healthy diet and not bother with supplements. The same for other nutrients: if you're actually missing something due to dietary restrictions, use supplements, but otherwise they're probably not worth the money or potential risks.

I think that most of the marketing claims of "supplement x will boost your health!" are based on some questionable studies that show a barely measurable difference, if you view the data just the right way.
 

Wolfcub

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The way I feel about vitamin A (and I don't know enough about it to be honest) is that if we're eating vitamin A rich foods in a balanced diet and there's no malabsorption issue, then supplementing it could possibly be inadvisable. Perhaps with the exception of a multi-vitamin/mineral tablet once a day if not enough food containing it has been eaten.
Because it's a stored vitamin (in the liver I believe??), too much can be toxic I think. But that's all I know.
 

pamojja

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How to find out? Best test your serum retinol and retinol binding protein levels (RBP). Start low dose and increase gradually over months, weeks and years. Then retest. Adjust dose accordingly.
Personally I went very slowly repleting my serum retinol levels. Took me about 7 years untill I crossed above 20.000 IU of supplemented preformed vitamin A per day. With that my infrequent psoriasis outbreaks ceased forever since.

Now after 12 years in average with 16.000 IU/d I've reached upper normal of serum levels, and therefore decreased the daily vitamin A dose again. Never experienced any negatives.

But as said, might be different to everyone.
 

splusholia

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I wanted to take some liver capsules to improve my iron. I got scared though, because some people seem to believe (and have posted on this forum) that retinol in any amount is toxic to the body. I guess I was wondering whether there is actually any genuine scientific evidence that vitamin A is harmful (except, obviously, if overdosing). I find it hard to believe that this can be the case, especially considering that chart regarding vitamin A intake in traditional societies.

Good idea to test serum retinol though. I’ll look into that.
 

pamojja

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There is a comprehensive article of vitamin A hypervitaminosis at wikipedia:

https://en.wikipedia.org/wiki/Hypervitaminosis_A

Types of toxicity
  • Acute toxicity occurs over a period of hours or a few days, and is less of a problem than chronic toxicity.
  • Chronic toxicity results from daily intakes greater than 25,000 IU for 6 years or longer and more than 100,000 IU for 6 months or longer.
There are however scary reports of toxicity on the internet with 100.000 IU/d taken for only a few days. So always act reasonably. Also always consider one might be much more sensitive than anyone else. Therefore better start very low dose and increase slowly.
 
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I felt better from taking it but it's one to be careful with and not keep taking if you have any adverse reaction. Small amounts are safest.