Vitamin A

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edited May 2018

Hi,
I read about vitamin A and I understand that the official RDI of this vitamin is expressed in μg RAE (Retinol Activity Equivalents), and this is 900 μg RAE for adults, with UL being 3000 μg RAE. Before this, it was expressed in IU (International Unit) with RDI of 3000 UI and no UL.
In a ordinary day, my vitamin A intake looks like this in Cronometer:

The problem is that I don't know which system should I use, that one in RAE or IU ?
The RAE shows that I don't have enough vitmain A (36%), but the IU shows that is more than enough (304%). Normally, these two % values should have been equal, because they represent the same thing. But they are not. That's what confuses me.

The conversions are:

1 IU = 0.3 µg retinol
1 IU = 0.6 µg beta-carotene
1 IU = 1.2 µg alfa-carotene or beta-cryptoxanthin

1 RAE = 1 µg retinol
1 RAE = 12 µg beta-carotene
1 RAE = 24 µg alfa-carotene or beta-cryptoxanthin

I apologise for my misspellings, as English is not my native language.

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Hi @Marus

Great eye!

It shouldn't matter which value you are using, RAE or IUs, to determine vitamin A intake, provided everything is being converted properly.

I did some quick math and all the sources of vitamin A add up correctly to RAEs (i.e. 328.1 mcg). What I can't figure out is how vitamin A IUs were determined from these RAEs as the math isn't adding up.

Are you adding in a supplement that is perhaps not being captured as a carotenoid or retinol?

I'll ask one of the staff member - @Marie_Eve_H , @Karen_Cronometer to chime in to see if I'm missing something.

Hang tight!

Kind regards,

Susan Macfarlane, MScA, RD
Registered Dietitian Nutritionist
cronometer.com
As always, any and all postings here are covered by our T&Cs:
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Hi, Susan !
No, I don't use supplements.
I think that IUs are not determined from RAEs, but from the raw µg of every substance.
The rules for IU are like this (at least in Cronometer):

• 1 IU = 0.3 µg retinol
• 1 IU = 0.6 µg beta-carotene
• 1 IU = 1.2 µg alfa-carotene or beta-cryptoxanthin

I apologise for my misspellings, as English is not my native language.

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@Marus

The conversion between RAEs and IUs is 3.33 so I'm confused as to why I'm not getting the correct total IU number. It seems that varied conversion factors may be in play.

Technically, IUs for vitamin A are being phased out, so to answer your question, I would probably look at RAEs instead, which for male adults is 900 mcg RAE or 700 mcg RAE for females.

Kind regards,

Susan Macfarlane, MScA, RD
Registered Dietitian Nutritionist
cronometer.com
As always, any and all postings here are covered by our T&Cs:
https://forums.cronometer.com/discussion/27/governing-terms-and-disclaimer

• edited May 2018
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Verry good point ! The conversion factor (the ratio IU/RAE) is 3.33 for the RDI and for the raw retinol too. The only thing that not follows the conversion factor si the carotenoids. They all have a conversion factor of 20 ! Meaning that in RAE, they count 6 time less that in IU. RAE being a new system, maybe the scientists have discovered that the carotenoids don't count that much as they thought. In conclusion, the scientists are saying, that now it is safe to eat a little more carotenoids.
Because retinol si the one that can cause toxicity, and it has the same "weigth" as the RDI has, in both systems (IU and RAE), I think either system it's ok. But I will chose RAE because it's more up to date.

I hope you understand what I meant, because English is not my first language and I'm not verry good at it.

I apologise for my misspellings, as English is not my native language.

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Hi Marus,

I would recommend that you look at the vitamin A breakdown for each food in your diary individually - do they all have values for RAE? Many brand name products in our database won't have a value listed for RAE, though they may have a value for IU. This could be throwing off your calculation.

Best,

Karen Stark
cronometer.com
As always, any and all postings here are covered by our T&Cs:
https://forums.cronometer.com/discussion/27/governing-terms-and-disclaimer

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Hi Karen,
I will check them tomorrow. Now it's 2 o'clock AM here, and the list has many foods.
But I don't think this is the problem, because if I calculate the RAE and IU from the source values of retinol and carotenoids, the result is exactly as it should for both.

I apologise for my misspellings, as English is not my native language.

• edited May 2018
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Rather than checking all the foods, I did something else. I took carrots and chicken liver only. They both have value listed for RAE. And the result is similar, 323% for IU and 91% for RAE. Still a big difference in percentage, even if all RAEs are present.

Anyway, there is no need for RAE values in the database, because this can be calculated from retinol and carotenoids values. But it seems that those are missing from some foods too.

I apologise for my misspellings, as English is not my native language.

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@Marus

Thanks for breaking this down. Very insightful!

Susan Macfarlane, MScA, RD
Registered Dietitian Nutritionist
cronometer.com
As always, any and all postings here are covered by our T&Cs:
https://forums.cronometer.com/discussion/27/governing-terms-and-disclaimer

• edited January 2020
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Your diet chart is really helpful it has mentioned [vitamin benefits] and the amount of vitamins present in a particular food. Thank you.

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Hey, actually you're right about the carotenoids - old vitamin A IU system is kind of deprecated -- it didn't take into account the differences between different micronutrients correctly.