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Subject:
From:
"Hulshof, Paul" <[log in to unmask]>
Reply To:
Hulshof, Paul
Date:
Wed, 12 Nov 2014 07:44:28 +0000
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I think I pressed the send button too fast yesterday. 
In the IOM recommendations indeed only all-trans beta carotene is considered having 1/12 the activity of retinol in a mixed diet (however the report is not very straightforward in its nomenclature). We contributed in our Division with some controlled human intervention trials where the recommendation of IOM was based on. We made the calculations based on trans-beta-carotene, but I am not sure whether it was fully clear from the other studies whether trans or total beta-carotene was used. In the 2006 IOM report (dietary reference intakes: the essential guide to nutrient requirement) there is no differentiation between all-trans and cis isomers in calulating RAE, but the authors state that for background consultancy we have to go back to the original report. 
We have currently insufficient human feeding trials using stable isotopes or so to address this controversial  issue in a satisfactory way. In vitro work and animal studes are helpful in understanding mechanisms but should not be used to solve this for mixed human diets and populations that differ in vitamin A status.  As mentioned 9-cis beta-carotene is partly an artefact during sample analysis especially in green leafy vegetables (unless you want analists do their sample clean-up under green light €;-). And the 15,15'-mono-oxygenase enzyme to cleave trans trans-beta carotene is not specific for 9-cis-betacarotene as was shown by the work of Steven J Schwarz recently. And we do have more cis-isomers of beta-carotene showing up in food samples, which are sometimes not well separated from each other.   

For now I would suggest to treat cis-isomers not in the same way as trans isomers of beta-carotene but to treat them as if "other provitamin A carotenoids". So a factor 24.  These factors are BTW very rough estimates anyway with large confidence intervals. So a conservative approach; and lets wait for further good studies and a systematic evaluation from an authorative body.

best regards, Paul



===========================

Paul JM Hulshof

Division of Human Nutrition

Wageningen University

E: [log in to unmask]

T: +31 (0)317 484824

Web: http://humannutrition.wur.nl/UK/

===========================







Van: Charrondiere, Ruth (ESN) [[log in to unmask]]

Verzonden: dinsdag 11 november 2014 12:09

Aan: Hulshof, Paul; [log in to unmask]

Onderwerp: RE: Inquiry about vitamin A activity in cis-beta carotene







Dear Paul,
Thanks for your contribution. So you mean, for RAE cis-β-carotene should have the factor 12 or 24 applied?

Best wishes
Ruth
 


From: Hulshof, Paul [mailto:[log in to unmask]]


Sent: 11 November 2014 12:05

To: Charrondiere, Ruth (ESN); [log in to unmask]

Subject: RE: Inquiry about vitamin A activity in cis-beta carotene


 
Dear all,
 
There is quite some scientific debate about pro-vitamin A activity of cis-isomers of carotene (actually we do not it so very well). And related
 to this it should be noted that the presence of 9-cis-betacarotene in food samples (especially in green leafy vegetables) is partly an artefact because of sample analysis. Therefore I agree that it is currently best to follow the IOM recommendations for the
 calculation of RAE. 
 
Best regards,
 
Paul
 
 
++++++++++++++++++++++++++++++++++++++++++++
Ir Paul JM Hulshof
Division of Human Nutrition
Wageningen University
Tel: +31 (0)317 484824
Fax: +31 (0) 317 483342
E-mail:
[log in to unmask]
Website:
http://www.humannutrition.nl
++++++++++++++++++++++++++++++++++++++++++++
 
 
 
 


From: Food Composition Discussion Group [mailto:[log in to unmask]]
On Behalf Of Charrondiere, Ruth (ESN)

Sent: maandag 10 november 2014 15:50

To: 
[log in to unmask]

Subject: Re: Inquiry about vitamin A activity in cis-beta carotene


 
Dear all,
I looked up the IOM report of 2001 and found:
- 1 μg retinol activity equivalent (μg RAE) is equal to 1 μg all-trans-retinol, 2 μg of supplemental all-trans-β-carotene, 12 μg dietary all-trans-β-carotene,
 and 24 μg other dietary provitamin A carotenoids: α-carotene or β-cryptoxanthin. However, this is very often reported as: 1 μg retinol activity equivalent (μg RAE) is equal to 1 μg retinol, 12 μg β-carotene, and 24 μg other dietary provitamin A carotenoids:
 α-carotene or β-cryptoxanthin –assuming that everyone knows that we refer to the all-trans forms.


- Of the many carotenoids in nature, several have provitamin A nutritional activity, but food composition data are available for only three (α-carotene, β-carotene,
 and β-cryptoxanthin) (Figure 4-1). The all-trans isomer is the most common and stable form of each carotenoid; however, many
cis isomers also exist.
 
In most of the text, only β-carotene is mentioned – no differentiation between cis and all-trans forms.

 
Also FAO/WHO does not specifically mention cis-β-carotene, but in most cases referes to simply β-carotene, meaning in most cases all-trans-

β-carotene. 
 
Therefore Miyuki asked the question. I can see that some interpret IOM and FAO/WHO as if cis- β-carotene should have half of the vitamin A activity of all-trans-β-carotene.
 
In my view, we would need to come up for a common approach for dealing with the cis forms of β-carotene, α-carotene and β-cryptoxanthin.

 
Thus my questions:
- are the cis forms of β-carotene, α-carotene and β-cryptoxanthin analysed – of β-carotene the answer is yes
- should the cis forms of β-carotene, α-carotene and β-cryptoxanthin have half of the vitamin A activity of their all-trans counterparts?
- which data would support the vitamin A activities of the cis forms of β-carotene, α-carotene and β-cryptoxanthin – and at which level?
 
Thanks for all your replies
 
Best wishes
Ruth
 
From: Food Composition Discussion Group [mailto:[log in to unmask]]
On Behalf Of [log in to unmask]

Sent: 07 November 2014 12:12

To: 
[log in to unmask]

Subject: Re: Inquiry about vitamin A activity in cis-beta carotene


 

Dear Miyuki,
 
Cis β-carotene isomers present provitamin A activity.
We can see in the Recommended Dietary Allowances and in the Dietary reference intakes that we should calculate Retinol Equivalents (RE) and Retinol Activity Equivalent (RAE) according
 to the following conversion factors:
RE = 1 μg all-trans
retinol + 1/6 μg of dietary all-trans β-carotene + 1/12 μg of other dietary provitamin A carotenoids (NRC, 1989);
RAE = 1 μg all-trans
retinol + 1/12 μg of dietary all-trans β-carotene + 1/24 μg of other dietary provitamin A carotenoids (IOM, 2001).
So we can read that cis β-carotene isomers should use the conversion factors for "other dietary provitamin A carotenoids”. In Brazil we decided to adopt this approach when data for cis
 isomers is available.
 
References:
(NRC) National Research Council (1989). Committee on Dietary Allowances. Recommended Dietary Allowances: 10th Edition. Washington, DC. Retrieved August 18, 2014 from:

http://www.nap.edu/openbook.php?isbn=0309046335
(IOM) Institute of Medicine (2001). Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium,
 and zinc. Washington, DC: National Academies Press. 
 
Best regards,
 
Fernanda Grande
 
Department of Food and Experimental Nutrition
Faculty of Pharmaceutical Sciences
University of São Paulo (USP), São Paulo, SP, Brazil
Av. Prof. Lineu Prestes, 580 - Cj. Químicas Bl.14
CEP 05508-900 São Paulo - Brasil
Tel: +55 11 99225 0576
 

 

 




De:
"Miyuki Shimizu" <[log in to unmask]>

Para: [log in to unmask]

Enviadas: Terça-feira, 4 de Novembro de 2014 8:08:51

Assunto: Inquiry about vitamin A activity in cis-beta carotene

Dear, all,
 
I’m an intern working at the nutrition division at FAO. I’m currently working on the food biodiversity database for cassava crop. In the following  paper, the retinol
 equivalents are calculated based on the total values of all-trans-beta carotene and cis-beta carotene.
(Reference:

http://pubs.acs.org/doi/abs/10.1021/jf5018302) 
 
I’m trying to figure out the metabolism of cis isomer of beta carotene, whether it has vitamin A equivalent activity. All-trans-beta carotene is the most suitable precursor
 for vitamin A, but several studies have provided the evidence that 9-cis-beta carotene is a precursor of 9-cis retinal or retinoic acid. As far as I know, there is little evidence that 9-cis-beta carotene is found in human plasma
 since cis-beta carotene is isomerized to all-trans beta carotene after its oral administration.

 
I would highly appreciate if someone can share their information/data/experience regarding the vitamin A activity of cis-beta carotene:

- For VITA in retinol activity (RE) should 9-cis-beta carotene have: 1/6 or 1/12 or 0 vitamin activity?
- For VITA_RAE should 9-cis-beta carotene have: 1/12 or 1/24 or 0 vitamin activity?

Could you also then provide your source of evidence?
 
Thank you in advance for your attention to this matter.  
 
Reference:

Beta-Carotene:
 The Controversy Continues. 
http://www.altmedrev.com/publications/5/6/530.pdf
Evidence of cis-trans isomerization of 9-cis-beta-carotene during absorption in humans.
http://ajcn.nutrition.org/content/64/2/177.short
 
Best regards,
Miyuki Shimizu, MS, RD
Nutrition Intern
Food and Agriculture Organization of the United Nations (FAO)
Nutrition Education and Consumer Awareness Group (ESNE)
Nutrition Division (ESN)
Viale delle Terme di Caracalla, 00153
Rome, Italy
Room : B246
Tel.: +39 06570 55899
Website :
http://www.fao.org/food/en/

 



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