8

votes

"poor" converters vs optimal converters

Answered on August 19, 2014
Created September 06, 2012 at 12:37 PM

How do we now if LOW conversion of ALA to DHA and beta carotene to retinol means POOR conversion... Couldn't it be optimal conversion? I have always beens suspicious of this, and there seems to be more and more evidence that having a proper ratio of vitamins is what is important, not the amount (ex. certain vitamins compete with one another- A and D).

I have always been curious about this, because it seems like consuming the plant forms of certain vitamins would be the SAFEST means of getting them and then allowing our bodies to convert what is necessary dictated by the rest of diet and the vitamin ratios in it. FOr instance assuming ceteris paribus, if Bradly eats 5g of ALA and converted 2 of it to DHA, and Audrey eats 8g of ALA and converts 2-y of it to ALA, they'll come out equal. And, ceteris paribus again, if Bradly eats 100mg of beta carotene and Audrey eats 200g of beta carotene, Brad may convert 50mg to retinal and Audrey converts 50mg-z of it retinol.

In other words, we insert the Brad and Audrey "only" converts x amount of plant vitamin to the animal form because it is not equivalent ex-poste (i.e. plant version is not converted to animal version on a 1-to-1 basis). However, this does not by any means imply it's not fully efficient or not optimal, it just means it's not 1-to-1. I haven't seen any evidence that it by necessity means it is not optimal. I'm sure there are perfectly healthy indigenous cultures who actually eat zero seafood, and yet have somehow survived healthily for thousands of years.

I hope I have explained myself adequately in a variety of ways so everyone gets it if they did not the first time. So, why do we assume that not 1-to-1 conversions of plant vitamin forms to animal vitamin forms means that we're "poor converters?" Maybe optimal is not 1-to-1 and is less than that and different for everyone based on the diet.**

For practical purposes, it does seem SAFER to consume plant vitamins and let our bodies determine the specific amounts and RATIOS that need to be converted over to animal form. Seems like a built in protection mechanism. This especially seems so since we are not carnivorous beings, and have things like a taste for sweet foods can develop toxicity from certain amounts of animal forms (retinol, for instance).

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on September 06, 2012
at 11:19 PM

@ Jamie: your answer strikes be as odd, because what you wrote after it makes it seem like you are stating something as a fact and then asking if it is or not.

Bb3d1772b28c02da2426e40dfcb533f5

(5381)

on September 06, 2012
at 10:32 PM

Ie theres a gene for more extensive conversion of ALA, LA etc.

Bb3d1772b28c02da2426e40dfcb533f5

(5381)

on September 06, 2012
at 10:32 PM

Some people are better converters than others based on their genes.

Fd70d71f4f8195c3a098eda4fc817d4f

(8014)

on September 06, 2012
at 08:36 PM

+1 for a damn good question.

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on September 06, 2012
at 02:22 PM

This is along the lines of what I was thinking. Thank you for the great response :)

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on September 06, 2012
at 02:20 PM

@raney, that's a very meat-centric view you have there! ;) We're hardly obligate carnivores so it makes little sense that our vitamin A should be coming solely from animal sources. Vitamin A is very much like vitamin D, given the proper inputs, we can make it ourselves.

0d0842381492a41b2173a04014aae810

(4875)

on September 06, 2012
at 01:32 PM

It seems more like a less efficient back-up mechanism to me, in case we weren't able to obtain meat for an extended period, or perhaps a biological remnant of how we obtained these nutrients from prior to adding meat to the diet. But +1 for questioning everything.

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1 Answers

5
32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on September 06, 2012
at 02:16 PM

From my chemist point of view, our bodies don't particularly like to keep around highly reactive things. DHA/EPA is a good example. They are less stable (thus more reactive), our bodies don't want a lot of these around, so it makes sense that conversion from ALA to DHA/EPA is on an as-needed basis. Retinol is toxic in high doses, so again it makes sense that conversion from beta-carotene is low to prevent toxicity problems.

The conversion is likely very dependent on a host of other factors. An important one being vitamin A status. If vitamin A sufficient, relatively little vitamin A is needed, thus conversion will be low. A diet rich in retinol will down-regulate enzymes that convert beta-carotene to retinol, so supplementing with beta-carotene will produce relatively little change in vitamin A status. If you eat a diet naturally low in retinol and high in beta-carotene, I'd venture a guess that your conversion is more efficient.

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on September 06, 2012
at 02:22 PM

This is along the lines of what I was thinking. Thank you for the great response :)

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