Subject: Re: Questions about vitamins and enzymes from a novice.

From: Eric Armstrong <[email-masked]>
Date: Thu, 27 Jun 1996 11:49:49 -0700

Robert Laroussini wrote:
>
> 1.  Are all vitamins enzymes?
>I was surprised by one of the answers to your post.  My imperfect
recollection of Isaac Asimov's "Chemicals of Life" is that enzymes
are proteins, and vitamins are enzymes -- ones we can't make, which
makes them "vital".  This book is now out of print, although I was
able to find another copy in the first used book store I stepped into.
I'll have to double-check to be sure.  In the meantime, have you found
out anything more?

> 2.  Is it best to manufacture all vitamins using the cold processing
>     method?  I've been told temperatures above 108f kill enzymes,
>     thus are harmful to vitamins.
> I believe it was Howard in Enzyme Nutrition who wrote that enzymes are
denatured at 120 degrees or 140 degrees (again, I have to double-check).
At the same time, he says something about how that distinguishes them
>from  vitamins.  I didn't understand that comment, at first, but if
vitamins really aren't enzymes, it makes more sense.  Again, have you 
found out anything more?

P.S. Yes, over time, vitamins will degrade, depending on their storage
conditions and their chemical reactivity with air and light, and their 
response to heat.

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From: Eric Armstrong <[email-masked]>
Date: Thu, 27 Jun 1996 11:56:28 -0700

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From: [email-masked] (Chris & Jenny Ford)
Date: Fri, 28 Jun 1996 00:31:25 GMT

>conditions and their chemical reactivity with air and light, and their 

Vitamin C in particular is very unstable, and will break down rapidly
on exposure to light or heat. Cooked food has very little vitamin C,
which is why we are encouraged to eat FRESH fruit & veg. Reconstituted
fruit juices have lost most of their natural vitamin C, but
manufacturers often "top them up" with synthetic vitamin C.

If you've left your vitamin C tablet out on the bench for an hour, may
as well not take it. And if you bought it in a bottle you can see
into, even a brown one, you wasted your money, my friend ...

Jenny

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From: <[email-masked]> (G. Cote)
Date: 28 Jun 1996 15:29:46 GMT

In article <[email-masked]>, [email-masked] says...
>>     thus are harmful to vitamins.

Take it from an enzymologist - vitamins are not enzymes.  Vitamins are 
usually co-enzymes, or enzyme cofactors.  These are smaller, simpler 
molecules that are required by enzymes in order to be active.  Enzymes 
are proteins; vitamins are not.

Enzymes are inactivated by heat denaturation, but the exact temperature 
depends on the enzyme.  One enzyme may only have a half-life of a few 
minutes at 40C, while another may remain acitive for many hours at 90C.  
It depends on the particular protein structure.

Vitamins, like many other organic chemicals, will eventually change with 
time, exposure to heat, light, air, moisture, etc.

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From: Douglas Hawey <[email-masked]>
Date: Tue, 02 Jul 1996 10:35:22 +0000

> I'll have to double-check to be sure.  In the meantime, have you found
Well this has to be the first time I see Asimov cited as a ref. in
nutrition, and based on this posting I can see why. It is true
that enzymes are proteins. Vitamins on the other hand are more likely
to be used as co-enzymes at best. You might be surprised to know that
some of the compound we call vitamins can actually be made in the body,
a good example would be niacin, which can be made from tryptophan (an
essential amino-acid), provided some conditions are met. Also, not
all vitamins are necessarily used as co-enzymes, some show a rather
hormone-like activity (vit D). Good luck in locating the book as far as
collecting book goes but get your nutritional ref. from some other book.
Asimov??? C'mon!

Douglas Hawey
[email-masked]

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From: "Rafael Garcia" <[email-masked]>
Date: Thu, 4 Jul 1996 10:45:12 -0400

> into, even a brown one, you wasted your money, my friend ...

Just one thing to add...
Vitamin C is an antioxidant.  If you expose it to oxygen (overshaking your
orange juice) the vitamin is destroyed.  Like the lady said, fresh fruits
and vegetables are your best bet.

-- 
Rafael Garcia
Cornell Food Safety Laboratory

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From: [email-masked] (Jay Mann)
Date: 6 Jul 1996 11:16:42 GMT

Douglas Hawey ([email-masked]) wrote:
[snip]
: Well this has to be the first time I see Asimov cited as a ref. in
: nutrition, and based on this posting I can see why. 

Asimov taught in a dept of biochemistry early in his career and was very 
sound.  Don't blame him because a reader seriously mis-remembers or 
misunderstood an Asimov book.

Jay D Mann  <[email-masked]>
Christchurch, New Zealand

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From: Scott Filippino <[email-masked]>
Date: Sat, 06 Jul 1996 12:58:08 -0400

Hi.  I was wondering if someone sufficiently qualified could answer a 
question of mine.  As a bio major, I have some textbooks which say that 
the body cannot store amino acids, so all of the essential aminos must 
be obtained at the same meal (if they are to be used.)  On the other 
hand, I have a few nutritional books which address this issue (in an 
effort to convert the reader to a vegetarian, I must note) and say that 
the body does, in fact, maintain "amino acid pools" and that the idea 
that all of the essentials must be eaten at one meal is false.

I can appreciate the fact that my textbooks, as new as they are in terms 
of edition, may simply be citing older, disproven ideas.  However, I can 
also appreciate the fact that the nutritional texts I have may well 
simply be vegetarian propaganda, of which there seems to be plenty in 
existence.  I haven't a clue.

The question is: Who is right?  Does the body maintain amino acid pools 
or not?

Would anyone with the proper background and recent qualification address 
this, please?  Thanks. :)