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From: B. Harris)
Subject: Re: What does the D- mean- Ask your Phamacist?
Date: 4 Jul 1998 03:21:19 GMT

In <> Donald Cottman <>

> wrote:
>> I ordered some glucosamine sulfate through a reputable mail order
>> company that I often use. When I got the bottle and read it, it said
>> "each capsule contains: D-Glucosamine Sulfate."
>> I was a little p.o.ed as I ordered Glucosamine Sulfate.
>> Would someone please tell me what is the difference? No, I am not a
>> chemistry major, but I still would like to know!
>> You may e-mail me privately also if you wish.
>Hey monkey,
>If you had obtained that through a community pharmacy, rather than
>trying to save a few bucks, you would have had your answer immediately
>from the folks who sold it to you. If you are buying medications, and I
>count nurtritionals, herbals, ect. as such, that you don't really know
>about, I'd reccommend buying them from someone who probably does- YOUR


   Or, you could ask on the net, and cross your fingers that the person
who answers you knows what he or she is talking about <g>.  All
glucosamine on the market is, in fact, D-glucosamine, because it's all
made (commercially, and in your body, too) from glucose, which is all,
by definition, D-glucose (dextrose).  The D refers to the direction
polarized light is rotated through a solution of the stuff (dexter-- to
the right).  The L form is the mirror image, but it doesn't exist
naturally.   Anyway, like vitamin C, which is another chiral molecule
also produced both in animals, and commercially, from glucose, you
never get the wrong stuff (enantiomerically or chirally speaking) in
glucosamine, because they always start with the "right stuff"

   It has, in the past, been possible to buy some other nutrient
supplements in which you get both chiral forms (D and L, sometimes
shown as "dl" or "d,l"), because the stuff is synthetic, and doesn't
start from a chiral starting chemical.  Examples are vitamin E,
carnitine, and phenylalanine.  In the case of carnitine, the unnatural
L form turned out to be mildy toxic, and was taken off the market.  In
other nutrients, no unnatural isomer has not been found yet to cause
any problems (there are claims, not well repeated, that the D form of
phenylalanine has special properties as a neurochemical). In a few
cases (D-methionine), the body is able to convert D to L, so synthetic
DL mixes are commonly used commercially without much worry.  In other
cases (vitamin E) you can take your choice of natural D (produced
mostly sythnetically from chiral starting materials, such as other E
vitomers), or fully synthetic stuff (d,l-alpha-tocopherols, which are
actually dl,dl,dl-alpha-tocopherols).

                                      Steve Harris, M.D.

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