Darwin-L Message Log 8:103 (April 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

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<8:103>From phlkcs@gsusgi2.gsu.edu  Thu Apr 28 06:00:24 1994

Date: Thu, 28 Apr 1994 06:51:54 -0400 (EDT)
From: "Kelly C. Smith" <phlkcs@gsusgi2.gsu.edu>
Subject: Re: Vitamin C
To: darwin-l@ukanaix.cc.ukans.edu

On Wed, 27 Apr 1994, JOHN LANGDON wrote:

> Loss of an expensive metabolic pathway from lack of need may
> or may not result from natural selection-- the charges of
> Lamarckianism are unfair.

Absolutely true.

> However, there may be another
> explanation. Many vitamins are toxic in excessive doses-- e.g.
> hypervitaminosis A is lethal.

Is hypervitaminosis _A_ (as opposed to D) lethal? I have not heard of
this.  If so, it would take truly massive doses since there are many
people who have been taking 50,000 IU for twenty years with no
appreciable side effects.

> I have read that excess vitamin
> C has side effects such as diarrhea. Can anyone elaborate on
> this?

This does occur if one takes enough C (which is not all bad - C is one
of the cheapest, fastest and most effective laxatives you can get).
The amount required depends on one's individual tolerance as well as
whether there is any stress on the immune system (when the immune
system is stressed, bowel tolerance increases - intriguing circumstantial
evidence of an important role for C in immune response).  However, the
vast majority of people can take at least a gram of C a day with no ill
effects.  It seems unlikely to me (though I have no evidence to support
this) that a fructivorous diet would result in more than 1 gram of C
intake a day (even adding in the ancestral synthesis).  Moreover, if we
are going to hypothesize that our ancestors lost the capacity to
synthesize C, it seems likely that our tolerance (ability to metabolize)
C decreased commensurately.
Kelly Smith

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