From: gts (gts_2000@yahoo.com)
Date: Thu Apr 17 2003 - 12:09:50 MDT
Ramez Naam wrote:
> From: gts [mailto:gts_2000@yahoo.com]
>> It's extremely likely that hominids have been eating
>> fermented fruits for millions of years. Also organisms in our
>> gut are producing alcohol constantly.
> Can you provide references for the two statements above? I haven't heard
> either of them before and would like to learn more.
My first statement comes from the basic observation that humans have always
scavenged for food, which would easily include scavenging the fermenting
fruits that lay on the ground. Other animals also eat those fermenting
fruits, and it's fairly certain that we learned what to eat largely by
watching other animals. (This reminds me... birds in the yard of the home in
which I was raised ate the fermenting berries from the surrounding bushes.
We suffered broken windows from birds flying under the influence.)
Concerning my second statement, I don't recall where I learned about alcohol
production by gut microbes. Some microbes help oxidize alcohol, while others
actually produce it. I'll need to do some research to find references. I do
recall actually seeing a scientific estimate of the number of ml's of
ethanol produced each day in the healthy human gut.
A quick search of Medline turns up two relevant abstracts, which I have
included at the bottom of this post.
In the first abstract you'll find the statement, concerning aerobic bacteria
in the human colon, "Kinetic characteristics of the bacterial enzymes may
enable some of them to produce acetaldehyde even from endogenous ethanol
formed by other bacteria via alcoholic fermentation." In the second abstract
you'll find the statement "The effect of temperature on microbial
fermentation in blood was studied. Specimens of human blood from a blood
bank were inoculated with Candida albicans, an organism capable of causing
fermentation." Candida albicans is found also in the gut.
> Very interesting theory on prehistoric alcohol use though.
> The consensus among anthropologists is that every human
> culture yet studied has used chemical or ritual means to
> intentionally explore mental states (e.g., "get high"), so if
> there was some easy way for our hunter-gatherer ancestors to
> extract alcohol from the environment, it wouldn't be too
> surprising for them to find and make use of it.
Yes. I don't suppose our early ancestors started out intentionally to get
high, but it very likely happened as an occasional consequence of eating too
much fermenting fruit picked up off the forest floor. Some clever late paleo
or early neo guy then made the connection between fermented fruit and
pleasurable feelings, and on that day wine was born into the world. A little
later some neolithic guy noticed the same can be done with grains, and on
that day beer was born. Distilled spirits did not however come until much,
much later.
From a paleodiet perspective, a glass of wine with dinner is perfectly
acceptable and probably even beneficial, but shots of whisky are completely
out of the question.
-gts
ABSTRACT:
Characteristics of alcohol dehydrogenases of certain aerobic bacteria
representing human colonic flora.
Alcohol Clin Exp Res 1997 May;21(3):489-94 (ISSN: 0145-6008)
Nosova T; Jousimies-Somer H; Kaihovaara P; Jokelainen K; Heine R; Salaspuro
M
Research Unit of Alcohol Diseases, University Central Hospital of Helsinki,
Helsinki, Finland.
We have recently proposed the existence of a bacteriocolonic pathway for
ethanol oxidation [i.e., ethanol is oxidized by alcohol dehydrogenases
(ADHs) of intestinal bacteria resulting in high intracolonic levels of
reactive and toxic acetaldehyde]. The aim of this in vitro study was to
characterize further ADH activity of some aerobic bacteria, representing the
normal human colonic flora. These bacteria were earlier shown to possess
high cytosolic ADH activities (Escherichia coli IH 133369, Klebsiella
pneumoniae IH 35385, Klebsiella oxytoca IH 35339, Pseudomonas aeruginosa IH
35342, and Hafnia alvei IH 53227). ADHs of the tested bacteria strongly
preferred NAD as a cofactor. Marked ADH activities were found in all
bacteria, even at low ethanol concentrations (1.5 mM) that may occur in the
colon due to bacterial fermentation. The Km for ethanol varied from 29.9 mM
for K. pneumoniae to 0.06 mM for Hafnia alvei. The inhibition of ADH by
4-methylpyrazole was found to be of the competitive type in 4 of 5 bacteria,
and Ki varied from 18.26 +/- 3.3 mM for Escherichia coli to 0.47 +/- 0.13 mM
for K. pneumoniae. At pH 7.4, ADH activity was significantly lower than at
pH 9.6 in four bacterial strains. ADH of K. oxytoca, however, showed almost
equal activities at neutral pH and at 9.6. In conclusion, NAD-linked alcohol
dehydrogenases of aerobic colonic bacteria possess low apparent Km's for
ethanol. Accordingly, they may oxidize moderate amounts of ethanol ingested
during social drinking with nearly maximal velocity. This may result in the
marked production of intracolonic acetaldehyde. Kinetic characteristics of
the bacterial enzymes may enable some of them to produce acetaldehyde even
from endogenous ethanol formed by other bacteria via alcoholic fermentation.
The microbial ADHs were inhibited by 4-methylpyrazole by the same
competitive inhibition as hepatic ADH, however, with nearly 1000 times lower
susceptibility. Individual variations in human colonic flora may thus
contribute to the risk of alcohol-related gastrointestinal morbidity, such
as diarrhea, colon polyps and cancer, and liver injury.
ABSTRACT:
Forensic Sci 1989 Jan;34(1):105-9 (ISSN: 0022-1198)
Chang J; Kollman SE
PharmChem Laboratories, Menlo Park, CA.
The effect of temperature on microbial fermentation in blood was studied.
Specimens of human blood from a blood bank were inoculated with Candida
albicans, an organism capable of causing fermentation. A preservative was
added to a portion of the inoculated specimens. These inoculated specimens,
as well as uninoculated blood, were stored under various temperature
conditions. Production of ethyl alcohol was monitored over a period of six
months. Fermentation was found to be highly temperature dependent, with
refrigeration proving to be most effective at inhibiting ethanol formation.
> For that reason, I'd be cautious about over-interpreting the
> presence of these enzymes as evidence for co-evolution of
> humans and alcohol consumption. That might be why the enzyme
> is there, or there might be some other reason(s).
>
> Very interesting theory on prehistoric alcohol use though.
> The consensus among anthropologists is that every human
> culture yet studied has used chemical or ritual means to
> intentionally explore mental states (e.g., "get high"), so if
> there was some easy way for our hunter-gatherer ancestors to
> extract alcohol from the environment, it wouldn't be too
> surprising for them to find and make use of it.
>
> cheers,
> mez
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