Cordain's reply to the vinegar questions:

Hi Rachel,
You are correct in questioning whether vinegar influences intestinal
permeability.  It is well established that disease, alcohol, non-steroidal
anti-inflammatory drugs, capsaicin derived from peppers (paprika, cayenne
etc) and dietary lectins (at high concentrations) may increase intestinal
permeability.   Some of this evidenc comes from human interventions -- some
from animal studies.

With vinegar, there is only animal data, and whether or not these
data can be translated to humans is still speculative.  Colitis
(inflammation of the colon) is routinely induced in rats by injecting acetic
acid (vinegar) into the rectum (Al-Awadi FM, Khan I. Blood purine and energy
status in rats with colitis. Dig Dis Sci 2001 Feb;46(2):443-8).   However,
the concentrations of acetic acid are a bit higher than the 5 % typically
found in vinegar.  Also, it is not known if ingested vinegar remains intact
through its passage from the stomach to the colon in humans at typical
dietary concentrations.

We believe that most of the interaction with the gut and the immune
system occurs not in the colon, but rather in the small intestine.
Suplhydryl compunds normally found in cells of the intestinal mucosa are
essential for maintaining intestinal integrity and preventing increases in
permeability.   Substances such as iodoacetic acid (a close analogue of
acetic acid) blocks sulphydryl compounds at a 2% concentration and causes
inflammation of the small intestine and increases in intestinal permeability
characteristic of Crohn's disease in animal models (Rachmilewitz D, Okon E,
Karmeli F. Sulphydryl blocker induced small intestinal inflammation in rats:
a new model mimicking Crohn's disease. Gut 1997 Sep;41(3):358-65.).  Whether
or not this series of events occurs in humans with vinegar in humans is not
known.

Most vinegar also contains yeast or residual proteins from yeast.
Yeast proteins contain multiple peptides that potentially may interact with
the immune system via 2 and/or 3 way molecular mimicry by virtue of
cross-reactive peptide sequences.  Whether or not yeast, or for that matter,
any other dietary food substance elicits or aggravates autoimmune diseases
in humans is still unknown.  The only exception to this is gluten (wheat,
rye, barley & maybe oats) and celiac disease and gluten and dermatitis
herpetiformis (a skin disease).

However, that being said, there is virtually no risk in removing
vinegar from the diet, and potentially many benefits, particularly for
people who may have autoimmune disease or gut related illnesses.  Clearly,
the evolutionary model of nutrition indicates that vinegar could not have
been consumed by pre-agricultural people, and yeast containing foods were
rarely if ever encountered.  I believe that we should follow the lead given
us by eon's of evolutionary wisdom.

You certainly can post this to the Paleo Food group to clear up this
issue.

Cordially,

Loren