<<Disclaimer: Verify this information before applying it to your situation.>>

(This one is very long, but worth reading I think.  She also included  some
interesting attachments that I can email to anyone who is interested. I  will
have to break this response into parts so that it can be posted. --  Sherri)
I can't address how long your Mom to should eat wheat for a biopsy, but I
can tell you about our experience and discuss the statistics involved.  I'm
sorry this is long, but if someone had written me this email 15 months ago, my
daughter would not have gotten badly hurt, apparently from an unwise gluten
challenge.  I include footnotes to research at the end of the letter.

Statistics:

According to the 5 year study done by Alesio Fasano and many others,  only
ONE person in 56 tested, all who have known symptoms of  gluten intolerance will
actually obtain a positive biopsy proven celiac  diagnosis.  (Footnote # 1)

However, anecdotal experience shows that a number of those 55  symptomatic
but negative testing patients may still find that their  symptoms improve or go
away on a GF diet.  Unfortunately, many people do  not realize this, give up
when they receive a negative test, and don't check out  the diet for
themselves.

Others of the 55 already gluten free will try a challenge because "now they
can get the magic diagnosis and validation they have wanted for so  long"
They will be certain that if only their miserable challenge is long  enough, they
will get the 1 in 56 celiac label because they are already diet  proven.
They think that if you are not able to eat gluten, then you are  necessarily
"celiac".

Right now the chances that your mother can benefit from the  diet appear to
be 100% because she has already improved, if in fact  the improvement is due to
the GF diet.

If her improvement was due to the removal of gluten from her diet, then
resuming gluten in her diet for diagnostic purposes has a high chance  of
reinjury.  In fact, the purpose of the gluten challenge is to  reinjure so the injury
can be proven.

No one really knows how long it takes on a gluten challenge before  villi
damage may show for each individual.  Some researchers (Footnote  # 2) even claim
the damage may happen elsewhere first, and maybe  later or perhaps not ever,
to the villi.  It has become  obvious to many in the gluten intolerant
community that "villi damaged celiac  disease" is only one subset of "gluten
intolerance or sensitivity", depending on  their definition of "an unhealthy reaction
to gluten".  (One of these  researchers is still in the process of validating
his findings.   See quote from Marsh in the footnote at the end of this letter)

So the patient trades a known 100% success rate on the diet for a 1 in 56
chance of diagnostic success by current (narrow) medical standards, and accepts
a high chance of injury in the process.  There is no guarantee  that the body
will not be unusually sensitized by the challenge or that the  reinjury will
thoroughly heal after the GF diet is resumed.

*Support summarization of posts, reply to the SENDER not the CELIAC List*