Volume 56 Number 45
                    Produced: Tue Sep 23 21:40:07 EDT 2008

Subjects Discussed In This Issue: 

Eating fish and meat (3)
         [Eitan Fiorino, Yechiel, Batya and Yisrael Medad]


From: Eitan Fiorino <afiorino@...>
Date: Mon, 22 Sep 2008 09:50:40 -0400
Subject: RE: Eating fish and meat

The exchange between myself and Dr. Backon has gotten somewhat testy.
For me, overstated conclusions drawn from scant data strike a particular
nerve, as this was an issue I constantly dealt with my during my years
on Wall Street investing in biotechnology companies, and is something I
must be very vigilant about in my current role directing the clinical
development of a drug - so maybe I am a little touchy on the subject.
Moreover, in a forum such as this, in which we discuss the halachic
ramifications of science, I think all claims must be subjected to the
most rigorous scrutiny and criticism.  In case there are any doubts, I
want to state for the record that I have no personal animus against
Dr. Backon, nor is it my intent to insult him.  I will redouble my
efforts to insure that my comments are directed at his claims, arguments
and assumptions and not at his person.  Because I believe the stakes are
high, however, I will not hesitate to point out flaws in his evidence !
and arguments.

> 1. Dr. Katz had mentioned that the halachic prohibition of eating meat
> and fish (SIMULTANEOUSLY) is "faulty medicine".

> 2. I countered by mentioning some older work (late 1980's and early
> 90's) that fish oil IN SOME CASES paradoxically increased incidence of
> psoriasis.  I also mentioned the very ancillary material on lipid
> abnormalities in psoriasis.  [I shouldn't have mentioned it at all as
> it was basically irrelevant]

> 3. Dr. Fiorino, instead of discussing the adverse effects of
> SIMULTANEOUS EATING of dietary fish oil with dietary stearic acid from
> beef, simply stated that psoriasis is a T-cell abnormality, harped on
> my ancillary comment on lipid abnormalities in psoriasis, and
> completely ignored the issue at hand: simultaneous ingestion of fish
> with beef.

For the record, the statement of Dr. Backon that I found so
objectionable was his claim that:

    There actually **is** an adverse affect between stearic acid (in
    beef) and omega-3 in fish inducing lipid peroxidation and formation
    of free radicals.

This was in fact the ONLY statement upon which I commented on in my
first posting.  In ommiting this from his reconstruction of our
exchange, and by asserting that I "completely ignored the issue at hand:
simultaneous ingestion of fish with beef," he distorts and misrepresents
my comments.  Dr. Backon also claims that I "harped on" some "ancillary
comment on lipid abnormalities in psoriasis."  This too is incorrect -
my entire posting was in fact centered upon his central claim, that
eating meat and fish together has an adverse medical consequence.  His
central claim can hardly now be said to have constituted "ancillary

I have to point out that Dr. Backon has yet to submit any evidence in
support of his theory.  This was the entire point of my critique - as I
wrote in the first posting, I was not claiming to have completed a
literature review, but rather was presenting a methodoloogical critique.
Dr. Backon is free to hypothesize all he wants about the dangers of
simultaneous consumption of meat and fish, but if he is going to claim
that such dangers are a fact and have been proven to exist AND tell all
of us to draw halachic conclusions from his assertion, well then he
better cite some studies that prove this (and he better expect to have
his claims challenged and tested).  The idea of supporting a claim about
a medical intervention with prospectively collected clinical data is a
basic tenet of evidence-based medicine and I wonder why Dr. Backon is
not able or not willing to apply those tenets to this question.

> 4. I calmly suggested to the laypeople on MAIL JEWISH to access the
> website http://scholar.google.com  and key in the terms "psoriasis
> dietary lipids" where they would see hundreds of journal references to
> T-cell signalling and the immune response being affected by specific
> dietary lipids
> 5. Instead of letting the issue rest, Dr. Fiorino ignores the above
> (T-cell signalling and the immune response being affected by specific
> dietary lipids) and posts a very insulting and demeaning reply
> ("meaningless fact", "utterly beside the point". "Illusory nature",
> "garbage"). . . .

The implication of Dr. Backon's invitation to the Mail-Jewish readership
to perform a Google Scholar search, whether he intended it or not, was
clear: to suggest to the readers (the vast majority of whom are very
unlikely to be able to critically assess the complex medical and
scientific literature about dietary lipids) that the mere existence of
thousands of references to psoriasis and dietary lipids is, in itself,
support for his position.  After all, this was Dr. Backon's reply to my
request for evidence to support his hypothesis.

I don't understand why I ought to have "let it rest" at that (aside from
considering the likelihood that most Mail-Jewish readers couldn't give a
hoot about this discussion!).  Should I have conceded "good point, maybe
there is something here, I guess Chazal were right?"  On the contrary!
From my perspective it was important to point out that in fact many
diseases have considerably more citations when searched in conjunction
with the phrase "dietary lipids."  Therefore I stand by my statement
that the number of references turned up on a Google Scholar search is
both "beside the point" and a "meaningless fact," particularly in this
context and especially when Dr. Backon himself has characterized
elements of his own initial contribution as "basically irrlelevant."

I will also note for the record that I called the references I generated
with my own Google search ("psoriasis meat fish") as constituting
"garbage" and did not use that term to refer to anything Dr. Backon has
written, despite his lumping that term in with phrases I did use to
describe his points.

> 6.  If you had carefully checked the list of papers you would have
> noticed that eating hydrogenated fish oil [trans fats] (free radicals)
> has been etiologically linked to prevalence of psoriasis. The only
> question that needs to be answered (and it's a logical conclusion) is
> whether eating stearic acid (beef) WITH fish (oil) can induce this
> type of partial hydrogenation. In other words, will the unsaturated
> fatty acid convert into a saturated fatty acid. To the best of my
> knowledge, this topic has never been addressed.

I remain flabbergasted.  I simply fail to see anything in the literature
 that could be described as evidence supporting what Dr. Backon claims.
 I have searched both Medline and Google Scholar for references relating
 to hydrogenated fish oil and the etiology of psoriasis, or psoriasis in
 general, and find nothing that seems to address the issue.  Thus I am
 not able to find any support for Dr. Backon's statement that "eating
 hydrogenated fish oil [trans fats] (free radicals) has been
 etiologically linked to prevalence of psoriasis."  Moreover, I am not
 clear how this particular statement relates to his original claim,
 which was that "there actually **is** an adverse affect between stearic
 acid (in beef) and omega-3 in fish inducing lipid peroxidation and
 formation of free radicals."  I am by no means a lipid chemist, but as
 far as I know the oils found naturally in fish are not hydrogenated,
 but both fish and vegetable oils are hydrogenated by the food industry
 in order to al!  ter certain properties, for example, to make them
 solid at room temperature and thus allow them to be used in margarine
 and shortening.  If this is correct, then surely Chazal could not have
 had in mind "hydrogenated fish oils" when they stated it is dangerous
 to comsume meat and fish together.

Now I have found some medical literature that IS relevant to at least
the fish half of the question - there are a number of studies on the use
of fish oil supplements in treating psoriasis.  It turns out that fish
oil supplements, administered orally in prospective, randomized clinical
trials, have by and large not shown any effect at all in psoriasis.  For
example, the conclusion of a clinical trial published in the New England
Journal in 1993: "Dietary supplementation with very-long-chain n-3 fatty
acids was no better than corn-oil supplementation in treating
psoriasis."  A 2005 paper in the British Journal of Dermatology
(M. Wolters, "Diet and Psoriasis: Experimental Data and Clinical
Evidence," full text available on Medscape) reported that of four
randomized, controlled studies of oral fish oil supplements in
psoriasis, only one showed any benefit for fish oils while the others
showed no effect.

So, getting back to the beginning - we have a statement by Chazal about
the danger involved in eating meat and fish together, and this danger
seems to be related to tzarat.  Some believe that what the Torah
describes as tzarat may in fact be psoriasis (though I can say I never
saw a patient who complained their psoriasis flared when they gossiped,
nor did I ever meet a patient who complained his house or clothes also
had psoriasis, so for me it is not so clear that tzarat is psoriasis).
The thesis we are examining is that simultaneous consumption of meat and
fish causes psoriasis or worsens it, owing to some kind of chemical
interaction between the lipids found in beef and those found in fish.
We now know that fish oil supplements (an imperfect but reasonable proxy
for fish in this context) appear to have no impact on psoriasis, or
possibly some modest benefit, but uunfortunately we have no idea what
impact beef consumption might have on psoriasis as that question has
neve!  r been studied, at least not propectively.  Thus, at this point
the theory needs to accommodate the facts and specify how, when meat and
fish are consumed together, there is some kind of unique interaction
that results in a pro-psoriatic effect that we know is not present when
fish alone are eaten (and that presumably is not present when meat alone
is eaten, since Chazal did not warn up of there being a danger with
either meat or fish alone).  I should add that this theory must also
account for the fact that this meat-fish interaction occurs only when
they are eaten simultaneously, but not if they are consumed separated by
very short intervals.  Finally, the theory must account for the fact
that millions of people (including Jews) across the globe consume meat
and fish together on a regular basis without developing psioriasis or
experiencing worsening psoriasis.

> 7. All you need to show that the "halacha is faulty medicine"
> is to ask experts in lipid biochemistry whether saturated fats in a
> piece of beef (steak, burger, brisket) plunked in fish oil will cause
> inhibition of delta-6-desaturase in the liver [which would then
> explain the lipid abnormalities in psoriasis].

On the contrary, there are MANY questions that remain about the claim
under scrutiny here.  For even if we assume that beef "plunked in fish
oil will cause inhibition of delta-6-desaturase in the liver," many
other critical questions remain unanswered including (1) does the effect
happen only during consumption of meat and fish but not during
sequential consumption? (2) does the effect produce measurable clinical
consequences that can be detected in a randomized, controlled clinical
trial, in particular does it cause or worsen psoriasis? and finally, (3)
is psoriasis indeed tzarat?

I think Dr. Backon and I must simply agree to disagree with regard to
the quality of evidence supporting his theory, and leave the rest of you
to ponder this yourselves.


From: <jeremy.conway@...> (Yechiel)
Date: Sun, 21 Sep 2008 13:30:59 +0100
Subject: Eating fish and meat


Russell Hendel states that the sakkanah (danger) involved in eating fish
and meat together is the fear that bones might become stuck in one's
throat and that all that needs to be done to avoid this danger is to use
separate plates.

IMHO, the first statement is incorrect and the second is incomplete.
As regards the first statement, the Talmud states that the danger of
eating fish and meat together is that it might cause tzara'at (often
incorrectly translated as leprosy.  Possibly a spiritual ailment rather
than a physical one.) 

As regards the second statement, it is true that separate crockery and
cutlery are required unless they are throroughly washed and dried
between the fish and meat courses.  In addition, however, kinuach
(cleansing of the palate with a hard solid food such as bread or cake)
and hadacha (rinsing the mouth by drinking water, wine or liquor - hence
the custom to drink a lechaim between the two courses) are required. 
As an aside, it is interesting to note that in the case of fish and
MILK, many Ashkenazi poskim (including the Chatam Sofer if I'm not
mistaken) are happy to be lenient in the light of medical opinion.
Indeed, at least one posek points out that the Rambam, whom he describes
as the greatest of the doctors, permits fish and milk to be cooked
together.  Both the Shach and the Taz explain that Rabbi Yosef Caro's
apparent reference to fish and milk is the result of a copyist's error. 

Ketiva vachatimah tovah.


From: Batya and Yisrael Medad <ybmedad@...>
Date: Sun, 21 Sep 2008 14:54:16 +0300
Subject: RE: Eating fish and meat

I can't accept your disease, bones, etc reason for the Halacha for two
main reasons:

 1. Once you give "scientific" reasons, you make it possible to cancel
    the halach once technology, medicine etc finds a cure.  That's like
    the Jews who say that refrigeration makes kashering meat passe`.

 2.  It's an Ashkenaz psak, and the halachot come from that.  Sfardim
    don't separate the same way and have fish immediately after meat,
    without changing forks etc.  They consider fish more like poultry. 
    Actually some consider cream cheese and lox comparable to a
    cheeseburger.  I have a feeling I posted this a few years ago.  One
    of the first Jerusalem bagel places, The Bagel House, had trouble
    getting rabbinic approval, because the mashkiach sent was Moroccan.

Batya Medad
http://www.israelnationalnews.com/Blogs/Blog.aspx/6  (The Eye of the


End of Volume 56 Issue 45