Dear Pam
Thanks for noticing, and correcting, the typo.
Peter
----- Original Message -----
From: "Pamela Tom" <pdtom@ucdavis.edu>
To: "P Howgate" <phowgate@clara.co.uk>
Cc: "seafood" <seafood@ucdavis.edu>
Sent: Saturday, April 01, 2006 6:05 PM
Subject: Re: dissing omega 3 - correct web address for BMJ
> Dear Peter and Seafood Subscribers,
>
> Thank you for your excellent discussion in reply to the post by Liz Brown
> (Alaska Sea Grant marine advisor)!
>
> There is a typo in the url address for the British Medical Journal listed
> below. An "i" was substituted for one of the two "j"s in the domain
> address. The correct web address is http://bmj.bmjjournals.com/
>
> Pamela Tom
> Seafood HACCP Mailing List Owner
> University of California
> Sea Grant Extension Program
>
> On Sat, 1 Apr 2006, P Howgate wrote:
>
>> Dear Liz, and others
>>
>> This story questioning benefits of omega-3 oils appeared in the UK media
>> a
>> few days ago, but didn't 'run'. Your links refer to 2 though separate
>> topics, though there is a connection, and should be commented on
>> separately.
>> The first link, the British Medical Journal one, refers to an editorial
>> in
>> the journal which comments on a paper which questioned some claimed
>> benefits
>> the omega-3 oils and let me comment on that first.
>>
>> The paper is Hooper et al., 'Risks and benefits of omega 3 fats for
>> mortality, cardiovascular disease, and cancer: systematic review'. It has
>> not appeared in print yet, but a pdf file of it can be downloaded from
>> http://bmj.bmijournals.com .Go to the site and enter hooper and omega 3
>> into
>> the author and keywords boxes respectively in the top right and the paper
>> and its link to the pdf file will be listed. It describes a meta-analysis
>> of
>> a large number of studies of the risks and benefits stated in the title.
>> Their conclusion from this pooling and analysis of data was not the same
>> as
>> some previous meta-analyses, but those previous ones did not include the
>> results of a recent large study. Let me quote the conclusion from the
>> summary of the paper:"Long chain and shorter chain omega 3 fats do not
>> have
>> a clear effect on total mortality, combined cardiovascular events, or
>> cancer." Within the paper is an highlighted box which I assume was
>> inserted
>> in the editorial process to catch the eye of the skimming reader. Here is
>> what this box states under a subtitle 'What this study adds': "This
>> systematic review assessed the health effects of long chain and shorter
>> chain omega 3 fats (together or separately) on total mortality,
>> cardiovascular events, cancer, and strokes in a wide group of
>> participants
>> and found no evidence of a clear benefit of omega 3 fats on health" Note
>> that this editorial embellishment has changed the authors' '... do not
>> have
>> a clear effect on total mortality, combined cardiovascular events, or
>> cancer.' to '...found no evidence of a clear benefit of omega 3 fats on
>> health'. These 2 conclusions are not the same and that of the authors of
>> the
>> paper are more cautious and limited in scope than the editorial box
>> suggest.
>> The authors are quite explicit that they did not set out to examine
>> claims
>> for the health effects of omega-3 acids generally, but for some specific
>> aspects of health, mortality, cardiovascular disease and cancer.
>>
>> It is a highly technical paper directed towards epidemiologists and can
>> only
>> be appreciated by specialists, but the reasonably informed person can
>> follow
>> the discussion. The authors discuss at some length the recent survey
>> which
>> swung their meta-analysis towards a no effect compared with previous
>> analyses that did show an effect. The authors write in the section
>> Interpretation: "It is not clear whether long chain or short chain omega
>> 3
>> fats (together or separately) reduce or increase total mortality,
>> cardiovascular events, cancer, or strokes. Our findings do not rule out
>> an
>> important effect of omega 3 fats on total mortality, as robust trials at
>> low
>> risk of bias reported few deaths.". They also write: "UK guidelines
>> encourage the general public to eat more oily fish, and higher amounts
>> are
>> advised after myocardial infarction (supported by trials after myocardial
>> infarction). This advice should continue at present but the evidence
>> should
>> be reviewed regularly. It is probably not appropriate to recommend a high
>> intake of omega 3 fats for people who have angina but have not had a
>> myocardial infarction." These observations is not quite the clear-cut
>> conclusions put out in the media in Britain.
>>
>> The first link in Liz's message is to an editorial in The BMJ of 24 March
>> which is probably the source of the press release because the Hooper et
>> al.
>> is not yet published. Though called an Editorial it is more like a
>> scientific paper rather than an editorial in a newspaper in that it cites
>> references in a bibliography and is signed. After briefly summarising the
>> conclusions of the Hooper et al paper it goes on to discuss health
>> benefits
>> of consumption of omega-3 oils other than on cardiovascular conditions.
>> It
>> is the last paragraph that to my mind is incorrect and contentious; I
>> should
>> quote it in full: "We are faced with a paradox. Health recommendations
>> advise increased consumption of oily fish and fish oils, within limits,
>> on
>> the grounds that intake is generally low. However, industrial fishing has
>> depleted the world's fish stocks by some 90% since 1950, and rising fish
>> prices reduce affordability particularly for people with low incomes.
>> Global
>> production trends suggest that, although fish farming is expanding
>> rapidly,
>> we probably do not have a sustainable supply of long chain omega 3
>> fats.".
>> For the claim that the world's fish stocks have been depleted by some 90%
>> since 1950 the author cites a paper by Myers RA,& Worm B., 'Rapid
>> worldwide
>> depletion of predatory fish communities', Nature, 2003, 423:280-3. This
>> paper is not available at the Nature site unless you have a subscription
>> to
>> the journal, but can be downloaded from the Berkley university site at
>> http://seismo.berkeley.edu/~manga/eps3/myersandworm2003.pdf. This paper
>> though is about depletion of stocks of predatory fish, not of stocks of
>> fish
>> generally. Predatory fish are not fished directly for fish meal and oil
>> though both these products are obtained from wastes from processing of
>> predatory fish, for example meal from fillet waste, oil from livers. Most
>> fish oil is obtained from directed fisheries of pelagic fish. Over the
>> last
>> two decades or so the catch from industrialised fisheries has been around
>> 25-30 million tonnes/year other than in El NiZo years compared with about
>> 4
>> million tonnes of waste material going for reduction. FAO publishes on
>> bi-annual basis a "The State of World Fisheries and Aquaculture" and as I
>> read them they do not express great concern for the status of pelagic
>> stocks
>> caught for industrial purposes. It seems to me from my reading, though
>> without specialised knowledge of the subject, that there is a sustainable
>> supply of marine-sourced omega-3 fatty acids. What is up for discussion
>> whether or not this sustainable production is adequate for all
>> requirements,
>> and how much is to be used in animal feeds and how much for human
>> consumption.
>>
>> The author of the editorial has a point about affordability. In the UK
>> anyway, fillets, skin-on, of predatory white-fleshed fish such as cod
>> retails at around 20USD/kg, more expensive than chicken or of common cuts
>> of
>> pork or beef. Farmed salmon is slightly cheaper, about 17USD/kg. Salmon
>> is
>> very much richer in omega-3 acids than gadoids, fillets anyway, so farmed
>> salmon is a much better buy if omega-3 intake is of concern. Pelagic
>> fish,
>> herring and mackerel, on a fillet basis, are a little cheaper still, but
>> still more expensive than chicken or cheaper cuts of red meat. Official
>> health guidelines recommend that we consume one portion a week of fatty
>> fish. Assuming a portion is 150g of fillet and a world population of 6
>> billion, this would require 100 million tonnes live weight of oily, that
>> is
>> predominately pelagic, fish. Total world fishery production of all sorts
>> of
>> aquatic animals for all outlets, human consumption and for reduction, is
>> around 130 million tonnes, insufficient for all persons in the world to
>> have
>> one helping of fatty fish a week even if all the pelagic fish going for
>> reduction is diverted to human consumption. Now that is the paradox.
>>
>> Peter Howgate
>>
>> ----- Original Message -----
>> From: "Liz Brown" <bfeab@uaf.edu>
>> To: "seafood" <seafood@ucdavis.edu>
>> Cc: "Laine Welch" <msfish@alaska.com>; "Bristol BayTimes"
>> <bbtimes@nushtel.com>; "Victoria Briggs" <ViedeF97@aol.com>
>> Sent: Thursday, March 30, 2006 4:30 PM
>> Subject: dissing omega 3
>>
>>
>> > Here's the first 'not all it's cracked it up to be' story I've seen
>> > about
>> > omega 3:
>> > http://bmj.bmjjournals.com/cgi/rapidpdf/bmj.38798.680185.47v1?hrss=1
>> >
>> > Here's a link to the source for the assertion that we should stop
>> > eating
>> > fish because we've depleted the world's stocks:
>> > http://www.nature.com/nature/journal/v423/n6937/full/nature01610.html
>> >
>> > My knee jerk reaction is that this is irresponsibly ignoring that many
>> > fisheries are managed sustainably. I would be interested in hearing
>> > other
>> > perspectives.
>> >
>> > --
>> > Liz Brown
>> > Marine Advisory Program
>> > University of Alaska Fairbanks
>> > PO Box 1549
>> > Dillingham, AK 99576
>> > 907-842-1265
>> > Fax 907-842-3202
>> > www.uaf.edu/map
>> >
>> >
>> >
>> >
>>
>
>
>
>
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