Re: Carbs and Cholesterol.

On Fri, 26 May 2006 22:09:47 +0300, "Juhana Harju"
<shantigiriorama@xxxxxxxxx> wrote:

Matti Narkia wrote:
: On Fri, 26 May 2006 19:04:43 +0300, "Juhana Harju"
: <shantigiriorama@xxxxxxxxx> wrote:
:: Jim Chinnis wrote:
::: "Juhana Harju" <shantigiriorama@xxxxxxxxx> wrote in part:
:::: Matti Narkia wrote:
::::
::::: This brings to my second point: although canola oil (or more
::::: generally rapeseed soil) due to its omega-3 content has a benefit
::::: of inhibiting postparandial vasoconstriction, it may also have
::::: some risks (increased prostate cancer risk, toxic subtances
::::: produced from alpha-linolenic acid in cooking) attached to it. It
::::: seems that a similar benefit, but without risks, can be obtained
::::: with olive oil + (fatty fish OR fish oil supplement at meal time).
::::
:::: Consider the effects of the Lyon Diet Heart Trial where heart
:::: disease incidense decreased by 70%. An important element in the
:::: trial was the use of rape seed oil based margarine containing
:::: alpha-linolenic acid.
:::
::: Other important differences include lower carbs, higher fat, less
::: red meat, more fish, more fruit, and more vegetables. The
::: comparison was between a modified (AHA "prudent") American diet and
::: a modified Cretan diet.
:::
::: It may well be the case that the ALA is responsible for 40% of the
::: improvement, but no one really knows.
::
:: Here is an interesting meta-ananalysis - although the average
:: reduced risk is only 21%.
::
:: J Nutr. 2004 Apr;134(4):919-22.
:: Dietary alpha-linolenic acid is associated with reduced risk of fatal
:: coronary heart disease, but increased prostate cancer risk: a
:: meta-analysis. Brouwer IA, Katan MB, Zock PL.
:: Wageningen Centre for Food Sciences, Wageningen, the Netherlands.
::
: 21% is probaly not far from truth, IMHO. The study
:
: Singh RB, Niaz MA, Sharma JP, Kumar R, Rastogi V, Moshiri M.
: Randomized, double-blind, placebo-controlled trial of fish oil and
: mustard oil [...]
: If you calculate the ratios, it seems that fish
: oil reduced cardiac events by 29.4% and ALA by 19.3%. Moreover, total
: cardiac deaths showed no significant reduction in the mustard oil
: group; however, the fish oil group had significantly less cardiac
: deaths compared with the placebo group (11.4% vs. 22.0%, p < 0.05).
: Again calulating the ratio you get 48.2 reduction in cardiac deaths by
: fish oil! I'm not sure whether calcuting ratios this way is the
: correct way to estimate reductions, but at least it gives a rough
: idea. Perhaps Jim Chinnis could comment on this?
:
: So on today's evidence it seems fair to say that 2-3 g of ALA/d may
: reduce cardiac events and mortality by about 20%, which is probably
: slightly less than what can be achieved with fish oil, IMHO.

I am not very happy with this comparison.

The best way to compare two treatments is to compare them in the same
controlled clinical study as was done in the above study.

But of course we cannot rely on this study alone.

I think we would get a more
accurate picture by comparing the previous ALA meta-analysis to the
available fish oil meta-analysis.

It could give some prespective, but it's not the best way to compare
two different treatments. For the most accurate picture of efficacy
differences of two treatments, they have to be compared in the same
trial. That's how it's done for drugs, too.

That comparison reveals that there is no
advantage in fish oils over ALA. (Still I would like to add that this is not
an either/or question as ALA and fish oils are both beneficial and
complementary in their effetcs.)

Which fish oil meta-analysis did you have in mind?

: See also
:
: Oomen CM, Ocke MC, Feskens EJ, Kok FJ, Kromhout D.
: alpha-Linolenic acid intake is not beneficially associated with 10-y
: risk of coronary artery disease incidence: the Zutphen Elderly Study.
: Am J Clin Nutr. 2001 Oct;74(4):457-63.
: PMID: 11566643 [PubMed - indexed for MEDLINE]
: <http://www.ajcn.org/cgi/content/full/74/4/457>
:
: In the landmark GISSI trial 1 g of long chain PUFAs (APE+DHA)
: decreased the risk of death 20%, risk of cardiovascular death 30% and
: risk of sudden death 45%, all of which were stastically significant.

You are now comparing one of the worst ALA studies to one of the best fish
oil trials. :-) Not very fair I would say. :-D

It was not a comparison. The comparison was made in the controlled
clinical trial by Singh et al. The dutch study was just an example
showing that alpha-linolenic acid may not work in every population. If
you read the study, you'll notice that the subjects were elderly men,
ages 64 to 84 years, and that the explanation for the result may be
that the participants may have got trans-fats in connection with
alpa-linolenic acid intake.

Similarly, a Norvegian CHD secondary prevention trial failed to show
benefit for 880 mg of ethylester concentrate of EPA+DHA over corn oil,
The reason was thought to be the relatively hy intake of fish by
Norwegians, fish oil did not bring any additional benefits:

Nilsen DW, Albrektsen G, Landmark K, et al.
Effects of a high-dose concentrate of n-3 fatty acids or corn oil
introduced early after an acute myocardial infarction on serum
triacylglycerol and HDL cholesterol.
Am J Clin Nutr. 2001; 74: 50?56
<http://www.ajcn.org/cgi/content/full/74/1/50>

Participants resided in a coastal area and all patients received a
diet rich in fish products, so they probably already had relatively
high EPA and DHA level before the study, and additional EPA+DHA did
not bring any benefits.

So it seems that both ALA and EPA+DHA may not bring benefit in all
populations.

There is a discussion of possible mechanisms, by which omega-3 fatty
acids may prevent CVD in

Kris-Etherton PM, Harris WS, Appel LJ; American Heart Association.
Nutrition Committee.
Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular
disease.
Circulation. 2002 Nov 19;106(21):2747-57. Erratum in: Circulation.
2003 Jan 28;107(3):512.
PMID: 12438303 [PubMed - indexed for MEDLINE]
<http://circ.ahajournals.org/cgi/content/full/106/21/2747>




--
Matti Narkia
.

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