Re: Omega-3 PUFAs from fish and fish oil do not increase oxidative stress nor lipid peroxidation (Re: Kidney stones and diet)

Taka wrote:

They should also use the "newest" methods of measuring the so called
AGEs such as HbAc1 which may be mediated by PUFA peroxidation. The
arachidonic acid (AA) metabolism activated by stress leads to more
free radicals than the spontaneous oxidation of Omega-3 PUFAs.
Therefore when we supply Omega-3 LC-PUFAs to AA-overloaded subjects
(which the american post menopausal women certainly are) we see a
decrease in oxidative stress because the LC-PUFAs suppress the AA-
induced chronic inflammation. All this is "beneficial" only short
term though ...

Because you say so? I don't think so. That is just empty and futile
speculation without any evidence whatsoever.

The bottom line is that

1) Studies show that fish and fish oil do not increase oxidative
stress nor lipid peroxidation, but may even reduce them.

2) Studies show that benefits of eating fish outweigh risks.

3) Studies show that very high blood levels of marine-derived omega-3
fatty acids are are associated with lower level of atherosclerosis.

4) Studies show that eating fish regularly reduces cardiovascular and
all-cause mortality.

The most important point is that _eating fish regularly reduces
all-cause mortality_. That's a final decider, which you cannot
argue against. Here some evidence about above points:

Turunen AW, Verkasalo PK, Kiviranta H, Pukkala E, Jula A, Männistö S,
Räsänen R, Marniemi J, Vartiainen T.
Mortality in a cohort with high fish consumption.
Int J Epidemiol. 2008 Jun 25. [Epub ahead of print]
PMID: 18579573
<http://ije.oxfordjournals.org/cgi/content/abstract/dyn117>

"Background Our aim was to assess the mortality of fishermen and
fishermen's wives in Finland, presuming that the mortality
reflects their high consumption of contaminated fish.

Methods All Finnish fishermen, registered since 1980, were
identified from the Professional Fishermen Register (N = 6410),
and the fishermen's wives from the national population register
(N = 4260). The cohorts were individually linked with
cause-of-death data until 2005 at Statistics Finland.
The follow-up started in the year after the first registration
as a fisherman and at marriage (if later) for the wives. The
standardized mortality ratios (SMRs) were calculated based
on the national mortality rates. In addition, blood samples
and food frequency questionnaire data were collected from a
volunteer sample.

Results The average fish consumption and serum concentrations
of fish-derived fatty acids and environmental contaminants
were higher among the fishermen and their wives than among the
general population from the same region. The fishermen and their
wives had lower mortality from all causes (SMR 0.78, 95% confidence
interval (CI) 0.73–0.82, and 0.84, 0.76–0.93, respectively), and
ischaemic heart diseases (0.73, 0.65–0.81, and 0.65, 0.50–0.83)
than the general population. Mortality from cerebrovascular
diseases and malignant neoplasms was decreased among the fishermen
(0.67, 0.52–0.85, and 0.90, 0.80–1.01), but not among the wives. In
addition, the fishermen's mortality from water transport accidents
was extremely high (8.31, 5.65–11.79).

Conclusions The fishermen and their wives had lower mortality from
many natural causes. The high intakes of environmental contaminants
in fish were not seen as excess mortality."


Mozaffarian D, Rimm EB.
Fish intake, contaminants, and human health: evaluating the risks and
the benefits.
JAMA. 2006 Oct 18;296(15):1885-99. Review. Erratum in: JAMA. 2007 Feb
14;297(6):590.
PMID: 17047219
<http://jama.ama-assn.org/cgi/content/full/296/15/1885>

"Context Fish (finfish or shellfish) may have health benefits and
also contain contaminants, resulting in confusion over the role of
fish consumption in a healthy diet.

Evidence Acquisition We searched MEDLINE, governmental reports,
and meta-analyses, supplemented by hand reviews of references and
direct investigator contacts, to identify reports published
through April 2006 evaluating (1) intake of fish or fish oil and
cardiovascular risk, (2) effects of methylmercury and fish oil on
early neurodevelopment, (3) risks of methylmercury for
cardiovascular and neurologic outcomes in adults, and (4) health
risks of dioxins and polychlorinated biphenyls in fish. We
concentrated on studies evaluating risk in humans, focusing on
evidence, when available, from randomized trials and large
prospective studies. When possible, meta-analyses were performed
to characterize benefits and risks most precisely.

Evidence Synthesis Modest consumption of fish (eg, 1-2
servings/wk), especially species higher in the n-3 fatty acids
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduces
risk of coronary death by 36% (95% confidence interval, 20%-50%;
P<.001) and total mortality by 17% (95% confidence interval,
0%-32%; P = .046) and may favorably affect other clinical
outcomes. Intake of 250 mg/d of EPA and DHA appears sufficient for
primary prevention. DHA appears beneficial for, and low-level
methylmercury may adversely affect, early neurodevelopment. Women
of childbearing age and nursing mothers should consume 2 seafood
servings/wk, limiting intake of selected species. Health effects
of low-level methylmercury in adults are not clearly established;
methylmercury may modestly decrease the cardiovascular benefits of
fish intake. A variety of seafood should be consumed; individuals '
with very high consumption (≥5 servings/wk) should limit intake of
species highest in mercury levels. Levels of dioxins and
polychlorinated biphenyls in fish are low, and potential
carcinogenic and other effects are outweighed by potential benefits
of fish intake and should have little impact on choices or
consumption of seafood (women of childbearing age should consult
regional advisories for locally caught freshwater fish).

Conclusions For major health outcomes among adults, based on both
the strength of the evidence and the potential magnitudes of
effect, the benefits of fish intake exceed the potential risks. For
women of childbearing age, benefits of modest fish intake,
excepting a few selected species, also outweigh risks."

Benefits of fish 'outweigh risks'
<http://news.bbc.co.uk/2/hi/health/6057732.stm>


Sekikawa A et al.
Marine-Derived n-3 Fatty Acids and Atherosclerosis in Japanese,
Japanese-American, and White Men.
J Am Coll Cardiol, August 5, 2008; 52:417-424,
doi:10.1016/j.jacc.2008.03.047
<http://content.onlinejacc.org/cgi/content/short/52/6/417>

"Objectives: We sought to examine whether marine-derived n-3 fatty
acids are associated with less atherosclerosis in Japanese versus
white populations in the U.S.

Background: Marine-derived n-3 fatty acids at low levels are
cardioprotective through their antiarrhythmic effect.

Methods: A population-based cross-sectional study in 281 Japanese
(defined as born and living in Japan), 306 white (defined as white
men born and living in the U.S.), and 281 Japanese-American men
(defined as Japanese men born and living in the U.S.) ages 40 to 49
years was conducted to assess intima-media thickness (IMT) of the
carotid artery, coronary artery calcification (CAC), and serum
fatty acids.

Results: Japanese men had the lowest levels of atherosclerosis,
whereas whites and Japanese Americans had similar levels. Japanese
had 2-fold higher levels of marine-derived n-3 fatty acids than
whites and Japanese Americans in the U.S. Japanese had significant
and nonsignificant inverse associations of marine-derived n-3 fatty
acids with IMT and CAC prevalence, respectively. The significant
inverse association with IMT remained after adjusting for
traditional cardiovascular risk factors. Neither whites nor
Japanese Americans had such associations. Significant differences
between Japanese and whites in multivariable-adjusted IMT (mean
difference 39 µm, 95% confidence interval [CI]: 21 to 57µm, p <
0.001) and CAC prevalence (mean difference 10.7%, 95% CI: 2.9% to
18.4%, p = 0.007) became nonsignificant after we adjusted further
for marine-derived n-3 fatty acids (22 µm, 95% CI: –1 to 46 µm, p =
0.065 and 5.0%, 95% CI: –5.3% to 15.4%, p = 0.341, respectively).

Conclusions: Very high levels of marine-derived n-3 fatty acids
have antiatherogenic properties that are independent of
traditional cardiovascular risk factors and may contribute to
lower the burden of atherosclerosis in Japanese, a lower burden
that is unlikely the result of genetic factors."

The Heart Scan Blog: ERA JUMP: Omega-3 fatty acids and plaque
<http://heartscanblog.blogspot.com/2008/07/era-jump-omega-3-fatty-acids-and-plaque.html>
<http://tinyurl.com/6cyw43>

Japanese diet rich in fish may hold secret to healthy heart
<http://www.eurekalert.org/pub_releases/2008-07/acoc-jdr072208.php>

Omega-3 rather than genetics is key to lack of CHD in Japanese?
<http://www.theheart.org/article/884341.do>

Omega-3 Rather Than Genetics Is Key to Lack of CHD in Japanese?
<http://www.medscape.com/viewarticle/578221>


--
Matti Narkia

http://ma.gnolia.com/groups/Nutrition
.

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