MiFR: Flax, not Fish
mik...@my-deja.com
Further on the notion that taking our n3s as EPA/DHA may override our
genetic adaptation toward low mt membrane DHA (& thus low
peroxidizability):
Lipids 1997 May;32(5):497-506
Effect of docosahexaenoic acid on mouse mitochondrial membrane
properties.
Stillwell W, Jenski LJ, Crump FT, Ehringer W
Department of Biology, Indiana University-Purdue University at
Indianapolis
46202, USA.
... In this study, mitochondrial
docosahexaenoic acid (DHA) levels were increased by either dietary
manipulation
or by fusing the mitochondria with phospholipid vesicles made from
1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (18:0/22:6 PC).
...Mitochondria were isolated from young
(5-mon) and old (24-mon) mice which were maintained on either a diet
rich in
saturated fats (hydrogenated coconut oil) or rich in n-3 polyunsaturated
fats
(menhaden oil). Mitochondrial bioenergetic function was followed by RCI,
state 3
respiration, ATP level, and phosphate uptake. In addition, lipid
composition,
phospholipid area/molecule and extent of lipid peroxidation were also
determined. Decreases in RCI for the menhaden oil diet-modified
mitochondria
paralleled those in which DHA levels were enhanced by fusion with
phospholipid
vesicles. RCI reductions are attributed to DHA-induced increases in H+
movement,
producing diminished mitochondrial membrane potentials. ...
PMID: 9168456, UI: 97311741
3: Int J Vitam Nutr Res 1997;67(4):272-8
Rapid incorporation of docosahexaenoic acid from dietary sources into
brain
microsomal, synaptosomal and mitochondrial membranes in adult mice.
Suzuki H, Manabe S, Wada O, Crawford MA
National Food Research Institute, Tsukuba, Japan.
This study examined the incorporation of docosahexaenoic acid (DHA) from
several
dietary sources into the brain tissue and intracellular organelles in
mice which
had been fed a 5% palm oil (low n-3 fatty acid level) diet for 8 or 11
weeks.
The percentages of DHA in the tissues of mice fed 5% representative oils
for 30
days or 5% purified n-3 fatty acid diets for 6 days were analyzed using
gas
chromatography. The percentage of DHA in the brain was ranked in the
following
order: the salmon oil diet group > the sardine oil diet group > > the
perilla
oil diet group > > the lard and palm oil diet groups for the 30 day
feeding
trial; and the DHA diet group > > the eicosapentaenoic acid and
alpha-linolenic
acid diet groups for the 6 day feeding trial. The percentage of
arachidonic acid
showed a more dramatic decrease than that of docosapentaenoic acid. ....
The majority of the DHA
incorporated into the brain was recovered in microsomal, synaptosomal,
and
mitochondrial fractions separated by density gradient centrifugation.
These
membrane fractions took up DHA within several days. These results
suggest that
the intake of DHA itself increases the DHA level of brain membranes more
rapidly
than intake of the precursors in animals fed a low n-3 fatty acid level
diet.
PMID: 9285258, UI: 97431165
And, worst of all:
Ann Nutr Metab 1989;33(3):125-42
Changes in phospholipid fatty acid composition of mouse cardiac
organelles after
feeding graded amounts of docosahexaenoate in presence of high levels of
linoleate. Effect on cardiac ATPase activities.
Croset M, Kinsella JE
Lipid Research Laboratory, Cornell University, Ithaca, N.Y.
Mice were fed diets containing a constant supply of linoleic acid
(18:2n-6, LA)
as ethyl ester representing 5% by weight of the total fat (5 wt%), in
combination with graded amounts of purified docosahexaenoate (22:6n-3,
DHA).
Cardiac sarcoplasmic reticulum (SR) and mitochondrial phospholipids (PL)
from
mice fed the diet without DHA contained higher levels of n-6 long chain
polyunsaturated fatty acids (PUFA) (22:4n-6 and 22:5n-6) compared to
total PL of
liver. In the cardiac mitochondrial PL, the level of LA, DHA, the total
content
of PUFA and the P/S ratio were significantly higher than in SR. A small
increase
in dietary DHA from 0 to 0.43 wt% induced a 3.6-fold increase in PL DHA
content
from both cardiac organelles, with a concurrent reduction of n-6 PUFA.
The
changes in fatty acid PL composition were much more moderate when
dietary DHA
level was increased to 0.85 and 3.74 wt%. Feeding the lowest amount of
DHA
resulted in a 6-fold decrease in the value of n-6/n-3 PUFA ratio and a
3.5-fold
decrease in the value of 20 carbon chain/22 carbon chain PUFA ratio. DHA
was
readily depleted from cardiac PL, and only arachidonic acid was retained
in the
PL from both organelles, after feeding a fat-deficient diet. Despite
these
drastic modifications in PL fatty acid composition, the maximum velocity
(Vm) of
SR Ca2+, Mg2+-ATPase was not affected, which indicates that SR cardiac
membrane
adapts to changes in fatty acid composition to prevent important
modifications
of its functional properties. However, the Vm of mitochondrial
oligomycin-sensitive ATPase was slightly increased in mice fed the
lowest amount
of DHA. This might be due to an increase in P/S ratio and/or to a
modification
of cardiolipin fatty acid composition, since this PL is required for
optimum
function of this enzyme. It is concluded that DHA is strongly taken up
by mouse
cardiac PL, even in the presence of high dietary LA levels, but its
acylation
into PL has only little effect on the cardiac ATPase activities.
PMID: 2529810, UI: 90024920
The alarm bells are somewhat muted by this, however:
Biosci Biotechnol Biochem 1998 Sep;62(9):1698-706
Dietary docosahexaenoic acid dose not promote lipid peroxidation in rat
tissue
to the extent expected from peroxidizability index of the lipids.
Kubo K, Saito M, Tadokoro T, Maekawa A
Division of Food Science, National Institute of Health and Nutrition,
Tokyo,
Japan.
Docosahexaenoic acid (DHA) ingestion enhanced the susceptibility of rat
liver
and kidney to lipid peroxidation as a function of the dietary DHA level,
but did
not increase lipid peroxides as assessed by thiobarbituric acid (TBA)
values to
the level expected from the peroxidizability index of the tissue total
lipids.
This phenomenon was especially prominent in the liver. In the liver, the
higher
proportion of DHA in the non-phosphorus lipids might play an important
role in
lessening the susceptibility of the tissue to lipid peroxidation. In the
brain
and testis, on the other hand, lipid peroxide levels were decreased when
DHA was
given to the animals. In the testis, in particular, the proportion of
DHA in
total lipids was lowest among all tissues examined, even when a
relatively high
level of DHA had been ingested, and this could be related to the low
lipid
peroxide level. Therefore, the protection against lipid peroxidation
differed
from tissue to tissue, even from the viewpoint of the fatty acid
composition of
the tissue lipids. In addition, changes in the lipid peroxide levels of
the
liver, kidney, brain and testis, as assessed by TBA values, seemed to be
associated with changes in the peroxidizability index of
phosphatidylcholine
(+cardiolipin) in each tissue.
PMID: 9805370, UI: 99022186
-Michael
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