Re: [pyrnet] Size at one year/omega 6

["Tracy Bassett" <espinay@dynamite.com.au>]

<<I am not a trained nutritionist, so use your own judgment about my advice.
I am only repeating what I have read.  In people, corn oil is an omega 6
oil, (recently in 1990's) considered detrimental to health.  The omega 3 oil
from fish and omega 9 oil from olives are considered healthy essential fatty
acids.  Some nutritionists, say that the omega 6's can block the benefits of
the 3's and 9's.  Thus, the vet who recommended corn oil for the dogs diet
may be a little behind in nutrition as corn oil was thought to be great in
the 1970's and 1980's.>>Sandy White

Just catching up here as this one threw me for a loop and I had to go back
and check it out.  I hadn't heard that omega 6 was now considered
'detrimental to health' and didn't want to think I was behind the times in
my understanding (particularly when most people usually consider me to be
'way out there' LOL! ;-) ).  Same caveat here, I am not a trained
nutritionist, but at the risk of boring everybody..........

I think what you are perhaps referring to is the fact that omega 6s are
pro-inflammatory and that omega 3s are less inflammatory?  However, that's
very different from saying one is "good" and one is "bad".  Both are crucial
to proper functioning.

When trying to manipulate an out-of-whack immune system, such as might exist
with allergies, you can use the pro-inflammatory/less inflammatory fact to
your advantage -- increase the omega 3s and decrease the omega 6s.  BUT --
in a normal, healthy system, all the Essential Fatty Acids (EFAs) are vital
and work in concert with each other in a balancing act.

The most important omega 6 for dogs is linoleic acid.  Dogs can't make their
own, so it has to be in their diet.  The reason linoleic acid is so
important is that it helps allow electrolytes (minerals and fluids) to pass
across cell membranes.  So it helps prevent moisture loss from cells (which
helps prevent dry, flaky coats).  Omega 6s also are pro-inflammatory and
pro-aggregatory.  Compounds made in the cells from omega 6s cause
coagulation.  So, for instance, when you get a mosquito bite, the body's
cells defend themselves.  They rush blood to the site and cell compounds
made from omega 6s cause platelets to collect in order to stop the bleeding.
Those same omega 6 cell compounds also attract many white blood cells to the
site.  The combined result is the redness, swelling, pain and heat you feel.
Some inflammation is good, and a natural response. But sometimes the body
can get out of hand with its reactions (automimmune and allergic
conditions).  That's where omega 3 manipulation in the diet can come in.
(note: some people have started to describe omega 3s as anti-nflammatory.
They aren't, they are just LESS inflammatory.)

Omega 3 fatty acids also create the same cell compounds (eicosanoids) that
omega 6s produce, but the omega 3 eicosanoids are much less inflammatory and
some are also anti-aggregatory. So for dogs who have allergies, hot spots
and other inflammatory type disorders, higher levels of omega 3s can help
control (not prevent) the inflammation and itchiness seen in those
disorders. By influencing the ratio of omega 3 to omega 6 fatty acids in the
cell membrane, a blend of eicosanoids will be produced, with a reduction in
the symptoms of inflammation.

But, as always, it isn't quite as easy as just pushing the levels of omega 3
way up.  Because of the anti-aggregatory effects of the omega 3s (they
discourage the blood platelets from sticking together), it is possible to go
overboard with them. People in Greenland, who have a diet heavy in omega 3s
from deep-sea fish and marine mammals, also bleed longer than people
elsewhere. That's because the omega 3s don't help the platelets coagulate.

Omega 3s are a literal part of that "you are what you eat" saying.  If you
add omega 3 fatty acids to the diet, it shows up in the fat and the cell
membranes. Depending on how much omega 3 is circulating in the bloodstream,
it will show up in intestinal cells, for example, about two weeks from
feeding. It's thought that skin cells take 6 to 8 weeks to "pick up" the
omega 3s.

Corn oil has a 60 to 1 ratio of omega 6 to omega 3.  It is ususally
considered an omega 6 supplement as opposed to flax oil or fish (body) oil
which are primarily omega 3.  While there is still disagreement on the
'correct' (ie for a normal healthy system) omega 6 to omega 3 ratio, 5:1 is
probably a good mid-range number based on currently available research.
Because it is so hard to figure out exactly how much of each is in what you
are feeding, it gets very difficult to find a way to reach the ideal ratio
of the two EFAs anyway.  As with everything, it usually comes down to
approximates.  Nutrition after all, never has been, and probably never will
be an exact science :-).

Tracy Bassett
Canberra, Australia
espinay@dynamite.com.au
visit my webpage at http://members.dynamite.com.au/espinay/index.htm