Fatty Acid Peroxidation & Free Radicals
Double bonds are formed in fatty acids when two adjacent carbon atoms each have one hydrogen atom taken away. The process is called desaturation. The double bond can be in two forms. Cis with both missing hydrogen atoms on the same side or trans when the two missing hydrogen atoms are on opposite sides.
Here is a graphic for the 18 chain saturated
fatty acid Stearic (18:0):
Cis Double Bond fatty acids
Notice now the Oleic (diagram below) is missing
2 hydrogen atoms on the bottom side at the
9th & 10th carbon atom from the left
end. That it starts on the 9th carbon atom
is what makes it a Omega 9 family fatty acid.
The unbalanced (top verus botom) repulsive
forces created between hydrogen atom to hydrogen
atom forces the double bond to bend in the
direction of less repulsive forces and it
is this bent and open double bond which causes
Oleic (18:1w9) to be more susceptible to
free radical attack than the saturated form.
It also alters it's chemical properties and
makes it a more valuable and biochemically
active fatty acid than the saturated form
18:0.
Like Omega 3 LNA, EPA, DHA and Omega 6 LA,
we do need some of these double bond rich
fatty acids in our diet, just not too much.
Here is the 18 chain monounsaturated single
double bond cis fat Oleic (18:1w9):
Trans double bond fatty acids
Note in the graphic below, the double bond
in the trans faty acid starting at the 9th
carbon atom from the left end has the hydrogen
atom on the 10th carbon on the bottom instead
of the top, as in the normal cis form above.
Normally trans fatty acids are not health
friendly and are formed when fatty acids
with cis double bonds are heated. Note also
that this trans configuration results in
the fatty acid not bending as the repulsive
forces have been made equal top and bottom.
This non bendable trans double bond fatty
acid form is why you should avoid any RBD (Refined, Bleached and Deodorized) oils
or fats as the processing tends to alter
the normal & healthy cis double bonds
into unhealthy and straight trans double
bond fatty acids.
Here is the unhealthy 18 chain monounsaturated
single double bond trans fatty acid Oleic
(18:1w9 trans)
Hydrogenation is another process which alters normal cis
double bonds by elimination them entirely
(filling in the missing hydrogen atoms) in
an effort to reduce the peroxidation / rancidity
/ spoilage rate of the oil / fat. This is
achieved but at a cost of the loss of the
unique biochemical effects of the double
bonds. Hydrogenation is how margarines are
made from cheap RBD veggie oils by removing
all the double bonds (filling them in with
the missing hydrogen atoms) and thus the
resultant saturated fatty acids can pack
together tightly and be made to physically
resemble butter. Not my cup of tea!
Peroxidation is the dark side of double bond fatty acids
as their carbon atom to carbon atom double
bonds are much more easily attacked by free
radicals than the more normal and common
carbon to carbon single bonds.
It is estimated the first double bond in
a fatty acid is 50 x more susceptible to
free radical damage than zero bond saturated
fat and for the second and following double
bonds the susceptibility to free radical
damage goes up another 40 x per bond.
Intake of foods and/or supplements with antioxidant
vitamins and its impact on CHD
"The tendency of unsaturated lipids
to undergo oxidation is related to the number
of double bonds in the fatty acid molecule.
Each additional double bond after the initial
double bond found in monounsaturated fatty
acids increases susceptibility to peroxidation
by forty fold while a fatty acid with one
double bond is about fifty times more susceptible
to peroxidation than a saturated fatty acid.
Hence, a fatty acid with three double bonds
is oxidized eighty times as readily as a
fatty acid with only one double bond. This
oxidative susceptibility of fatty acid is
reflected by the tendency of various oils
to oxidize. "
From this we can construct a table of the
various fatty acids and their sensitivity
to peroxidation assuming saturated is 1.
1) Zero bond saturated = 1
2) One bond Omega 9 OA (monounsaturated)
= 50
3) Two bond Omega 6 LA (polyunsaturated)
= 90
4) Three bond Omega 3 LNA (polyunsaturated)
= 130
5) Four bond Omega 6 AA (polyunsaturated)
= 170
6) Five bond Omega 3 EPA (polyunsaturated)
= 210
7) Six bond Omega 3 DHA (polyunsaturated)
= 250
So polyunsaturated Omega 6 LA (18:2w6) is
90 times more susceptible than sat fats due
to its 2 double bonds (50+40):
And polyunsaturated Omega 3 LNA (18:3w3)
is 130 times more susceptible than sat fat
due to it's three bonds (50+40+40):
It is these double bonds which give these
fatty acid molecules their unique properties
and also elevated free radical damage susceptibility.
We only need about 2 - 3 g of Omega 6 LA
and 2 - 3 g of Omega 3 LNA. Anymore can be
damaging and excessive Omega 6 LA is very
bad (body wide) and should be aggressively
eliminated from the diet as veggies will
provide ALL the Omega 6 LA anyone needs.
A recent US expert working committee recommends
the following:
Polyunsaturated fatty acids in the food chain
in the United States
Omega 6 LA < 6.7 g (this is the hard bit
as Omega 6 LA is everywhere)
Omega 3 LNA ~ 2.2 g (1 tablespoon of ground
organic flax)
Omega 3 EPA+DHA ~ 0.65 g (1 - 2 serves a
week of salmon, tuna, mackerel,herring, sardines
or 2 fish oil capsules a day)
This is ALL the Omega 3 and Omega 6 you need
for Optimal Health.
Now that you have a basic understanding of
fatty acids, imagine what happens if you
hydrogenate a double bond fatty acid by forcing
hydrogen atoms into all the places in the
double bonds that are lacking them. The result
is a once beneficial fatty acid now made
into a totally saturated form, if totally
successful or full of half way conversion
horrors (trans fats, double bond position
shifts, etc) if not.
Click for a graphic of the fatty acid analysis
of various oils, fats and fat rich food:
OilAnalysis.gif
and here is a Interactive Excel spreadsheet
which will allow you to input your daily
intakes and have your relative peroxidation
risk calculated:
OilAnalysis.xls (Requires Microsoft Excel)
The bottom line is that small amounts of
Omega 3 and Omega 6 are very beneficial to
your health and reduced CVD risk. Just realize
you may open pandora's box if you over do
the powerful Omega 3 & 6 fatty acids.
Never in our Paleo past, did we ever consumed
more than small amounts of these fatty acids
and neither should you.
This means giving up the veggie oils and
margarines as these are very un-natural foods.
I eat about 25 g a day of Virgin Coconut
Oil (VCNO), 15 g of ground flax (1 tablespoon),
5 g of Extra Virgin Olive Oil (EVOO) and
2 g of fish oil (normally from fish but sometimes
from fish oil capsules). You do not need more. The VCNO is used for cooking,
baking, morning smoothies and the EVOO is
mixed 45 - 45 with the VCNO and some ground
flax for salads.
Optimal Health, Happiness & Long Life,
Greg Watson
