Importance of Omega Three Fats in
Health and Disease
By Dr.
William Connor
Interest in omega-3 fatty
acids began some 30 years ago and there are now several thousand papers
in the scientific literature supporting their benefits.
There is little doubt that
omega-3 fatty acids are important in human nutrition. They are
significant structural components of the cell membranes of tissues
throughout the body and are especially rich in the retina, brain, and
sperm, in which docosahexaenoic acid (DHA) constitutes 36.4% of total
fatty acids
Membrane fluidity is
essential for proper functioning of these tissues. In the retina, where
omega-3 fatty acids are especially important, deficiency can result in
decreased vision and abnormal electroretinogram results.
Omega-3 Fatty acids are essential fatty acids, necessary from
conception through pregnancy and infancy and, undoubtedly, throughout
life.
The ratio of omega-6 to
omega-3 fatty acids has increased in industrialized societies because of
increased consumption of vegetable oils rich in omega-6 fatty acids, ie,
linoleic acid, and reduced consumption of foods rich in omega-3 fatty
acids.
Another important feature
of omega-3 fatty acids is their role in the prevention and modulation of
certain diseases that are common in Western civilization.
The following is a partial
list of diseases that may be prevented or ameliorated with omega-3 fatty
acids, in descending order of the strength of the available evidence as
perceived by this reviewer:
- Coronary heart disease
and stroke;
- Essential fatty acid
deficiency in infancy (retinal and brain development);
- Autoimmune disorders
(e.g., lupus and nephropathy);
- Crohn disease;
- Cancers of the breast,
colon, and prostate;
- Mild hypertension; and
- Rheumatoid arthritis.
Cardiovascular Benefits Of Omega-3 Fatty Acids
The strongest evidence of a
relation between omega-3 fatty acids and disease is the inverse relation
between the amount of omega-3 fatty acids in the diet and in blood and
tissues and the occurrence of coronary heart disease and its many
complications.
Effects of omega-3 fatty
acids on coronary heart disease have been shown in hundreds of
experiments in animals, humans, tissue culture studies, and clinical
trials.
Omega-3 fatty acids from
fish have been shown to be protective of heart disease and, by a variety
of mechanisms, prevent deaths from coronary disease, particularly
cardiac arrest.
The unique properties of
these fatty acids in coronary heart disease first became apparent in the
investigations of the health status of Greenland Eskimos who consumed
diets very high in fat from seals, whales, and fish and yet had a low
rate of coronary heart disease.
Further studies clarified
this paradox. The fat the Eskimos consumed contained large quantities of
the very-long-chain and highly polyunsaturated fatty acids of EPA and
DHA, which are abundant in fish, shellfish, and sea mammals and are
scarce or absent in land animals and plants. EPA and DHA are synthesized
by phytoplankton, which are the plants of the waters and the base of the
food chain for marine life.
Dietary omega-3 fatty acids
act to prevent heart disease through a variety of actions. They:
- Prevent arrhythmias
(ventricular tachycardia and fibrillation),
- Prostaglandin and
leukotriene precursors,
- Have anti-inflammatory
properties,
- Inhibit synthesis of
cytokines and mitogens,
- Stimulate
endothelial-derived nitric oxide,
- Antithrombotic,
- Have hypolipidemic
properties with effects on triglycerides and VLDLs, and
- Inhibit atherosclerosis.
EPA and DHA have strong
antiarrhythmic action on the heart. In experimental animals and tissue
culture systems, EPA and DHA prevent the development of ventricular
tachycardia and fibrillation.
Even total mortality has
been improved in several studies in which the omega-3 fatty acid intake
was increased. In one study, men who consumed salmon 1 time/wk had a 70%
less likelihood of cardiac arrest.
In another study overall
mortality was decreased by 29% in men with overt cardiovascular disease
who consumed omega-3 fatty acids from fish or fish oil, probably because
of the reduction in cardiac arrests.
The most recent data on
fish consumption and risk of sudden cardiac death were from the
Physician's Health Study in the United States in 20551 male physicians.
Consumption of 1 fish meal/week was associated with a 52% lower risk of
sudden cardiac death compared with consumption of <1 fish meal/month.
Total Death Rate Was Also Lower In Those Who Ate Fish.
Thrombosis, or the tendency
to form blood clots, is a major complication of coronary atherosclerosis
that can lead to heart attacks.
The omega-3 fatty acids
from fish oil have powerful antithrombotic actions. EPA inhibits the
synthesis of thromboxane A2 from arachidonic acid in platelets. This
prostaglandin causes platelet aggregation and vasoconstriction.
As a result, fish oil
ingestion by humans increases the bleeding time and decreases the
stickiness of the platelets for aggregation to glass beads. In addition,
the administration of fish oil enhances the production of prostacyclin,
a prostaglandin that produces vasodilation and less sticky platelets.
Reduced Atherosclerosis
The EPA and DHA contained
in fish oil fed to experimental animals actually inhibited development
of atherosclerosis. There is evidence in both pigs and monkeys that
dietary fish oil prevents atherosclerosis by actions other than reducing
plasma cholesterol concentrations.
Atherosclerotic plaque
formation may also be lessened by the reduction in growth factors after
fish-oil consumption. Not only is platelet-derived growth factor
diminished by fish oil consumption, but its messenger RNA is reduced.
Because atherosclerosis begins with cellular proliferation in response
to the influx of cholesterol-rich lipoproteins, the inhibition of this
proliferation would greatly reduce the growth of the atherosclerotic
plaque.
Reduced Cholesterol Levels
The pronounced effect of
fish oil on high blood fats or elevated cholesterol levels is especially
well documented and is supported by results of precise dietary studies
in which the effects of a diet rich in salmon oil were compared with
those of a vegetable oil and a diet high in saturated fat.
Fish oil in particular was
shown to lower plasma cholesterol and triglyceride concentrations.
Apolipoprotein B production is reduced by consumption of fish oil in
comparison with vegetable oils such as safflower or olive oil.
Omega-3 Fatty Acids Essential Components Of Cell Membranes In Infancy
There are 2 critical
periods for the acquisition of these essential omega-3 fatty acids:
during fetal development and after birth until the biochemical
development in the brain and retina is completed.
As already noted, the
omega-3 fatty acid DHA is an important constituent of the cell membrane
of these neural structures.
Omega-3 fatty acid
deficiency is manifested in both the blood and in tissue biochemistry.
Of note is a strikingly low concentration of DHA, which may fall to as
much as one-fifth of the normal amount.
In addition, the body
attempts to replace the deficient DHA with another highly
polyunsaturated fatty acid of the omega-6 series. In rhesus monkeys,
omega-3 fatty acid -- deficient diets fed to pregnant animals and then
continued after birth induce profound functional changes such as reduced
vision, abnormal electroretinograms, impaired visual evoked potential,
more stereotypic behavior (e.g., pacing), and, perhaps, disturbances of
cognition.
Some of these findings have
been replicated in infants fed formulas deficient in omega-3 fatty
acids. Most studies of premature infants have shown visual impairment
and abnormal electroretinograms.
A recent study in full-term
infants, in which a standard infant formula was compared with human milk
and with formulas enriched with DHA, provided unequivocal evidence of
considerable differences in visual evoked potential.
In all of the human
studies, the biochemical evidence in plasma, red blood cells, and,
occasionally, in tissues from autopsied infants has substantiated the
omega-3 fatty acid deficiency state. The lower concentrations of DHA in
plasma and erythrocytes are mirrored by lower concentrations in the
brain and retina. Formula-fed infants have lower concentrations of brain
DHA than do infants fed human milk. They also have lower intelligence
quotients.
During pregnancy, both
maternal stores and dietary intake of omega-3 fatty acids are of
importance in insuring that the baby has adequate amounts of omega-3
fatty acids at the time of birth.
All the polyunsaturated
fatty acids, including DHA, are transferred across the placenta into
fetal blood. In addition, EPA and DHA in maternal adipose tissue can be
mobilized as free fatty acids bound to albumin and be made available to
the developing fetus via placenta transport.
Several studies in monkeys
have indicated that when the maternal diet is deficient in omega-3 fatty
acids, the infant at birth is likewise deficient as evidenced by low DHA
concentrations in their plasma and red blood cells.
In humans, it was shown
that the administration of fish oil or sardines to pregnant women led to
higher DHA concentrations in both maternal plasma and red blood cells
and in cord blood plasma and red blood cells at the time of birth.
Once membrane phospholipids
have adequate concentrations of DHA, there is an avid retention of these
fatty acids in the brain and the retina, even though the diet may
subsequently be deficient. Several studies illustrate clearly the
effects of omega-3 deficiency in both animals and humans.
American Journal of Clinical Nutrition, Vol. 71, No. 1, 171S-175S,
January 2000
DR. MERCOLA'S COMMENT:
Omega three fats are
essential to your health. You can certainly get them from cod liver oil
or fish oil.
If you already have
significant sun exposure then you should not take cod liver oil as you
will run the risk of overdosing on vitamin D.
You should then take
fish oil capsules. The standard fish oil capsule is 180 mg of EPA and
120 mg of DHA. You should take approximately one capsule for every ten
pounds of body weight, preferably in two divided doses.
So if you weigh 160
pounds you would take 8 capsules twice a day. If you have problems with
belching them up, you will want to consider taking them on an empty
stomach.
Probably the best value
for fish oil capsules is the one we sell in our office. The Kirkland
brand from Costco. They sell a 300 capsule bottle for about $7.50.
Because Costco has such a high turnover, the oil is very fresh. You can
tell, by puncturing one of the capsules and seeing if there is any
"fishy" aftertaste. This is usually a sign of rancid fat and an
indication of an inferior product.
Cod liver oil has the
benefit of providing you with vitamin D and A. A reasonable dose for cod
liver oil is one teaspoon for every 30-40 pounds of body weight. If you
use cod liver oil during your summer you will need to be careful of
vitamin D toxicity and I suggest you review the information on
vitamin D testing.
When you take fish oil
supplements or cod liver oil in the doses I recommend please be sure and
take a one vitamin E 400 unit supplement per day as this will help serve
to protect the fat from oxidation. This is less of an issue with the cod
liver oil as the vitamin D itself is a very potent anti-oxidant.
You will also need extra
amounts of the "fourth and unforgotten" oil soluble vitamin, vitamin K.
If you are juicing plenty of green vegetables and taking the cod liver
oil or fish oil with the juice you should absorb the vitamin K in the
vegetable juice. However, if you have osteoporosis or osteopenia, you
will want to consider adding an extra 1000 mcg ( 1 mg ) of vitamin K per
day.
Generally our diet
contains far to much omega 6 fats. Experts looking at the dietary ratio
of omega-6 to omega-3 fatty acids suggest that in early human history
the ratio was about 1:1. Currently most Americans eat a dietary ratio
that falls between 20:1 and 50:1. The optimal ratio is most likely
closer to the original ratio of 1:1. For most of us this means greatly
reducing the omega-6 fatty acids we consume and increasing the amount of
omega-3 fatty acids.
Please recognize that we get ALL the omega-6 and omega-9 fat we need
from food. We do NOT need to take any supplements for these fats. Many
of the omega fat supplements you see in health food stores will only
serve to worsen your health, not improve it as they contain omega 6 fats
which will worsen your omega-6 to omega-3 ratio.
I strongly recommend avoiding sunflower, corn, soy, safflower, canola,
or products that contain these oils. That is no hydrogenated or
partially hydrogenated fats, no margarine, no vegetable oil, no
shortening. These oils are chock full of omega-6 fats and will only
worsen your omega 6:omega 3 ratio.
Acceptable oils will be a high quality extra virgin olive oil,
coconut oil,
avocados, and organic butter, or better yet grass-fed organic butter.
Another way to improve your omega 6:3 ratio is to change the type of
meat you are eating. You could consume more game meat like venison, or
other game animals that are raised exclusively on grass type foods.
However, these are hard to find and generally more expensive than beef.
Since nearly all cattle
are grain fed before slaughter, if you eat most traditionally raised
beef, it will typically worsen you omega 6:omega 3 ratio.
Normally a good ratio for omega 6:3 in fish is 2 or 3 to 1. The lower
the better. Grassfed beef from Grassfed Organics is much higher in Omega
3 than fish, with a 6:3 ratio of 0.16 to
1. This information is from a study done at Iowa State University
in August 2001.
To get the necessary Omega-3 fatty acids, you should consider eating
meat that is allowed to "free-range", or in the case of cattle, to be
grass-fed. Unfortunately, you cannot buy this grass-fed beef at your
local grocery store.
You must also be careful as many stores will advertise grass-fed beef
but it really isn't. They do this as ALL cattle are grass fed, but the
key is what they are fed the months prior to being processed.
Most all cattle are shipped to giant feed lots and fed corn to fatten
them up. You will need to call the person who actually grew the beef,
NOT the store manager, to find out the truth.
The least expensive way to obtain authentic grass fed beef would be to
find a farmer who is growing the beef who you can trust and buy a half a
side of beef from him. This way you save the shipping and also receive a
reduced rate on the meat.
An inexpensive, yet
effective way to determine if the meat is really from a grass fed animal
is to purchase the ground beef. Slowly cook the beef till done and drain
and collect all the fat. Grass fed beef is very high in omega-3 fats and
will be relatively thin compared to traditionally prepared ground beef.
It will also be a liquid at room temperature as it has very few
saturated fats which are mostly solid at room temperature.
However, most of us live in large urban areas and do not have the time
for this process. Just as it would be ideal to have an organic garden
and grow your own vegetables, most of us elect not to do that for time
or space reasons.
I used to have an organic garden, but my schedule just would not allow
me to have that luxury anymore. So, if you are convinced, like I am,
that grass-fed beef is better for you and you would like the convenience
of being able to order it over the Net, you can buy grass-fed beef
online, shipped overnight to your door, at
Grassfed Organics.
Another popular source
of omega-3 fats are from fish but they should be consumed with caution
as they have been linked to
high levels of
mercury. Even the conservative FDA advises all pregnant women to
avoid fish during pregnancy as 60,000 children suffer brain injury every
year in the US from their moms eating mercury contaminated fish. The
safest fish are Summer, Flounder, Wild Pacific Salmon, Croaker,
Sardines, Haddock and Tilapia.
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