Flax is Not the Best Omega-3 Fat By Dr. Artemis P. Simopoulos

[Guest guest]

http://www.mercola.com/2002/apr/3/evolution.htm

 

Over the past 20 years many studies and clinical investigations have

been carried out on the metabolism of polyunsaturated fats in general

and on omega-3 fats in particular.

 

Today we know that omega-3 fats are essential for normal growth and

development and may play an important role in the prevention and

treatment of coronary artery disease, hypertension, diabetes,

arthritis, other inflammatory and autoimmune disorders, and cancer

(1-7).

 

Research has been done in animal models, tissue cultures, and human

beings. The original observational studies have given way to

controlled clinical trials. Great progress has taken place in our

knowledge of the physiologic and molecular mechanisms of the various

fats in health and disease. Specifically, their beneficial effects

have been shown in the prevention and management of:

 

* Coronary heart disease (8, 9),

* Hypertension (10-12)

* Type 2 diabetes (13, 14)

* Renal disease (15, 16)

* Rheumatoid arthritis (17)

* Ulcerative colitis (18)

* Crohn disease (19)

* Chronic obstructive pulmonary disease (20)

 

However, this review focuses on the evolutionary aspects of diet, the

biological effects of omega-6 and omega-3 fats, and the effects of

dietary -linolenic acid (ALA) compared with long-chain omega-3

derivatives on coronary heart disease and diabetes.

 

Essential Fats Such As Omega-6 And Omega-3 Have Been Part Of Our Diet

Since The Beginning Of Human Life

 

Before the agricultural revolution 10,000 years ago humans consumed

about equal amounts of both. Over the past 150 years this balance has

been upset. Current estimates in Western cultures suggest a ratio of

omega-6 to omega-3 fats of 10-20:1 instead of 1-4:1.

 

On the basis of estimates from studies in Paleolithic nutrition and

modern-day hunter-gatherer populations, it appears that human beings

evolved consuming a diet that was much lower in saturated fats than is

today's diet (21).

 

Furthermore, the diet contained small and roughly equal amounts of

omega-6 and omega-3 PUFAs (ratio of 1-2:1) and much lower amounts of

trans fats than does today's diet (21, 22). The current Western diet

is very high in omega-6 fats (the ratio of omega-6 to omega-3 fats is

20-30:1) because of the indiscriminate recommendation to substitute

omega-6 fats for saturated fats to lower serum cholesterol

concentrations (23).

 

Intake of omega-3 fats is much lower today because of the decrease in

fish consumption and the industrial production of animal feeds rich in

grains containing omega-3 fats, leading to production of meat rich in

omega-6 and poor in omega-3 fats (24). The same is true for cultured

fish (25) and eggs (26).

 

Even cultivated vegetables contain fewer omega-3 fats than do plants

in the wild (27, 28). In summary, modern agriculture, with its

emphasis on production, has decreased the omega-3 fat content in many

foods: green leafy vegetables, animal meats, eggs, and even fish.

 

Biological Effects of Omega-6 and Omega-3 Fats

 

Linoleic acid and alpha linolenic acid ALA and their long-chain

derivatives are important components of animal and plant cell

membranes. When you eat fish or fish oil, the EPA and DHA partially

replace the omega-6 fats especially arachidonic acid in cell

membranes.

 

As a result eating EPA and DHA from fish or fish oil leads to:

 

1) Decreased concentrations of thromboxane A2, a potent platelet

aggregator and vasoconstrictor;

 

2) Decreased formation of leukotriene B4, an inducer of

inflammation and a powerful inducer of leukocyte chemotaxis and

adherence;

 

3) Increased concentrations of thromboxane A3, a weak platelet

aggregator and vasoconstrictor;

 

4) Increased concentrations of prostacyclin PGI3, leading to an

overall increase in total prostacyclin by increasing PGI3 without

decreasing PGI2 (both PGI2 and PGI3 are active vasodilators and

inhibitors of platelet aggregation); and

 

6) Increased concentrations of leukotriene B5, a weak inducer of

inflammation and chemotactic agent (29, 30).

 

Because of the increased amounts of omega-6 fats in the Western diet,

the eicosanoid metabolic products from arachadonic acid, specifically

prostaglandins, thromboxanes, leukotrienes, hydroxy fats, and

lipoxins, are formed in larger quantities than those formed from

omega-3 fats, specifically EPA.

 

A diet rich in omega-6 fats shifts the physiologic state to one that

is prothrombotic and proaggregatory, with increases in blood

viscosity, vasospasm, and vasoconstriction and decreases in bleeding

time.

 

The higher the ratio of omega-6 to omega-3 fats the higher is the

death rate from cardiovascular disease (33). As the ratio of omega-6

to omega-3 increases, the prevalence of type 2 diabetes also increases

(13).

 

Effects of Dietary Flax Compared With Fish Oil

 

ALA, found in flax seed is the precursor of omega-3 fats, can be

converted to long-chain omega-3 fats and can therefore be substituted

for fish oils.

 

However, ALA is not equivalent in its biological effects to the

long-chain omega-3 fats found in marine oils. EPA and DHA are more

rapidly incorporated into plasma and membrane lipids and produce more

rapid effects than does ALA.

 

Experimental studies suggest that intake of 3-4 grams of ALA per day

is equivalent to 0.3 grams (300 mg) EPA per day.

 

Relatively large reserves of LA in body fat, as are found in vegans or

in the diet of omnivores in Western societies, would tend to slow down

the formation of long-chain omega-3 fats like EPA and DHA from ALA.

 

One advantage of the consumption of ALA over omega-3 fats from fish is

that the problem of insufficient vitamin E intake does not exist with

high intake of ALA from plant sources.

 

Benefits of Omega-3 Fats

 

Dietary intake of omega-3 fats from seafood was associated with

reduced risk of primary cardiac arrest compared with no fish intake;

5.5 g omega-3 fats per month or the equivalent of 1 fatty fish meal

per week was associated with a 50% reduction in the risk of primary

cardiac arrest.

 

A 5.0% increase in omega-3 fats was associated with a 70% reduction in

the risk of primary cardiac arrest.

 

An increase in EPA and DHA also leads to increases in membrane

fluidity, the number of insulin receptors, and insulin action.

 

Clinical interventions provide further support for the beneficial

effects of omega-3 fats in the prevention and management of

cardiovascular disease, hyperinsulinemia, and possibly type 2

diabetes.

 

Omega-3 fats affect coronary heart disease beneficially not by

changing serum lipid concentrations, although EPA and DHA do lower

triglycerides, by reducing blood clotting in vessel walls (72, 76) and

ventricular arrhythmias (8, 9, 75, 77).

 

Am. J. Clinical Nutrition, September 1999; 70: 560 - 569

 

References

 

Dr. Mercola's Comment:

 

Always remember omega-3 fats are essential to your, and your

children's, health. The best source for omega-3 is fish oil and cod

liver oil, as, unlike other sources such as walnuts or flax seeds, it

is high in two fatty acids crucial to human health, DHA and EPA. These

two fatty acids are pivotal in preventing heart disease, cancer, and

many other diseases. The human brain is also highly dependent on DHA -

low DHA levels have been linked to depression, schizophrenia, memory

loss, and a higher risk of developing Alzheimer's.

 

When choosing your fish oil or cod liver oil, it is important to

remember that not all brands are the same. In my research -- and in my

clinical experience with my patients -- I have found that 1) the

liquid form is superior to capsules; 2) that certain brands definitely

seem inferior to others; 3) that the Carlson's brand of fish oil/cod

liver oil is of an exceptional quality and purity. It is likely not

the only brand in the world of such high quality, but up to this point

it is the only one of such quality that I can recommend, so I now

offer the Carlson's fish oil and cod liver oil on Mercola.com; you can

also check your local health food store to see if they carry it.

 

As for fish itself, patients consuming nearly every type of fish these

days are showing high levels of mercury in their systems. In short --

and sadly, as it would otherwise be one of the healthiest meats on the

planet -- I now advise against consuming any fish from any source,

including fresh water, farm-raised or ocean, because most are

contaminated with mercury. If you do consume fish, you should be

certain the provider can demonstrate that the fish are free of

detectable levels of mercury and other toxins (Carlson's fish oil/cod

liver oil has been entirely purified so you don't have to worry about

these toxins.)

 

So what is the difference between fish oil and cod liver oil? In

short, fish oil should be consumed in warm weather months and warm

climates, while cod liver oil should be consumed in cool weather

months and cool climates. Cod liver oil is high in vitamin D (and

vitamin A); those in cool weather climates do not generally get enough

vitamin D. However, in warm weather, their vitamin D is usually

sufficient, as sunshine is one of the primary methods of obtaining

this vitamin; if you consume too much vitamin D in these warm weather

months, you do risk overdosing.

 

A reasonable dose for both fish oil and cod liver oil is one teaspoon

for every 50 pounds of body weight daily.

 

Generally, our diets contain not only far too little omega-3, but far

too many 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 not only increasing

our omega-3 intake through fish oil, but also greatly reducing the

omega-6 fatty acids we consume.

 

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 that will only worsen your omega-6 to omega-3 ratio.

 

I strongly recommend avoiding sunflower, corn, soy, safflower, and

canola oil, and products that contain these oils. This also means no

hydrogenated or partially hydrogenated fats, no margarine, no

vegetable oil and no shortening. These oils are full of omega-6 fats

and will only worsen your omega-6 to omega-3 ratio.

 

Acceptable oils include 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. Since I can't recommend fish due to their high

levels of mercury and other toxins these days, the best meats are

those raised primarily or entirely on grass diets. Nearly all cattle

found in grocery stores and restaurants are grain-fed before

slaughter, so if you eat this type of beef, it will typically worsen

you omega 6:omega 3 ratio. Though it may sound unusual to some, two of

the best meats on the planet -- in terms of nutrition value and their

incredible taste -- are bison and ostrich. And on Mercola.com, I offer

bison meat and our exclusive omega-3-rich ostrich meat, both of which

are free-ranged, fed primarily grass/alfalfa diets, and contain no

antibiotics or steroids. Whether from my site or elsewhere, I urge you

to try bison and ostrich.

 

You can also consume a more " gamey " meat like venison, or try

grass-fed beef, which I also highly recommend on Mercola.com. The

grass-fed beef I recommend is even 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). It is still hard to find in grocery

stores, however, and unlike bison and ostrich -- which both taste like

prime beef -- some find the taste of grass-fed beef too lean.

 

On a side-note, you should be cautious of stores advertising grass-fed

beef that really isn't true grass-fed. ALL cattle are grass-fed to

some small extent, 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. Your best bet is to call the person who

actually grew the beef, NOT the store manager, to find out the truth.

Another effective way to determine if the meat is really from a

grass-fed animal is to purchase the ground beef and slowly cook it

until it's done, then drain and collect all the fat. Grass-fed beef

will contain a relatively small amount of such fat compared to

traditionally prepared ground beef (which is why some find the taste

of grass-fed too lean!)

 

In summary:

 

1) Most Americans, young and old, are highly deficient in omega-3,

and one of the best things you can do for yourself and your children

is routinely consume fish oil in warm months and cod liver oil in cool

months, as they are high in the best kind of omega-3.

 

2) You should cut out or reduce the oils and foods high in omega-6

fats, as Americans get far too much of them. This includes corn,

sunflower, soy, canola and safflower oil, margarine, vegetable oil and

shortening.

 

3) You should eat healthy meats, as store-bought beef and other

common meats can worsen your omega-6 to omega-3 ratio. Bison and

ostrich are two great-tasting and very healthy choices, and game

animals or beef that is truly grass-fed are other good options.