Essential
Fats
www.essentialfats.com |
Fatty acids (the key components of fat) are classified into
two major groups: those that the body can easily make, called Non-Essential Fatty
Acids, and those that the body cannot make, called Essential Fatty Acids (EFAs).
Since the body cannot make EFAs, we must consume them as part
of our diets. This is not true of other types of fat, because the body can
easily convert carbohydrates and protein to saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), but not to polyunsaturated
fatty acids (PUFAs).
In this way, essential fats are similar to vitamins, which we
cannot manufacture in our bodies, but must get from external sources. The
difference is that we need EFAs in much
larger quantities than we do vitamins. We can eat a small pill every day to
get all the vitamins and minerals we need. We must eat a lot of food to get all
the essential fats we need.
Fats are a mixture of fatty acids:
§
Saturated fatty acids (SFAs), such as beef fat, form
solid foods at room temperature because they are straight molecules and can
pack tightly together.
§
Monounsaturated fatty acids (MUFAs), such as olive oil,
have one “kink” or bend. They form liquid foods at room temperature, but pack
together as solids when refrigerated.
§
Polyunsaturated fatty acids (PUFAs), like flax seed
oil, have 2 or more kinks. They remain liquid even when refrigerated, because
the molecules cannot pack together. Two PUFAs (w3 and w6) are EFAs. Others (w7
and w9) are not EFAs. Dr. Siguel coined the term “essential fats” to refer to
the w3 and w6 PUFAs.
The human body can make MUFAs & SFAs, but not w3 or w6. It is the
unique, kinked shape of PUFAs which allows them to perform their useful
functions in our bodies.
PUFAs can assume many different spatial configurations. Each of these
different spatial shapes is known as an “isomer.” Isomers have the same
number of atoms, but they are arranged in a different way and thus form
different physical structures. The highly unsaturated fatty acids can form more
isomers than the less unsaturated fatty acids. Heat, light, and many physical processes
can change the shape of a PUFA from one isomer to another isomer. As far as we
know, only one form, known as the “cis” form, has the necessary
biological effects. The cis form is usually found in natural foods.
§
Hydrogenation is a process that changes the location of
the hydrogen carbons and causes the molecule to straighten its bend. The new
form of the fatty acid is known as trans fatty acids (TFAs). TFAs are straighter than their
original unsaturated fatty acid and therefore act more like saturated fat than
their original unsaturated fatty acid.
Essential Fats (EFs), a term coined by Dr. Siguel,
consist of two families, omega-3s (w3s) and omega-6s (w6s). The
letter “omega”, abbreviated “w”, refers to the “kinks” or “bends” in EF
chemical structure.
Each family is divided into parents (precursors)
and daughters (derivatives). Using information gained by
distinguishing precursors from their metabolic derivatives, nutritionists can
determine fatty acid needs. Siguel distinguished these groups because there is
interconversion among the derivatives, and the key limiting delta-6-desaturase
enzyme separates them from their precursors.
The two EFAs (the “parents”) are linolenic acid
and linoleic acid. From the EFAs, most humans can make all the EFA
derivatives they need. However, some people (diabetics, alcoholics, the
elderly, infants not breast fed, and people with severe fat malabsorption,
AIDS, cardiovascular disease, or nutritional
deficiencies) cannot make enough EFA derivatives, and must eat them.
“Essential Fats” (EFs)
= EFA precursors + EFA derivatives
= linolenic (w3) + linoleic (w6) + (w3 derivatives) + (w6 derivatives).
PUFAs = PUFA w3 + PUFA w6 + some w9,
mostly with EFA deficiency
The following factors influence the effects of fats and oils
upon your health: the total and proportionate amounts that you eat of saturated,
monounsaturated and essential fats, trans
fatty acids and other isomers, the amounts of antioxidants in your diet, your
exercise level, your metabolism, the state of your health, and your body’s
fatty acid composition.
In general, small amounts of saturated
fatty acids from butter or tropical oils are harmless, particularly if you have
adequate levels of essential fats. TFAs are never harmless, but small amounts
cause insignificant changes in health status. Isomers, which are other types of
fatty acids produced by food processing, may be even more dangerous than TFAs
because the body may not be able to eliminate them. We know very little about
where the isomers and TFAs accumulate in the body, if they do. Very small
amounts of these unusual fatty acids could have an effect out of proportion to
their size if they affect some organs, like the heart, more than other organs.
It is very important to have the right quantity and balance of
EFs in your body. If you eat foods low in EFs, most of
the fat in your body will be solid, your arteries will become hard, and you
will develop hypertension. Eating foods high in EFs maintains soft arteries and
prevents clots.
EFs are used for energy, to make cell membranes, and to
modulate the balance of eicosanoids (hormones which regulate many body
functions). Eicosanoid balance is critical to life (for clot formation, immune
defenses, inflammation, etc.). Nutrients (vitamins and minerals) protect EFs
from oxidation.
Dr. Siguel suggests consuming about 1/3 gram EFs per kg of
ideal body weight [20-30 grams per day for the average man that weighs 150 lbs;
and 15-25 grams for the average woman that weighs 120 lbs]. The proportion of
w3:w6 should be between 1:1 and 1:10. Because EFs accumulate in the body, one
may eat more some days and less other days.
There is huge variability in individual needs. The need for
EFs increases with increased cell turnover (i.e. burns, pregnancy,
gastrointestinal disease, inflammation, growth). Growing children and pregnant
women need proportionately more EFs, particularly w3s, than average adults.
To reduce your chances of becoming deficient in EFs, you
should eat more natural foods in their unprocessed state. These foods are high
in cell membranes, which contain plenty of EFs and the appropriate
antioxidants. Green vegetables, many seeds and oils such as soybean oil, flax,
and wheat germ are often high in EFs. Fish, poultry, and egg yolks contain
mixtures of EFs. Lean meats and eggs from animals fed EF-rich feeds are high in
w3s and w6s. EFs can be added to spreads, desserts, baked
products, salad dressings + many other foods.
In general, the diet that works best for prevention or treatment of CAD may also work to prevent other diseases, including cancer. A low-fat diet can be healthy, but only when eating foods that are intrinsically low in fat and high in EFs.
|
All information on this website is copyrighted; see use and permission to reproduce. The information in this website is not medical advice, merely a general scientific discussion. See warnings & disclaimers. |
|
|
© 1998-9 Edward Siguel. All rights reserved |
modified 1/6/00 |