Essential Fatty Acids

Robin Whittle  rw@firstpr.com.au     3 May 2001

16 September 2003:

I had not made this page public, but now I will, to help with the discussion on the Evolutionary Psychology mailing list http://groups.yahoo.com/group/evolutionary-psychology regarding fish oil, fish, essential fatty acids, and their use in general nutrition, nutrition for pregnant women, and for prisoners, with potential benefits in intelligence, increased head circumference and reductions in violence.  The discussions begin here:

http://groups.yahoo.com/group/evolutionary-psychology/messages/27061

Best to print this landscape, I think.

Summary

• Modern diets do not contain enough of the fatty acids - so Evening Primrose Oil, Fish Oil, Flaxseed Oil and others can contribute significantly to health.
• Overview of the two kinds of essential fatty acid and their molecular structure.
• How these are processed in the body to form intermediate fatty acids and ultimately Prostaglandins 1, 2 and 3.
• How Evening Primrose Oil / Borage Oil and Fish Oil contribute directly to nutrition.
• How some of the other oils contribute as well.
• Benefits of Olive Oil, problems of artificially hydrogenated oils, such as those in margarine, and problems with frying.

There are two types of Essential Fatty Acid (EFA) which are essential to life, known as "Omega 3" (starting point Alpha-Linolenic) and "Omega 6" (starting point Linoleic).  These are two of the fifty or so essential things we must eat, as nicely listed at Al Durtschi's pages, which are derived from Fats that Heal Fats that Kill by Udo Erasmus.

http://waltonfeed.com/omega/50ele.html

Watch out for the "n" in linolenic compared to linoleic!

Fatty acids are explained diagrammatically at:

http://waltonfeed.com/omega/ess_fat.html

I am going to use this information and some diagrams from this page, with various other items I gained from books such as Patrick Holford's The Optimum Nutrition Handbook to summarise the key points.

Please read the above pages before proceeding.  They contain important information, are easy to read, and I am only going to repeat some of it below.

A Saturated Fatty Acid has all its carbons joined by single bonds, with each carbon joining to two hydrogens. (Carbon has 4 bonds, hydrogen one and oxygen 2.) For instance Stearic Acid, as found in beef:
 

There are various degrees of a fatty acid being "unsaturated".  "Unsaturated" means that two of the Hydrogens in the middle of the molecule are missing and that the adjacent Carbons they are missing from form a double bond between themselves.  "Poly-unsaturated" simply means that there are two or more such Carbon double bonds and missing Hydrogens in the main body of the molecule.

The diagram in the table below of Oleic Acid below shows two Hs missing and a double bond between the two adjacent Cs which only have one H, rather than two.  Each H hydrogen atom is in fact a lonely proton, with its electron cloud (think of one electron buzzing around) shared with the C carbon it is bonded to.  The two Hs of these two Cs are therefore positively charged protons without much of a negative electron cloud to balance their positive charge - so they repel each other, bending the molecule.

Because a saturated fatty acid molecule is straight, the molecules pack together closely and the resulting attractive forces make the fat hard to break into a liquid.  Therefore it has a higher melting point.  (I think that saturated fats are more commonly found in warm-blooded mammals than in plants.  Plants live at lower temperatures and so use more unsaturated fats which are liquid at lower temperatures.   However, these molecules are typically not in the bulk liquid form in cells, so their melting temperature is only an indication of their behaviour in the cell.)

There is something of a pattern in some of  names for the various stages of desaturation.
 

Degree of unsaturation	Name of fatty acid	Diagram	Melting  point degrees C.	Essential?
0	Stearic		70
1 (mono- unsaturated)	Oleic		12
2	Linoleic		-5	Essential
3	Linolenic	(Alpha-Linolenic acid)	-12	Essential
4	Arachidonic
5	EicosaPentaecoic (EPA)
6	DocosaHeaenoic (DHA)

Our concern with nutrition is two chemical pathways in our bodies, which together result (amongst other things) in the productions of three groups of prostaglandins, which are regulatory molecules performing a wide variety of functions.  According to The Optimum Nutrition Bible the functions of prostaglandins include:

• Keeping the blood thin - to prevent clots and blockages.
• Relax blood vessels.
• Lower blood pressure.
• Maintain water balance.
• Decrease inflammation and pain.
• Improve nerve and immune system functioning.
• Help insulin work . . .

Prostaglandins are short-lived compounds the body uses to regulate itself.  The body must make them itself - so there is no possibility of prostaglandin supplements.
 

Omega 6 Pathway

Linoleic Acid             (LA)   <<<  Normal sources include Almonds,
                                                Hazelnuts and Pumpkin seeds.

                                 !!!! This conversion is inhibited
                                      by the artificial "trans"
                                      fatty acids found in hydrogenated
                                      vegetable oil products such as
                                      margarine.  Also, people deficient
                                      in Vitamins B3 (niacin), B6
                                      (pyridoxine), zinc and magnesium
                                      will have difficulty with this
                                      conversion.

 converted to:
    |
Gamma-Linolenic Acid      (GLA)  <<<  Evening Primrose and Borage Oils are an
                                                excellent source of GLA, meaning that
                                                less Linoleic Acid is needed.
 

 converted to:
    |
Di-Homo-Gamma-Linolenic Acid (DGLA)
 

 converted to:
    |
Prostaglandins 1 and 2
 

Omega 3 Pathway

Alpha-Linolenic Acid             <<< "Normal sources" include Flaxseed, Hemp and
                                               Pumpkin Oil - but 95% of Americans don't
                                               get enough of these.

 converted to:
    |
  Eicosapeentaecoic Acid  (EPA)  <<< Fish Oil is an excellent
& DecosaHexaenoic Acid    (DHA)  <<< source of EPA and DHA.
 

 converted to:
    |
Prostaglandins 3
 
 

Supplements

If you don't eat a lot of nuts or certain seeds then Evening Primrose Oil or Borage Oil may provide you with Omega 6 essential fatty acids which will make a significant difference to your health.   Evening Primrose Oil is widely believed to assist in alleviating Pre Menstrual Tension, but I haven't looked for or seen any test results to this effect.

If you don't eat fish regularly, then it is likely that Flaxseed Oil or Fish Oil supplements will provide you with Omega 3 essential fatty acids which will make a significant difference to your health.

Patrick Holford, in The Optimum Nutrition Handbook provides the following table.  The idea is to consume one of the items in the left column and one in the right, or some mixture which adds up to the same effect.
 

 

Omega 6	Omega 3
3 to 5% of total calories 10-17 grams a day	2.5 to 5% of total calories 8-17 grams a day
Hemp seed oil  1 tablespoon.	Hemp seed oil  1 tablespoon.
Evening Primrose Oil  1 gram.	Flax seed oil     1 tablespoon.
Borage Oil  500mg.	Flax seeds        2 tablespoon.
Sunflower seeds  1 tablespoon.	EPA/DHA (Fish oil) 1 gram.
Pumpkin seeds 2 tablespoons.	Pumpkin seeds 4 tablespoons.
Sesame seeds 1.5 tablespoons.

Other natural and processed oils

While olive oil does not contain significant quantities of essential fatty acids, cold-pressed olive oil is better than refined vegetable oils such as sunflower oil.

While there is a strong association between cardiovascular disease and the saturated fats (animal fats, high melting point, molecules sticking together, glugging up arteries etc.) of meat and dairy produce (poultry too, I guess) the reverse is true of olive oil.  Olive oil is believed to be an important factor in the relatively low rate of heart disease in Mediterranean countries.

Margarine is made by "hydrogenating" vegetable oils.  This is achieved at high temperature and pressure of hydrogen gas in the presence of a metallic catalyst.  The resulting molecules have a higher melting point, which is the aim of the hydrogenation process, but they are not as useful to the body.  Indeed the resultant very large variety of "trans" structured molecules which result includes many forms which interfere with the body's metabolism of essential fatty acids.   So margarine, and products which contain hydrogenated fats are best avoided.   (I am not sure of the relative benefits of butter or margarine made with olive oil.)  (Try as I may, I can't find a good word for chocolate in all of this . . . )

Frying oxidises the oils, and produced "free radicals" (highly active molecules which may cause cellular damage once ingested, but for which vitamin E and other anti-oxidants are believed to protect against).
 
 

Links

This is a vast field.  These are just a few links.  Proper research would find many more.  See the Evolutionary Psychology list discussion for many new and pertinent links.

http://www.stumptuous.com/fat.html   Weighlifting Mistress Krista on Essential Fatty Acids.

http://www.zooscape.com/cgi-bin/maitred/GreenCanyon/questr100011 Sensible sounding stuff on EFAs.

http://home.online.no/~dusan/foods/udoschoice.html   Udo Erasmus' choice of EFAs.