ARE POLY-UNSATURATED FATS GOOD FOR YOU ?
By Dr. Harold Gunatillake
|Fats are needed
by the body in small amounts for important functions. Some dietary fats
are healthier than others. Replacing saturated fats with unsaturated
fats helps lower blood cholesterol levels. Most unsaturated fats come
from plant sources. Like all types of fats, they should be eaten in
Fats are classified in many ways. The simplest classification to understand is the separation of them according to the vacancies for "Hydrogen" atoms in each fatty acid component (chain of carbon atoms). When the component fatty acids (fatty acids are the building blocks of fats) are fully saturated with hydrogen atoms, with no vacancies, we then label them as 'Saturated fats’. When each fatty acid component has one vacancy to be filled with an hydrogen atom, we label as ‘mono-unsaturated fats’, and when many vacancies are present, ‘poly-unsaturated fats’. To further illustrate the difference between these terms, picture a fat molecule as a train of passenger cars. If every seat on the train is filled with a “passenger” (hydrogen atom), then this is a saturated fat molecule ( all carbon atoms are bonded with hydrogen atoms). If there is one seat vacant in each car where a hydrogen atom “passenger” can sit, the molecule is monounsaturated; if there are several seats available, it’s polyunsaturated.
Researchers classify fatty acids not only according to their degree of saturation but also by their lengths (chains).
Short-chain fatty acids have four to six carbon atoms. These fats are stable and are always saturated. They do not become rancid when exposed to air ( no oxidation), Four carbon butyric acid found in butter fat from cows, and six carbon capric acid found in goats milk, are such short chain fatty acids. These fatty acids have anti-microbial properties, that is, they protect us from viruses, yeasts and pathogenic bacteria in the gut. (Why don’t we drink goat’s milk anymore?) Incidentally, capric acid, is also a component of the fats in coconut kernel, and has similar properties. These short chain fatty acids are directly absorbed from the gut, without the assistance of bile salts, unlike the long chain counterparts. In the liver, they are metabolized quickly without being stored as fats. They do not gain weight unlike the long chain fatty acids in olive oil (oleic acid) and commercial vegetable oils. These short chain fatty acids also boosts your immune system.
Medium chain fatty acids have eight to twelve carbon atoms and are found mostly in tropical oils. Like the short chain fatty acids, they also have anti-microbial properties, absorbs directly from the gut, and are converted to energy in the liver. Hence the short chain and medium chain fatty acids are unlikely to produce cholesterol, or stored in the body for future usage.
Coconut oil a good example of a medium chain fat.
Coconut is a saturated medium chain fat, and the liver metabolises it as fast as you eat. It is not stored in tissue. It does not form cholesterol in the liver, and transport and settle down in the coronary blood vessels as bad cholesterol (LDL-cholesterol). It does not promote platelet stickiness, which leads to blood clot formations (strokes, heart attacks). Does not lead to thickening of blood vessels (atherosclerosis). Coconut fat does not promote cancer, or any other degenerative disease. It also helps control diabetes, supports immune system function. Helps to prevent osteoporosis, helps support healthy metabolic function. Provides an immediate source of energy, supplies fewer calories than other fats, and today in the States is recommended as a slimming diet and advertised as “coconut diet”.
Coconut supplies important nutrients necessary for good health. It destroys through its fatty acids- Lauric, capric and myristic acids, many bacteria, viruses, protozoa, and fungus. It has been recognised that one of the functions of coconut is to improve the health of mankind.
Long-chain fatty acids– have 14 to 18 carbon atoms, and can be mono-unsaturated, poly-unsaturated, or saturated. Oleic acid in olive oil is a long chain fatty acid. Some of the other long chain fatty acids are the essential fatty acids, which I will mention in this article.
Poly-unsaturated fats- Now that we have classified fats briefly, let us talk about the fats that we have been asked to eat by the promoters.
During the early part of this century, the rich in Europe ate the expensive butter made from dairy milk, whilst the poor ate cheap margarine made of meat suet, milk and water. By the middle of the 20th century an emulsion of soya bean was substituted for milk, and the oils changed to ground nut, cotton seed, sunflower,and other vegetable seeds.
Thus from an era of eating saturated fats from meat sources, the trend changed to eating more poly-unsaturated fats from vegetable seeds, quite regularly, in margarine and processed foods.
It was said that saturated fats increased the bad cholesterol (LDL) in the blood allegedly leading to heart disease. A researcher in Minnesota announced that heart disease epidemic was caused by hydrogenated vegetable fats. About the same time a researcher in Philadelphia reported that consuming polyunsaturated fatty acids lowered serum cholesterol. In 1953, an American, Ancel Keys, compared levels of heart disease in seven countries with amounts of fats consumed in those countries, and to reduce the incident of heart disease he recommended cutting down on margarine and vegetable oils.
margarine is made totally from poly-unsaturated
vegetable oils such as
sunflower, safflower, soybean, corn, among others.
Poly-unsaturated fats become rancid at room temperature within
days, due to its unstable quality. They have to be hydrogenated to
be preserved to increase the shelf life. This process of hydrogenation
preserves and solidifies the oils. This man modified oil is
referred to as a trans-fat,
which is hardly available in nature, other than small quantities in
first process in the manufacture of margarine is the extraction of
the oils from the seeds, and this is done using petroleum
based solvents at very high temperatures, as much as 160C.
Similar solvents like benzene , known to cause cancer was found in
Perrier mineral water and it went off the market. The oil goes through
many processes– neutralization, de-gumming, deodorization, emulsification,
hydrogenation, etc. Nickel, a metal that used to cause cancer is used
as a catalyst in the process.
margarine goes through all these processes it is nothing but natural
goodness. Labels carry as
and cholesterol free, natural and goodness”.
is true that saturated fats cause increase production of bad LDL cholesterol
in the liver, whilst poly-unsaturated fats lower LDL cholesterol and
increases the good HDL cholesterol. The poly-unsaturated fats in margarine
are hydrogenated fats or trans-fats,
the unsaturated fat goes through a process where hydrogen gas is infused
under pressure in firming it up into a semi-hard or solid form at
room temperature. Today
it is known that trans-fats produce more LDL cholesterol in the blood
than the saturated counterpart, the reason been that the trans-fats
are more saturated and stable than saturated fats in the body.
what does this means for your health!
margarine, butter is not made from hydrogenated oil. Butter prepared
from dairy cream, contains saturated fat and, because it’s made from
animal source, it also has cholesterol.
best for you between butter and margarine is a puzzle. The focus has
been on whether trans-fatty margarines, or is not, preferable to the
saturated fat and cholesterol content of butter. Saturated fats also
cause some forms of cancer, and trans-fats in margarine also increases
the LDL cholesterol and reduces the good HDL cholesterol. Both are
damaging. So, you are between the devil and the deep blue sea. The
choice is yours. The solution is to stick to margarines made of highly
mono-unsaturated oils such as olive and canola oils.
analysis of the plaques (atheromas) that block the coronary arteries,
shows that 24% of the cholesterol esters are saturated fats, and 74%
are poly-unsaturated, possibly partly from the trans-fats.
None of the saturated fatty acids were reported to be lauric acid
or myristic acid found in coconut fat (Felton et. Al 1994)
Canada and United States from this year will require labeling of trans
fatty acids. The producers of trans-fatty acids have relied on the
anti-saturated fat crusade to protect their markets.
fats can be divided into two major classes– omega-6 and omega-3 fatty
acids. The main fatty acid in omega-6, is linoleic acid (LA). This
is an essential fatty acid and cannot be made in the body. The modern
western diet is abundant in LA– rich
poly-unsaturated oils in sunflower, Corn, Cotton seed, Sesame,
Grape-seed, Soybean, and many others. We have been told that these
poly-unsaturated oils are good for you, and that saturated fats cause
cancer and heart disease. So there is a fundamental change in our
Today we consume over 30% of our calorie requirement from poly-unsaturated
fats. We are now told the daily requirement should be limited to 2%
omega-3 and 2% of omega-6 fatty acids. Increased amounts of the omega-6
poly-un-saturates have contributed to many diseases, like cancer,
heart disease, and immune system dysfunction; damage to liver, reproductive
organs and lungs: depressed learning ability, and impaired growth.
reason why poly-unsaturated fats cause many health problems is that
they tend to become oxidised or rancid when exposed, thus giving out
free radicals. We also know that LDL cholesterol found in atheromatous
plaques are quite innocent, and do not
give trouble, until the free radicals acting on them, in the
blood makes it unstable and soft. Then the neighbouring immune cells
in the blood vessel lining
engulfs these unstable LDL cholesterol and turns into foam cells.
These foam cells block the vessels and cause early angina, and heart
acid, the main fatty acid in omega-6 poly-unsaturated fats, brakes
down to arachidonic acid (AA), which gives aggressive omega-6 eicosanoids.
These eicosanoids give out thromboxane– which promotes blood clotting;
leukotrienes which constricts blood vessels; prostaglandins which
promotes inflammation in the tissues.
In 1991, two studies, from USA and Canada, found linoleic acid
(LA) the major polyunsaturated fatty acid found in vegetable oils,
increased the risk of breast tumours. This it seems, was responsible
for the rise in the cancer in the humans.
fats are greatly immuno-suppressive. What this means is that they
prevent the body defensive
system doing its duties to safeguard the
body. Thus any system that suppresses the immune system is
likely to cause cancer. The first person to suggest that polyunsaturated
fats cause cancer was Dr.R.A.Newsholme of Oxford University, England.
He said that when our bodies get sufficient nutrition, our diet includes
immunosuppressive polyunsaturated fats which makes us prone to
infection by bacteria and viruses. When we are starved, however,
our body stores of polyunsaturated fats are depleted. This allows
our bodies’ immune systems to recover which in turn, allows us to
fight existing infection
and prevent other infections. He also said that this effect of polyunsaturated
fats in sunflower seeds can treat autoimmune diseases such as multiple
sclerosis, and that the same fatty acids could be used to suppress
the immune system to prevent rejection of kidney transplants.
kidney transplant patients were fed with polyunsaturated fats in vegetable
oils, the incidence of cancer of these patients went up by twenty
times as was expected.
it has to be inferred that margarine containing hydrogenated polyunsaturated
fats from vegetable seeds may be partly responsible for the high incidence
of cancer, among those who
daily consume this product.
fatty acids is
the other important component
of polyunsaturated fats, much has been written and discovered in the
recent past. You may call it a “Omega-3 Life Style” as its importance
in the longevity process is immeasurable. In the plant foods Omega-3
fatty acids are usually in the form of the shorter chain alpha-linolenic
acid (ALA). Marine Omega-3 in fish are present as longer chain eicosapentaenoic
acid, (EPA), and docosahexaenoic acid, (DHA).
vegetarian diet is a healthy
way of eating. However, plant foods commonly eaten by these vegetarians
do not contain the long chain omega-3 fatty acids, EPA and DHA. For
them there is omega-3 eggs (not available here), which provides a
good source of both EPA and DHA. Like linoleic acid (LA) in omega-6
fatty acids, alpha linolenic acid (ALA), is the main fatty acid in
omega-3 oils. Like LA, ALA is an essential fatty acid. It seems that
the modern western diet lacks ALA– rich sources such as, linseeds,
mustard-seed oil, canola oil, and many others. ALA produces eicosapentaenoic
acid (EPA) which brakes further down to ‘soothing omega- eicosanoids,
such as thromboxanes, leucotrienes, and prostaglandins. EPA and DHA
are important in preventing and treating heart disease, reducing
inflammation, and preventing cancer.
These oils lower the bad
LDL cholesterol, and elevates the good HDL cholesterol, and
also helps brain growth and development Rich sources of omega-3 fatty
acids are fish, sea food, omega-3 eggs, and plants like flax seed,
nuts and legumes. Among the
popular good sources of omega-3 oils from fish, are sardines, herrings,
mackerel, bluefish, tuna, salmon, pilchard, butterfish and pompano.
will notice that both omega-6 and omega-3 oils produce eicosanoids,
but they have different and opposing effects in our bodies. Eicosanoids
produced from omega-6 oils promote blood clotting, inflammation, and
constricts blood vessels, whilst the same fatty acids from
omega-3 oils reduces blood clotting, reduces inflammatory processes,
and dilates blood vessels.
the value of eating more
omega-3 oils, and less of omega-6 oils, in polyunsaturated fats, for
health and longevity cannot be neared. 1000grams of omega –3 oil is
the recommended dose, but one could increase it three times more.
It is available in capsule forms, but the 1000gram capsules may have
to be obtained from abroad through your friends.
it must be stressed that omega-3 oils creates a soothing environment
in our body, calms an over-reactive immune system, in addition to
the above mentioned functions.
begin now, and change your body life style. Switch over from sunflower
oils to canola oil. Change polyunsaturated margarine to canola margarine.
Substitute oily fish three times a week to meat products. Eat nuts,
legumes, and other seeds regularly, in addition to fresh vegetables
and fruits. Walk everyday for half an hour. Avoid those processed
foods in your favourite super market.
is your omega life style, and a healthy longevity is guaranteed.
|Ref: Omega-3 life program, by Shamala Ratnesar, Publisher McGraw Hill: Dr Joseph Mercola’s Newsletter-Aug/2002; www.second-opinions.co.uk/fats and cancer.html: Coconut in support of good health by Mary G.Enig