(http://www.drmcdougall.com/misc/2007nl/aug/oils.htm)
Begin by telling them, �The fat you eat is the fat you wear,� and
remind them that there is nothing attractive about wearing olive,
flaxseed, or corn fat.* For this reason alone, most of your friends and
family should steer clear of so-called �healthy oils� derived from
plant-foods. Gaining weight can be expected from consuming high-fat
whole foods, such as nuts, seeds, avocados and olives, as well as �free
oils,� which are usually purchased in bottles. However, the shared
propensity for weight gain is where the similarity between unprocessed
plant foods and free oils ends.
I consider whole foods, even those with high concentrations of fats,
to be health-promoting. However, people interested in losing weight
should avoid nuts, nut butters, seeds, seed spreads, avocados, and
olives, since they all serve as sources of concentrated, easy to
consume, calories. When I was growing up we had nuts in their shells as
a special treat for Christmas. Now these same nuts come bare-naked,
salted, and sometimes roasted in additional oils�and the twist of the
lid of the jar brings effortlessly to your lips (and your hips) handfuls
of fat-laden, calorie-concentrated rich food. These same foods, however,
may be a welcome addition for growing children and active adults. But
they should be used sparingly by most of us.
Chemically speaking, free oils are chains of carbon found in a
purified state. Extraction processes have removed all of the other
ingredients of the whole food. Thus, free oils are no longer intermixed
with the naturally-designed and balanced environment of proteins,
carbohydrates, vitamins, minerals, and ten thousand other chemicals
found originally in the plants. Free-oils are not food�at best these are
medications, causing some desirable effects, and at worst; they are
serious toxins causing disease.
*The main distinction between fats and oils is whether they�re solid
or liquid at room temperature.
Oils Are Essential for Health
The human body can synthesize from raw materials almost all of the
organic compounds needed to build and maintain itself. However, there
are a few basic elements that it cannot synthesize. These must be
obtained from the food, and include 11 vitamins, 8 amino acids, and 2
kinds of fat. Fortunately, except for two vitamins (vitamin D from the
sun and B12 from bacteria), all of these essential nutrients are made by
plants and found in abundant quantities in a diet based on whole
starches, vegetables, and fruits.
Fats are made of chains of carbon which differ in length, and the number
and positions of double bonds (a chemical term for a dual linkage
between carbon atoms). Animals cannot create double bonds after the
third and sixth carbon on the chain. Only plants can make this
arrangement. The result is that only plants can synthesize omega-3 and
omega-6 fats. These are referred to as �essential fats.� We, like all
other animals, must get these essential fats directly by eating plants
or indirectly by eating animals that ate plants and stored these
essential fats in their tissues. For example, fish store the omega-3
fats made by algae�fish cannot synthesize this kind of fat.
|
Common Fats
(fatty acids)
Linoleic acid is from plants and is the most common kind
of omega-6 fat consumed by people.
Gamma linolenic acid is an omega-6 fat from plants,
and in an isolated form, is used as a medication.
Alpha linolenic acid is from plants and is the most
common omega-3 fat consumed.
Eicosapentaenoic acid (EPA) is an omega-3 fat made by animals,
including fish, from alpha linolenic acid.
Docosahexaenoic acid
(DHA)
is an omega-3 fat made by animals, including fish, from alpha
linolenic acid. |
|
Linoleic |
Alpha
linolenic |
Gama
linolenic |
Eicosapentaenoic |
|
safflower |
flax |
borage |
cold water
marine fish |
|
sunflower |
hemp |
black currant
seed |
|
|
hemp seed |
canola
(rapeseed) |
primrose |
|
|
soybeans |
soybeans |
|
|
|
walnut |
walnut |
|
|
|
pumpkin |
leafy green
vegetables |
|
|
|
sesame |
purslane |
|
|
|
flax |
perilla |
|
|
Essential Fat Deficiency Is Essentially Unknown
In our bodies these plant-derived, essential fats are used for many
purposes including the formation of all cellular membranes, and the
synthesis of powerful hormones, known as eicosanoids (prostaglandins,
leukotrienes, and thromboxanes). Our requirement is very tiny, and even
the most basic diets provide sufficient linoleic acid to meet our
requirement, which is estimated to be 1�2% of dietary energy.1
Therefore, in practical terms, a condition of �essential fatty acid
deficiency� is essentially unknown in free-living populations.*
Essential fatty acid deficiency is seen when sick patients are fed
intravenously by fat-free parenteral nutrition. In these cases,
correction of the deficiency can be accomplished by applying small
amounts of soybean or safflower oil to their skin�giving you some idea
of the small amount of oil we require.2 Plan on your diet of basic
plant-foods supplying an abundance of essential fats delivered in
perfectly designed packages, functioning efficiently and safely.
*Some people talk about a �relative deficiency� of essential fats
created by a large intake of saturated animal fats, synthetic trans fats
(as found in margarine and shortenings), and/or omega-6 fats compared to
their intake of omega-3 fats, and they believe many of our common
chronic diseases are the result of this imbalance.1 This is quite
different from true essential fatty acid deficiency which would result
in: loss of hair, scaly dermatitis, capillary fragility, poor wound
healing, increased susceptibility to infection, fatty liver, and growth
retardation in infants and children.1
Free Oils as Medications
When the oils are removed from their natural environments�for
example, from the seeds of corn, soybeans, safflowers, or flax, or the
fruit of an olive or avocado�they are no longer a food. Yes, they do
supply concentrated calories�but the rest of the original nutrition
found in the plant parts is absent. In this state, the free oils can
display powerful pharmacological effects�some beneficial and some
harmful. This would be analogous to removing vitamins and minerals from
plants and making supplements. I don�t call supplements food, do you?
However, the effects of concentrated, isolated oils are usually even
more potent than those seen with supplements.
Omega-3 and omega-6 oils inhibit the aggregation of platelets,
slowing down the coagulation of the blood�thus these oils �thin the
blood.� This well-known property can be beneficial for reducing the risk
of a blood clot forming in the heart arteries�the cause of a heart
attack. A common practice is to take omega-3 (fish or flaxseed) pills to
reduce the risk of heart disease.3
Omega-3 and omega-6 oils suppress the immune system, reducing
inflammation. As medications they have been tried in autoimmune
conditions such as rheumatoid arthritis, Crohn's disease, ulcerative
colitis, psoriasis, lupus erythematosus, multiple sclerosis, eczema, and
psoriasis.4 Other disorders, such as migraine headaches, Alzheimer�s
disease, and PMS have also been treated. The reports of benefits are
variable and often questionable; as a result, their use has not been
well accepted in most medical practices.
As silly as this may sound, it has been suggested that eating
essential fat may cause people to lose weight. However, a 12-week,
double-blind evaluation of evening primrose oil as an �anti-obesity
agent� on 100 women found no significant difference in the weight loss
achieved by those taking primrose oil compared with placebo.5 Fats (and
oils) are the metabolic dollar stored for the day when food is no longer
available. Even �healthy oils� are moved from the spoon to the flesh
with such efficiency that you should assume every drop you eat makes
that journey.
Free Oils as Toxins
As with all other medications, there are adverse effects from
consuming free oils, when added from a bottle to meals or taken as
pills. The most obvious adverse effect is people gain weight when they
eat even so-called �healthy oils,� like olive oil. When 54 obese women
in a Mediterranean country were studied, these women were found to be
following a diet low in carbohydrates (35% of the calories) and high in
fats (43% of the calories). Of the total calories from fat, 55% came
from olive oil.6 My point: a Mediterranean diet which is loaded with
olive oil, rather than fruits and vegetables, will make you fat. Omega-3
and omega-6 oils thin the blood, which make a person more susceptible to
bleeding.7,8 This side effect from taking essential oils to prevent a
heart attack could become fatal after an automobile accident or if an
artery in the brain were to rupture, such as occurs in a hemorrhagic
stroke.
|
Do
Vegetable Oils Really Prevent Heart Disease?
Common
knowledge is vegetable oils are protective against heart
disease, but there is evidence that questions the real life
benefits:
�
Serial angiograms of people�s heart arteries show that
all three types of fat�saturated (animal) fat, monounsaturated
(olive oil), and polyunsaturated (omega-3 and -6 oils)�were
associated with significant increases in new atherosclerotic
lesions over one year of study.9 Only by decreasing
the entire fat intake, including poly- and monounsaturated-oils,
did the lesions stop growing.
�
Dietary polyunsaturated oils, both the
omega-3 and omega-6 types, are incorporated into human
atherosclerotic plaques; thereby promoting damage to the
arteries and the progression of atherosclerosis.10
�
A study in African green monkeys found when
saturated fat was replaced with monounsaturated fat (olive oil),
the olive oil provided no protection from atherosclerosis.11
�
One of the most important clotting factors
predicting the risk of a heart attack is an elevated factor
VII. All five fats tested�rapeseed oil (canola), olive oil,
sunflower oil, palm oil, and butter�showed similar increases in
triglycerides and clotting factor VII.12
Most likely, the
heart benefits of a Mediterranean diet are due to it being a
nearly vegetarian diet. The Mediterranean diet is a good diet
in spite of the olive oil.13 |
Free oils may be toxic to the body tissues. Both omega-3 and omega-6
fats are associated with an increased risk of opacification of the lens
of the eye, resulting in cataracts.14
Omega-3 and omega-6 oils could benefit people with autoimmune
disorders. On the other hand, excessive intake of these fats may
actually aggravate these disorders.15 More importantly, we
need our immune system functioning at full capacity to fight off
infections and cancer. Free oils have been demonstrated to suppress many
natural microbe killing mechanisms (with a marked decrease in cytokine,
tumour necrosis factor-alpha and interferon-gamma).16
Research on animals suggests the omega-6 variety of oils is very
cancer-promoting and the omega-3 variety may be beneficial for cancer
prevention.17 However, this may not be the case. In one
animal experiment on colon cancer, a fish oil diet and a safflower oil
diet induced, respectively, 10- and 4-fold more metastases (number) and
over 1000- and 500-fold more metastases (size) than were found in the
livers of rats on the low-fat diet.18 Other, animal
experiments also have shown essential fats to be cancer promoting.19,20
Most importantly, population studies tell us that, worldwide, the lower
the total fat intake, the less the risk of common cancers, such as
breast, colon and prostate.21-23
|
Practical
Ways to Eliminate Oils in Cooking
Don�t add vegetable oils when cooking
Use non-stick pots and pans
Brown or soften vegetables in water
Saut� with non-fat liquids
Replace oil in baking with fruit or tofu
Use commercial fat-replacers
Lighten texture with carbonated water
Detailed information on cooking
without oil |
The Final Step
Not a day goes by that I don�t hear someone say to me, �My diet is
completely vegan, but I am still 40 pounds overweight.� The oily sheen
on her face and hair are a clear give away that she hasn�t been willing
to stop adding the half cup of extra virgin olive oil to her spaghetti
sauce. Many people fall short of their health and appearance goals
because they have yet to eliminate all the added vegetable oils from
their cooking. Eating out is a major stumbling block. More often than
not, even after using the best communication skills with the waiter, the
diner plate still glistens with an oil slick. Avoiding free vegetable
oils is the last important hurdle for people seeking better health. Take
the final step�just say �No� to these really unessential added oils.
References:
1) Sanders TA. Essential fatty acid requirements of vegetarians in
pregnancy, lactation, and infancy. Am J Clin Nutr. 1999 Sep;70(3 Suppl):555S-559S.
2) Marcason W. Can cutaneous application of vegetable oil prevent an
essential fatty acid deficiency? J Am Diet Assoc. 2007 Jul;107(7):1262.
3) Mozaffarian D. Does alpha-linolenic acid intake reduce the risk of
coronary heart disease? A review of the evidence. Altern Ther Health
Med. 2005 May-Jun;11(3):24-30;
4) Namazi MR. The beneficial and detrimental effects of linoleic acid on
autoimmune disorders. Autoimmunity. 2004 Feb;37(1):73-5.
5) Haslett C, Douglas JG, Chalmers SR, Weighhill A, Munro JF. A
double-blind evaluation of evening primrose oil as an antiobesity agent.
Int J Obes. 1983;7(6):549-53.
6) Calle-Pascual AL, Saavedra A, Benedi A, Martin-Alvarez PJ, Garcia-Honduvilla
J, Calle JR, Maranes JP. Changes in nutritional pattern, insulin
sensitivity and glucose tolerance during weight loss in obese patients
from a Mediterranean area. Horm Metab Res. 1995 Nov;27(11):499-502.
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Mar;49(3):169-78.
8) Nordstrom DC, Honkanen VE, Nasu Y, Antila E, Friman C, Konttinen YT.
Alpha-linolenic acid in the treatment of rheumatoid arthritis. A
double-blind, placebo-controlled and randomized study: flaxseed vs.
safflower seed. Rheumatol Int. 1995;14(6):231-4.
9) Blankenhorn DH, Johnson RL, Mack WJ, el Zein HA, Vailas LI. The
influence of diet on the appearance of new lesions in human coronary
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fatty acids and composition of human aortic plaques. Lancet. 1994 Oct
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11) Rudel LL, Parks JS, Sawyer JK. Compared with dietary monounsaturated
and saturated fat, polyunsaturated fat protects African green monkeys
from coronary artery atherosclerosis. Arterioscler Thromb Vasc Biol.
1995 Dec;15(12):2101-10.
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dietary fat quality and quantity on postprandial activation of blood
coagulation factor VII. Arterioscler Thromb Vasc Biol. 1997
Nov;17(11):2904-9.
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Am J Clin Nutr. 1995 Jun;61(6 Suppl):1321S-1323S.
14) Lu M, Taylor A, Chylack LT Jr, Rogers G, Hankinson SE, Willett WC,
Jacques PF. Dietary fat intake and early age-related lens opacities. Am
J Clin Nutr. 2005 Apr;81(4):773-9.
15) Namazi MR. The beneficial and detrimental effects of linoleic acid
on autoimmune disorders. Autoimmunity. 2004 Feb;37(1):73-5.
16) Purasiri P, Mckechnie A, Heys SD, Eremin O. Modulation in vitro of
human natural cytotoxicity, lymphocyte proliferative response to
mitogens and cytokine production by essential fatty acids. Immunology.
1997 Oct;92(2):166-72.
17) Sauer LA, Blask DE, Dauchy RT. Dietary factors and growth and
metabolism in experimental tumors. J Nutr Biochem. 2007 Apr 4;
18) Griffini P. Dietary omega-3 polyunsaturated fatty acids promote
colon carcinoma metastasis in rat liver. Cancer Res. 1998 Aug
1;58(15):3312-9.
19) Coulombe J, Pelletier G, Tremblay P, Mercier G, Oth D. Influence of
lipid diets on the number of metastases and ganglioside content of H59
variant tumors. Clin Exp Metastasis. 1997 Jul;15(4):410-7.
20) Klieveri L. Promotion of colon cancer metastases in rat liver by
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Metastasis. 2000;18(5):371-7.
21) Carroll KK. Experimental evidence of dietary factors and
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22) Rao GN. Influence of diet on tumors of hormonal tissues. Prog Clin
Biol Res. 1996;394:41-56.
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diseases based on knowledge of mechanisms. Mutat Res. 1998 Jun
18;402(1-2):331-7
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