The Good, The Bad and The Ugly
Fat is a
headline-maker. Newspapers, magazines and the evening news regularly
attack fat as a contributor to obesity, heart disease and dozens of
other modern diseases. But only part of the story is being told in these
reports. Not all fats are bad. In fact, the essential
fatty acids (EFA), as their name implies, are absolutely essential
for good health.
Facts on Fats
are one of the three categories of dietary macro-nutrients;
the others being carbohydrates and protein. The category of fats is
further divided into the classes of saturated,
monounsaturated and polyunsaturated.
first category of fats, saturated fatty acids, are solid at room
temperature and found in such foods as butter, margarine, beef, chicken
and coconut oil. Saturated fats are responsible for most of the bad
press about fats. As a result the U.S. government, doctors and
nutritionists recommend that Americans limit their intake of
"bad" saturated fats.
second category of fats, monounsaturated fatty acids, are liquid at room
temperature. Monounsaturated fats, such as olive and canola oils, form
the basis of the healthful Mediterranean diet. Monounsaturated oils are
less likely to oxidize than polyunsaturated fats when used for
stir-frying and other cooking.
fatty acids are the third category . Examples of polyunsaturated fats
are flax oil, safflower oil, walnut oil and most other vegetable oils.
Like monounsaturated fats, these oils are liquid at room temperature.
However, polyunsaturated fats break down at high temperatures and should
not be used for high-temperature cooking.
essential fatty acids are found in polyunsaturated fats. The two types
of essential fatty acids are:
Trans-fatty Acids: The Ugly Fats
acids are created from
polyunsaturated fats during exposure to heat or in a process called hydrogenation.
Margarine and other processed fats have undergone hydrogenation to
become trans-fatty acids. As a result, these fats are closer in
composition to saturated fats.*1
long-term effects of trans-fatty acids in the diet are not known, but
some harmful effects have been found.*1,2,3 Women who consume the most
trans-fatty acids have a 50 percent increased risk of heart disease.*2
One study concluded that trans-fatty acids are as bad as saturated fat
since trans-fatty acids reduce levels of the “good” cholesterol
while raising those of the “bad” cholesterol.*1
Why Do We Need Essential Fatty Acids
fatty acids contribute to the maintenance of a healthy body in several
ways. For example, they are an important component of cell membranes,
help insulate the nerves, cushion and protect the tissues, help produce
hormone-like substances called prostaglandins,
and contribute to healthy skin and hair.*
seeds and most vegetable oils are rich sources of the omega-6 fatty
acids. An important type of omega-6 fatty acid, gamma-linolenic
acid (GLA), is found in black currant seed, borage and evening
is an abundant source for omega-3 fatty acids. Eicosapentaenoic
acid (EPA) and docosahexaenoic
acid (DHA) are two types of fatty acids in fish oil; while some
vegetable sources, such as flax oil, contain alpha-linolenic acid.
Apparently, the fatty acids in vegetables can be converted to EPA and
DHA, since these substances are found in the blood of strict
vegetarians.*4 Omega-3 fatty acids are destroyed in the manufacture of
partially hydrogenated vegetable oils.
Benefits of Omega 3 Fatty Acids
the cardiovascular system may be the most important benefit of omega-3
fatty acids.* Fish oil helps regulate cholesterol and triglyceride levels in the blood.*5 Years ago, scientists were
impressed by the healthy cardiovascular systems of Greenland Eskimos,
such as their low triglycerides, moderate cholesterol levels and
“thinner” blood, which was slower to clot. When researchers examined
their diets, they discovered the unusual fatty acids EPA and DHA derived
from a diet based on fish, seal and walrus.6, 7
with greater amounts of omega-3 fatty acids in their diets are also more
likely to have healthy hearts.*8 Adding fish oil, EPA or DHA to the
diets of Europeans or Americans has been shown to produce the same
desirable blood “thinning” effect seen in Eskimos.*9
a few studies have not found a significant heart-protective effect from
eating fish.10 11 However, these few negative trials do find that people
who eat some fish have a trend toward healthier cardiovascular
fatty acids lessen the amount of pro-inflammatory prostaglandins made in
the body,12 which lessens
the painful inflammatory response.*13 Both DHA and EPA reduce levels of
a specific prostaglandin, called prostaglandin-E2, which would otherwise
interfere with proper immune function.*14
addition, omega-3 fatty acids help maintain soft, smooth skin. Diets
deficient in this essential fatty acid result in unhealthy, scaly skin.
Adding omega-3 fatty acids back into the diet provides relief from this
troubling skin condition.*15
Benefits of Omega 6 Fatty Acids
fatty acids are the most common type of fat in the average diet. The
omega-6 fatty acids, linoleic, arachidonic,
and gamma-linolenic (GLA) fatty acids, act as precursors to the majority
of prostaglandins. Omega-6 fatty acids are key structural components of
cell membranes, and are an integral part of the myelin
sheath, which protects nerves.16
to several double-blind research studies, GLA-rich black currant seed,
evening primrose seed and borage oils help reduce swelling and
inflammatory response in joints*4, 17, 18, 19a by significantly reducing
the body’s production of pro-inflammatory prostaglandins and leukotrienes.*17
The GLA dosages used in research studies varied from 480 mg to 1,500 mg
acid may help reduce elevated levels of cholesterol and triglycerides
when supplements of 3,000 mg of GLA-rich oil are taken daily.*20 GLA has
also been shown to significantly decrease blood-clotting.*20
Ideal Intake of Essential Fatty Acids
on a traditional diet consume approximately 5 grams of omega-3 fatty acids daily, which is equivalent to about a pound of
salmon. Yet, men including as little as one-half pound of fatty fish in
their diet every week were found to have healthier cardiovascular
systems compared to non-fish eaters.*21 Researchers from Sweden report
that fish has a “dose-dependent” effect; that is, the more fish in
your diet, the healthier your heart.*22 While optimal intake of omega-3
fatty acids remains unknown, some researchers recommend a daily intake
of 3,000 mg. *23, 24
prevent a deficiency in adults, about two percent of daily calories
should be derived from omega-6
fatty acids. This is equivalent to approximately 4.5 grams of omega-6
fatty acids. Since vegetable oils contain an average of 60 percent
omega-6 fatty acids, about 2 teaspoons of oil should be adequate to
prevent deficiencies. Nutritionists do not know the optimal intake of
omega-6 fatty acids, however, most Americans are believed to consume
et al. Effect of dietary trans fatty acids on high-density and
low-density lipoprotein cholesterol levels in healthy subjects. N
Engl J Med, 1990; 323:439-45.
et al, Intake of trans fatty acids and risk of coronary heart
disease among women. Lancet, 1993; 341:581-5.
et al, Trans-fatty acid intake in relation to serum lipid
concentration in adult men, Am J Clin Nutr, 1992; 56:1019-24.
DeLuca P, Zurier RB, Botanical lipids: effects of inflammation,
immune responses, and rheumatoid arthritis. Semin
Arthritis Rheum 1995;25(2):87-96.
n-3 fatty acid requirements of the newborn, Lipids,
Bang HO. Haemostatic function and platelet polyunsaturated fatty
acids in Eskimos. Lancet
et al. n-3 fatty acids in adipose tissue and coronary artery disease
are inversely related. Am J Clin Nutr 1992;55:1117-9.
Weber PC. Cardiovascular effects of n-3 fatty acids. N Engl J Med 1988;318:549-57 [review]
et al. Fish consumption and cardiovascular disease in the
Physicians’ Health Study: a prospective study. Am
J Epidemiol 1995;142:166-75.
et al. Dietary intake of marine n-3 fatty acids, fish intake, and
the risk of coronary disease among men. N
Engl J Med 1995;332:977-82.
et al. Intake of mercury from fish, lipid peroxidation, and the risk
of myocardial infarction and coronary, cardiovascular, and any death
in Eastern Finnish Men. Circulation
Roshani F. The influence of different types of n-3 polyunsaturated
fatty acids on blood lipids and platelet function in healthy
volunteers, Clin Sci 1983;
Rothman D, and Zurier RB: Marine and botanical lipids as
immunomodulatory and therapeutic agents in the treatment of
rheumatoid arthritis. Rheum
Dis Clin North Am 1995;21(3):759-775.
et al. Eicosapentaenoic acid and prevention of thrombosis and
atherosclerosis? Lancet 1978;ii:117-9.
research by Dr. M.J. James, Rheumatology Unit at Royal Adelaide
Hospital in Australia.
Lipids. In Present Knowledge in Nutrition, ILSI,
1990, pp 63.
LJ, Boyce EG, Zurier RB, Treatment of rheumatoid arthritis with
gamma linolenic acid. Ann
Intern Med 1993;119(9):867-73.
S, Laposata M, Lem D, Holman RT, Leventhal LJ, DeMarco D, Zurier RB,
Alteration of the cellular fatty acid profile and
the production of eicosanoids in human monocytes by gamma-linolenic
acid. Arthritis Rheum 1990;33(10):1526-33.
LJ, Boyce EG, Zurier RB. treatment of rheumatoid arthritis with
black currant seed oil. Br J
M, Meza N, Barja P, Roman O, Clinical and experimental study on the
long term effect of gamma-linolenic acid on plasma lipids, platelet
aggregation, thromboxane formation and prostacyclin production. Prostaglandins
Leukot Essent Fatty Acids 1994;51(5):311
D., et al. The inverse relation between fish consumption and 20-year
mortality from coronary heart disease. N
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S.E., et al. Fish consumption and mortality from coronary heart
disease. BMJ 1986;293:426.
et al. Does supplementation of diet with ‘fish oil’ reduce blood
pressure? A meta-analysis of controlled clinical trials. Arch
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Geusens, P., et al. Longer-term effect of omega-3 fatty acid
supplementation in active rheumatoid arthritis: a 12-month,
double-blind, controlled study.
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