Monounsaturated
Fat (MUFA)
Monounsaturated fat (MUFA) is fat
that has one double bond in its structure. At room temperature,
MUFA is in an oil and liquid form. When placed in the refrigerator, MUFA will
turn cloudy.
MUFA is derived from plant sources, such as canola (62% MUFA), peanut (49% MUFA)
and olive (77%). Olive oil has the highest content of MUFA among most vegetable
oils. MUFA is also found in olive oil margarine, canola margarine, and peanut
butter.
MUFA
is labeled as a “good” fat and for good reasons.
Studies have shown that for each 10-gram increment intake of monounsaturated
fat in the diet, there is a significant reduction in the relative risk for invasive
breast cancer. One study published in the New England Journal of Medicine
(1197; 278:2145-2150) found that stroke risk declined 11 percent for every 1
percent increase in MUFA intake in our diet.
Epidemiological studies have shown
that people that live in Mediterranean countries have one of the lowest rates
of cardiovascular disease in the world. This population group takes in olive
oil as their main source of fat. Olive oil is high in MUFA. Whether longevity
is directly related to the high olive oil in the diet remains unknown. It has
been postulated so, although there are opposing and conflicting scientific evidence,
including one study where mice and monkeys fed monounsaturated fats - such as
olive oil - developed more hardening of the arteries in major blood vessels
than animals fed polyunsaturated fats.
MUFA’s anti-aging properties include:
a. Lowering the oxidation of
LDL cholesterol and thus, slowing a crucial process of atherosclerotic plaque
formation.
b. Lowering the triglyceride
levels, a form of circulating fat found in plaque and cholesterol.
c. Promoting high level of HDL
cholesterol and hence, decreasing the risk of heart disease.
The largest benefit in terms of reduced
risk of cardiovascular disease is found when SFA are replaced with MUFA. Since
SFA increase risk of heart disease, and MUFA reduce that risk, changing both
at the same time maximizes the benefits.
The following
suggestions are recommended ways to boost MUFA in an anti-aging diet:
a.
Substitute butter with a spread that includes olive oil, which is high in MUFA.
b.
Have hazelnuts for a snack (high in MUFA) as an alternative to cheese (high
in SFA).
c.
Have tossed salad with vinaigrette made from canola oil (high in MUFA), rather
than ranch or Thousand Island dressing (high in SFA).
d.
Cook exclusively with olive (high in MUFA). Olive oil is the best of all oils
for consumption. Use the extra virgin form in a glass that is opaque and store
it away from light to avoid oxidation of the fats in the oil.
Polyunsaturated
Fat (PUFA)
Polyunsaturated fat (PUFA) are fat
made up with fatty acid chains (like linoleic acid and linolenic acid) that
contains two or more double bonds. PUFA are primarily found in vegetable
oils and fish sources. Omega-6 PUFA is derived from vegetable oils. Salad dressing,
margarine, and mayonnaise containing these oils are therefore high in PUFA.
Omega-3 PUFA are found primarily in fish. At room temperature, PUFA is in liquid
form. Even in cold temperatures, PUFA still remains as liquid since it has a
lower melting point than MUFA or SFA.
Cooking
oils (which are natural mixtures of various fatty acids) are mostly a mixture
of MUFA and or PUFA. Olive
oil is a good example of mostly monounsaturated fatty acids (77% MUFA), while
canola oil has 32% PUFA. Most common vegetable oil such as soy (61% PUFA), safflower
(77% PUFA), and sunflower (69% PUFA) oil, are high in polyunsaturated fats.
The push towards PUFA vegetable oil
worldwide from the early 1970s have lead to a tremendous increase in PUFA in
our body. Research studies revealed that natural virgin PUFA lowers cardiovascular
disease risk by 19% in some studies. Unfortunately,
most PUFA consumed these days, like corn, soy, or safflower are often commercially
processed. Their molecular structure is greatly modified. The health enhancement
properties of PUFA have largely been lost in this process.
Original
healthy sources of natural PUFA are found in nuts and seeds. Also, cold water
fish such as salmon contain a good amount of PUFA. The PUFA found in processed
vegetable oil such as corn oil is structurally changed and not good for the
body.
Trans
Fat
Both
MUFA and PUFA tend to be liquid at room temperature. In order to firm them up,
food processors will " hydrogenate" PUFA. This processing results
in a type of fat call trans fat.
Trans fat remains solid at room temperature. They can be then turned into shortening
and margarine. By increasing its resistance to oxidative damage, the oil's shelf
life is extended. Its commercial value is increased.
Trans fat is commonly used in cakes, donuts, fast foods, and fried foods. It
is estimated that Americans consume about 5 grams of trans fat per day, accounting
for about 3 percent of their total calories, according to at 1999
study reported in the Journal of the American Dietetic Association.
While trans
fatty acids may be classified as hydrogenated polyunsaturated fats due to their
chemical structure, they generally are like saturated fats in terms of their
effects on cholesterol.
Without a doubt,
trans fat is the worse kind of fat. During the hydrogenation process,
the chemical structure of the natural fatty acid is changed from their original
cis- configuration to unnatural trans- configuration. Trans-isomerization alters
the 3 dimensional configuration of dietary fatty acid, causing damage to the
cell membranes and altering the function of phospholipid-dependent enzymes contained
in these membranes. This altered fluidity increase cell membrane permeability.
The active transport enzymes for sodium, potassium, calcium, and magnesium are
impaired. Such cell membrane is also subject to free radical attack and damage.
A high intake of trans fat has therefore been linked to a variety of free radical
and degenerative conditions such as cancer, arthritis, and cardiovascular disease.
Trans fat also increases the level
of triglyceride and LDL cholesterol. More significantly, trans fat reduces the
level of "good" HDL cholesterol that often related to the lower risk
of cardiovascular diseases. A study published in the New England Journal
of Medicine reported that trans fat is
linked to a 93% rise in the risk of cardiovascular disease. The research also
revealed that a replacement of 2% of trans fat consumed with MUFA (like nuts,
olive oil and flaxseed oil) could reduce heart disease risk by 53%.
Trans fats should be avoided as
much as possible in our diet. Trans fats are exposed to heat and oxygen during
the frying process results in the worse possible combination of unhealthy fatty
acids. Also, salad oils used in producing salad dressing like mayonnaise
also have excessive amount of lipid peroxides. Studies have shown that the
average woman age 19-50 got more fat from salad dressing than from any other
food!
Naturally
occurring trans fat is quite rare, being limiting to a small amount in milk
as a consequence of gut bacteria in dairy cows. Clearly this is not the kind
of fat Mother Nature intended us to have in our body.
Consumers as a whole are quite ignorant
of the negative effect of trans fat. Look for the term "partially hydrogenated"
to disclose its presence on food labels. Those who try to assess the amount
of trans fat in the food will find it difficult, because the Food and Drug Administration
(FDA) does not require manufacturers to specify the amount of trans fat on the
food label. Margarine, for example, may provide 3 grams of saturated
fat per tablespoon. They are, however, very high in trans fat, with
as much as 3 additional grams per tablespoon. Chocolate chips cookies that contain
only 2 grams of saturated fat according to the label may contain double that
amount of trans fat, though this is not seen on the label. Anytime you see
the word "hydrogenated fat" on the label, you are looking at trans
fat. The easiest way to calculate is to look at the total fat at the label
and subtract the amount of monounsaturated, polyunsaturated, and saturated fat.
Fat and Cholesterol in Food
|
Approximate amount of fat and
cholesterol in Food
|
|
Food Category
|
Serving size
|
Grams fat per serving
|
Cholesterol (mg/dl)
|
|
Dairy
|
|
Ice cream
|
1 cup
|
15
|
60
|
|
Egg, cooked
|
1
|
5
|
210
|
|
Cheddar cheese
|
1 oz.
|
10
|
30
|
|
Meat
|
|
Regular ground beef cooked
|
1 patty
|
15
|
90
|
|
Hot dogs
|
1
|
15
|
35
|
|
Chicken leg w/skin
|
1
|
15
|
105
|
|
Nuts and seeds
|
|
Peanut butter
|
1 Tbsp.
|
10
|
0
|
|
Baked goods
|
|
Doughnut, glazed
|
1
|
10
|
10
|
|
Brownies
|
1 square
|
5
|
15
|
|
Candy
|
|
chocolate
|
1 oz.
|
10
|
10
|
|
Other
|
|
olives, giant size
|
5
|
5
|
0
|
|
* 1 gram of fat or cholesterol
has 9 calories
|
|
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