high level of LDL cholesterol reflects an
increased risk of heart disease. That is why
it is called the "bad cholesterol".
is believed to help remove excess cholesterol
from atherosclerotic plaques and thus slow
comes from two sources. It's produced in your
body, mostly in the liver (about 1,000 milligrams
a day). And it's found in foods that come from
animals, such as meats, poultry, fish, seafood
and dairy products.
American Heart Association recom-mends that
your average daily intake of dietary cholesterol
should be less than 300 milligrams.
Remember, it is found only in foods from animals.
Al-though it's not the same as a saturated fatty
acid, dietary cholesterol can also raise your
blood cholesterol level.
You need cholesterol for your body to function
normally, but your body makes enough so that
you don't need to get more from the foods you
Cholesterol produced in you body is a soft,
waxy substance found among the lipids (fats)
in the bloodstream and in all your body's cells.
It's an important part of a healthy body because
it's used to form cell membranes, some hormones
and other needed tissues. But a high level of
cholesterol in the blood - hypercholesterolemia
- is a major risk factor for coronary heart
disease, which causes heart attacks. Cholesterol
and other fats can't dissolve in the blood.
They have to be transported to and from the
cells by special carriers of lipids and proteins
called lipoproteins. There are several kinds,
but the ones to be most concerned about are
low density lipoprotein (LDL) and high density
Dietary cholesterol is found in meat, poultry,
seafood and dairy products. Foods from plants
- such as fruits, vegetables, vegetable oils,
grains, cereals, nuts and seeds - don't contain
cholesterol. Egg yolks and organ meats are high
in cholesterol. Shrimp and crayfish are somewhat
high in cholesterol. Chicken, turkey and fish
contain about the same amount of cholesterol
as do lean beef, lamb and pork.
Low Density Lipoproteins
Low density lipoprotein is the major cholesterol
carrier in the blood. When a person has too much
LDL cholesterol circulating in the blood, it can
slowly build up within the walls of the arteries
feeding the heart and brain. Together with other
substances it can form plaque, a thick, hard deposit
that can clog those arteries. This condition is
known as atherosclerosis. The formation of a clot
(or thrombus) in the region of this plaque can
block the flow of blood to part of the heart muscle
and cause a heart attack. If a clot blocks the
flow of blood to part of the brain, the result
is a stroke. A high level of LDL cholesterol reflects
an increased risk of heart disease. That is why
LDL cholesterol is often called "bad"
cholesterol. Your doctor can judge your risk of
heart attack more accurately by determining the
amount of cholesterol carried by your LDL's. If
your LDL cholesterol is more than 160 milligrams
per deciliter of blood (mg/dL), it's high risk
if you have 2 or more risk factors or if you have
heart disease. Ideally, your LDL cholesterol is
below 130. Total blood cholesterol can indicate
your level of risk. If it's 200 mg/dL or over,
your doctor will probably measure your LDL cholesterol
level, which is a more accurate indicator of heart
High Density Lipoproteins
About one-third to one-fourth of blood cholesterol
is carried by high density lipoprotein or HDL.
Medical experts think HDL tends to carry cholesterol
away from the arteries and back to the liver,
where it's passed from the body. Some experts
believe HDL helps remove excess cholesterol from
atherosclerotic plaques and thus slows their growth.
HDL is known as "good" cholesterol because
a high level of HDL or high density lipoproteins
helps to protect against heart attack.
Raises Your Blood Cholesterol?
You've probably heard the old saying "you
are what you eat" a thousand times. Well,
when it comes to what you eat, three main factors
raise your blood cholesterol level. These are
saturated fats, cholesterol and obesity.
All fats are composed mainly of triglycerides.
These, in turn, are composed of "fatty acids."
These fatty acids fall into three categories:
saturated, monounsaturated and polyunsaturated.
Of these three, saturated fatty acids are the
main culprit in raising blood cholesterol.
high in saturated fat come from both animals and
plants. Animal-based foods containing lots of
saturated fat include butter, beef tallow, lard
and poultry fat. Seafood contains a small amount.
Plant-based oils containing saturated fat include
coconut oil, palm kernel oil, palm oil and cocoa
are four kinds of fats in the foods we eat: (1)
saturated, (2) polyunsaturated,
(3) monounsaturated, and (4) trans fatty acids.
Most foods contain all three types of fat, but
in varying amounts. Saturated fatty acids, trans
fatty acids and dietary cholesterol raise blood
Saturated fatty acids have all the hydrogen the
carbon atoms can hold. Saturated fats are usually
solid at room temperature and they are more stable
- that is, they do not combine readily with oxygen.
Saturated fatty acids are the main dietary culprit
in raising blood cholesterol. The main sources
of saturated fatty acids in the typical American
diet are foods from animals and some plants.
Foods from animals that have high amounts
of saturated fatty acids include beef, beef fat,
veal, lamb, pork, lard, poultry fat, butter, cream,
milk, cheeses and other dairy products made from
whole milk. These foods also contain dietary cholesterol.
Foods from plants that contain high amounts
of saturated fatty acids include coconut oil,
palm oil and palm kernel oil (often called tropical
oils) and cocoa butter.
Trans Fatty Acids
A fatty acid molecule consists of a chain of carbon
atoms in carbon-carbon double bonds with hydrogen
atoms "attached." In nature, most unsaturated
fatty acids are cis fatty acids, meaning the hydrogen
atoms are on the same side of the double carbon
bond. In trans fatty acids the two hydrogen atoms
are on opposite sides of the double bond.
Trans double bonds also occur in nature as the
result of fermentation in grazing animals. People
eat them in the form of meat and dairy products.
Trans double bonds are also formed during the
hydrogenation of either vegetable or fish oils.
To make foods that will stay fresh on the shelf
or to get a solid fat product, such as margarine,
food manufacturers hydrogenate polyunsaturated
oils. Hydrogenate means to add hydrogen. When
unsaturated fatty acids are hydrogenated, some
of the hydrogen atoms are added on opposite sides
of the molecule to the already attached hydrogen.
Cis double bonds convert to trans double bonds,
and the fatty acids become saturated.
In clinical studies, trans fatty acids or hydrogenated
fats tend to raise total blood cholesterol levels
but not as much as more saturated fatty acids.
Trans fatty acids also tend to raise LDL ("bad")
cholesterol and lower HDL ("good") cholesterol
when used instead of cis fatty acids or natural
oils. These changes may increase the risk of heart
disease. It's not clear if trans fats that occur
naturally have the same effect on cholesterol
and heart disease as those produced by hydrogenation
of vegetable oils.
Because there are no standard methods, it's difficult
to estimate the trans fatty acid content of food
items. It's also difficult to estimate intake,
especially long-term intake. On the basis of current
data, the American Heart Association recommends
that consumers follow these tips:
Use naturally occurring, unhydrogenated oil such
as canola or olive oil when possible.
Look for processed foods made with unhydrogenated
oil rather than hydrogenated or saturated fat.
Use margarine as a substitute for butter,
and choose soft margarines (liquid or tub varieties)
over harder, stick forms. Shop for margarine with
no more than 2 grams of saturated fat per tablespoon
and with liquid vegetable oil as the first ingredient.
French fries, donuts, cookies and crackers
are examples of foods that are high in trans fatty
Polyunsaturated and Monounsaturated Fatty Acids
Polyunsaturated and monounsaturated fatty acids
make up the total of unsaturated fatty acids.
Unsaturated fatty acids have at least one unsaturated
bond - that is, at least one place that hydrogen
can be added to the molecule. They are often found
in liquid oils of vegetable origin.
Polyunsaturated oils are liquid at room temperature
and in the refrigerator. They easily combine with
oxygen in the air to become rancid. Common sources
of polyunsaturated fatty acids are safflower,
sesame and sunflower seeds, corn and soybeans,
many nuts and seeds and their oils.
Monounsaturated oils are liquid at room
temperature but start to become solid at refrigerator
temperatures. Peanut oil, olive oil, canola oil
and avocados are sources of monounsaturated fatty
Polyunsaturated fatty acids tend to help the body
get rid of newly formed cholesterol. Thus, they
keep the blood cholesterol level down and reduce
cholesterol deposits in artery walls. Recent research
has shown that monounsaturated fatty acids may
also help reduce blood cholesterol as long as
the diet is very low in saturated fat.
Both types of unsaturated fatty acids may help
lower your blood cholesterol level when used in
place of saturated fatty acids in your diet. But
you should be moderate in your intake of all types
- or monounsaturated oils - and margarines and
spreads made from these oils - should be used
in limited amounts in place of fats with a high
saturated fatty acid content, such as butter,
lard or hydrogenated shortenings.
During food processing, fats may undergo a chemical
process known as hydrogenation.Hydrogenate means
to add hydrogen, or, in the case of fatty acids,
to saturate. The process changes a liquid oil,
naturally high in unsaturated fatty acids, to
a more solid and more saturated form. The greater
the degree of hydrogenation, the more saturated
the fat becomes. Many commercial products contain
hydrogenated or partially hydrogenated vegetable
Recent studies suggest that these fats may raise
blood cholesterol. Hydrogenated fats in margarine
and other fats are acceptable if the product contains
no more than 2 grams of saturated fatty acids
per tablespoon. The fatty acid content of most
margarines and spreads is printed on the package
Fatty Acid Facts
Recent studies on the potential cholesterol-raising
effects of trans fatty acids have called attention
to the benefits versus risks of choosing certain
foods over others. For example, stick margarines
are known to contribute more trans fatty acids
than non-hydrogenated oils or other fats. This
has raised public concern about the use of margarine
and whether other options, including butter, might
be a better choice.
are some facts:
Because butter is rich in both saturated
fat and cholesterol, it is potentially a highly
atherogenic food (causes the arteries to be blocked).
Most margarine is made from vegetable fat and
provides no dietary cholesterol.
The more liquid the margarine, i.e., tub
or liquid forms, the less hydrogenated it is and
the less trans fatty acids it contains. Therefore,
margarine is still a preferable substitute for
butter and soft margarines are better than hard
The American Heart Association recommends
that consumers shop for margarine with no more
than 2 grams of saturated fat per tablespoon and
with liquid vegetable oil as the first ingredient.
They should choose soft margarines over stick
forms to limit their intake of cholesterol-raising
trans fatty acids. Diet or lite margarine has
less fat, hence, trans fatty acids, than regular
margarine and is a preferable choice.
AHA's Nutrition Committee will continue to monitor
research in this area. The committee again strongly
advises that healthy Americans over the age of
2 limit their total fat intake to no more than
30 percent of total calories. If people limit
their daily intake of fats and oils to 5-8 teaspoons,
they are not likely to get an excess of trans
From the American Heart Association
you begin any exercise or diet program, you should have permission
from your doctor.
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