Blood Cholesterol
-- Guy
Slowik FRCS
What
Is Cholesterol?
Cholesterol is a waxy, fat-like
substance that is made in the body by the liver. Cholesterol forms part of
every cell in the body and serves many vital functions. Our bodies need
cholesterol to:
·
Maintain
healthy cell walls
·
Make
hormones (the body's chemical messengers)
·
Make
vitamin D
·
Make
bile acids, which aid in fat digestion
Sometimes, however, our bodies make
more cholesterol than we really need, and this excess cholesterol circulates in
the bloodstream. High levels of cholesterol in the blood can clog blood vessels
and increase the risk for heart disease and stroke.
· Our
bodies can make too much cholesterol when we eat too much saturated fat - the
kind of fat found in animal-based foods such as meat and dairy products.
· In
addition to making cholesterol, we also get a small percentage of our body's
cholesterol from the foods we eat. Only animal-based foods such as meat, eggs,
and dairy products contain cholesterol. Plant foods such as fruits, vegetables,
and grains do not contain cholesterol.
The
Different Types Of Cholesterol
There are different types of
cholesterol - and not all cholesterol is harmful.
·
Low-density
lipoprotein (or LDL)
cholesterol is a bad type of cholesterol that is most likely to clog blood
vessels, increasing your risk for heart disease.
· High-density
lipoprotein (or HDL)
cholesterol is a good type of cholesterol. HDL cholesterol helps clear the LDL
cholesterol out of the blood and reduces your risk for heart disease.
Facts
About Cholesterol
·
More
than one-half of American adults have blood cholesterol levels that are too
high.
· Lowering
your cholesterol level has a double payback: For every one percent you lower
your blood cholesterol level, you reduce your risk for heart disease by two
percent.
· Even
if you already have heart disease, lowering your cholesterol levels will
significantly reduce your risk for death and disability.
· As
blood cholesterol exceeds 220 ml/dl (milligrams per deciliter, which are the
units in which blood cholesterol is measured in the United States), risk for
heart disease increases at a more rapid rate.
· All
adults should have their blood cholesterol level measured at least once every
five years.
· The
liver makes most of the cholesterol in our bodies-only a small percentage comes
from food. But the more saturated fat we eat, the more cholesterol our bodies
make.
· Most
people can bring down their blood cholesterol levels without medication by
changing the way they eat and by becoming more active.
· Only
animal foods contain cholesterol; plant foods do not contain cholesterol.
· A
medium egg contains about 213 milligrams of cholesterol, a three-ounce portion
of lean red meat or skinless chicken contains about 90 milligrams of
cholesterol, and a three-ounce portion of fish contains about 50 milligrams of
cholesterol.
What
Causes High Blood Cholesterol?
Many factors can contribute to high
blood cholesterol levels or cholesterol levels that are out of balance. Some of
these factors are within your control, and some are not.
To some extent, your genetic make-up
determines your cholesterol level.
· Some
people inherit a condition called familial hypercholesterolemia, which means
that very high cholesterol levels run in the family.
· Some
people may simply be more likely than others to react to lifestyle factors
(such as lack of exercise or a high-fat diet) that push up cholesterol levels.
· Other
people, especially people for whom diabetes runs in the family, inherit high
triglyceride levels. Triglycerides are another type of blood fat that can also
push up cholesterol levels.
Besides your genetic make-up, many
lifestyle factors affect cholesterol levels and cholesterol balance:
· What you eat. Eating too
much saturated fat (the kind found in high-fat meats and dairy products) and
cholesterol can cause your body to make more cholesterol, raising your blood
cholesterol levels. You can lower your cholesterol level by cutting down on
animal fat and other fats and eating foods rich in starch and fiber, such as
fresh fruits, vegetables, and whole grains.
· How active you
are.
Regular exercise not only reduces total blood cholesterol, but it lowers the
bad kind of cholesterol (LDL cholesterol) while raising the good kind of
cholesterol (HDL cholesterol).
· What you
weigh.
Being overweight contributes to rising blood cholesterol levels. Fortunately,
changes to lower cholesterol levels also help you control your weight, a double
benefit.
· Your hormones. Women get a
natural boost in their HDL cholesterol (the good kind of cholesterol) from
their hormones until they reach menopause. After menopause, taking estrogen can
help maintain higher HDL cholesterol levels.
Why
Worry About High Blood Cholesterol?
When we get more cholesterol than we
need - either because our body makes too much or because we eat too many
cholesterol-rich foods - the surplus cholesterol circulates in the bloodstream.
Along with other fat-like substances, certain kinds of this circulating
cholesterol tend to deposit in the inner lining of the blood vessels.
These cholesterol-rich deposits become
coated with scar tissue, forming a bump in the blood vessel known as plaque.
Plaque buildup can narrow and harden the blood vessel - a process called
atherosclerosis, or hardening of the arteries.
Eventually these plaque deposits can
build up to significantly reduce or block blood flow, causing a heart attack or
stroke. Many people experience chest pain or discomfort from inadequate blood
flow to the heart, especially during exercise when the heart needs more oxygen.
Smaller plaques can also burst, causing blood flowing over them to clot and
clog the blood vessel.
A high blood cholesterol level is
especially dangerous for smokers and those with high blood pressure. High blood
cholesterol, smoking, and high blood pressure are three factors that increase
your risk for heart disease.
·
If
you have one of these risk factors, you double your risk of heart disease.
·
If
you have two of these risk factors, your risk for heart disease is four times
as high.
·
If
you have three of these risk factors, your risk is eight times as high.
The good news is that lowering your
cholesterol level can help reduce your risk for heart disease. For everyone one
percent you lower your cholesterol level, you reduce your risk for heart
disease by two percent. And lowering your cholesterol can help prevent heart
attacks even if you already have heart disease.
Also Read: Is Your Blood CholesterolLevel Too High?
How
What You Eat Affects Your Cholesterol
How
Does Dietary Fat Affect Blood Cholesterol?
There are three main types of fats in
food, and they affect blood cholesterol in different ways:
· Saturated fat - Found in
red meats and red meat products, such as beef, pork, and lamb, as well as dairy
products; in tropical oils such as palm oil, palm kernel oil, and coconut oil;
and in vegetables oils that have been chemically changed to make them solid at
room temperature (a process called hydrogenation).
· Monounsaturated
fats
- Found in plant oils such as olive, canola, and peanut oil. Monounsaturated
fats are liquid at room temperature but harden in the refrigerator.
· Polyunsaturated
fats
- Found in plant oils such as safflower, sunflower, corn, or soybean oil. Fish,
especially cold-water fish, contain a special type of polyunsaturated fat
called omega-3 fat that may help protect against heart disease by slowing blood
clotting. Polyunsaturated fats remain liquid even at colder temperatures.
Which
Fats Raise Blood Cholesterol Levels?
Although all fats are concentrated
sources of calories and can contribute to weight gain (and thus, high blood
cholesterol levels), saturated fat is the most harmful type of fat.
Saturated fat is the main cause of
high blood cholesterol levels. When you eat too much saturated fat, your body
reacts by making more cholesterol than it needs, and the surplus ends up in
your blood.
Which
Fats Lower Blood Cholesterol Levels?
Both monounsaturated and
polyunsaturated fats help lower blood cholesterol levels by helping your body
get rid of newly-formed cholesterol. But these fats should replace some of the
saturated fat in your diet - not be used in addition to saturated fat.
However, all fats, even if they are
monounsaturated and polyunsaturated, are high in calories. Fat contains nine
calories per gram (a measure of weight). In comparison, protein and
carbohydrates only contain four calories per gram. Using a large amount of
monounsaturated or polyunsaturated fats to lower cholesterol will backfire,
because the extra calories will make you gain weight, which will push up your
cholesterol levels.
To replace saturated fat with
monounsaturated and polyunsaturated fat:
· Use
margarine and spreads made from these oils instead of butter. (If a food lists
a hydrogenated oil as the first or second ingredient, it is still high in
saturated fat.)
· Use
liquid vegetable oils in cooking.
· Use
non-stick vegetable oil spray to coat cooking pans.
· Read
the ingredient labels and choose foods made with vegetable oils rather than
hydrogenated vegetable oils, lard, butter, or tropical oils such as palm or
coconut oil.
How
Does Dietary Cholesterol Affect Blood Cholesterol?
Although a diet high in saturated fat
is the main cause of high blood cholesterol levels, high cholesterol in the
diet can also raise blood cholesterol levels. And usually the effect is twice
as bad, because foods high in cholesterol are usually high in saturated fat.
Which
Foods Contain Cholesterol?
Only animal foods contain cholesterol
- plant foods do not contain cholesterol. In animals, as in humans, cholesterol
is a part of all cells and serves many vital functions. Therefore, foods of
animal origin - such as meat, poultry, fish, eggs, or milk - all contain some
cholesterol.
Generally, foods high in animal fat
are also high in cholesterol. Two exceptions to this generalization are liver
and eggs, which are not high in fat but are high in cholesterol.
· Liver contains
large amounts of cholesterol because the liver is the body organ that makes
cholesterol.
· Eggs contain large
amounts of cholesterol because they contain the nutrients and other substances
to support a growing embryo (eggs also contain a very high quality of protein
and are rich in vitamins and minerals).
The table below shows the approximate
cholesterol content of some common animal-based foods.
|
Food
|
Milligrams of cholesterol
|
|
3 ounces of liver
|
300
|
|
one large egg
|
215
|
|
3 ounces of lean red meat
|
90
|
|
3 ounces skinless poultry
|
90
|
|
3 ounces fish
|
50
|
|
one cup whole milk
|
33
|
|
one ounce cheese
|
30
|
|
1 teaspoon butter
|
11
|
|
one cup skim milk
|
4
|
How
Much Cholesterol Is Too Much?
The American Heart Association and
other health experts recommend that you eat less than 300 milligrams of
cholesterol daily.
·
The
average American man eats about 360 milligrams of cholesterol daily.
·
The
average American woman eats about 240 milligrams of cholesterol daily.
What counts is your daily average over
time, not your exact total each day. If you eat scrambled eggs for breakfast on
Saturday but eat lean meats, poultry, and fish, along with liberal servings of
fruits, vegetables, and grains the rest of the week, your daily average is
likely to be below 300 milligrams.
How
Do Dietary Carbohydrates Affect Blood Cholesterol?
Carbohydrates come in two varieties -
simple and complex.
Simple carbohydrates include:
·
Refined
sugars such as table sugar, brown sugar, and corn syrup
·
Naturally
occurring sweeteners such as honey and sugars present in fruits and vegetables
Complex carbohydrates include:
·
Starches,
found in grain products and starchy vegetables such as potatoes and corn
·
Dietary
fiber, found in whole grain products, fruits, and vegetables
Foods rich in complex carbohydrates
include fruits, vegetables, breads, pasta, rice, cereals, dried beans and peas,
nuts, and seeds.
Experts recommend that we get 55% to
60% of our calories from carbohydrates - mostly complex carbohydrates. The
average American gets 40% to 50% of calories from carbohydrates and about 20%
of calories from sugars.
How
Can Eating Foods Rich In Starches And Dietary Fiber Help Lower Blood Cholesterol?
Eating more of the foods rich in
starches and dietary fiber - fruits, vegetables, whole grains, beans, nuts, and
seeds - can help lower your cholesterol level in several ways:
· Carbohydrate-rich
foods like fruits, vegetables, and whole grains are naturally low in calories.
When you eat more of these foods, you will eat less of the foods higher in fat
and cholesterol.
· Fruits,
vegetables, whole grains, beans, and nuts and seeds are good sources of dietary
fiber. Dietary fiber, especially a certain type of fiber called soluble fiber,
can help lower cholesterol levels by sweeping cholesterol out of the body
before it gets to the bloodstream. Especially high in soluble fiber are foods
such as oat bran, beans, peas, rice bran, citrus fruits, and psyllium seed (the
main ingredient in Metamucil, a fiber supplement available at pharmacies and
grocery stores).
·
Carbohydrate-rich
fruits and vegetables also contain vitamin E, vitamin C, beta-carotene and
other substances that function as antioxidants. Antioxidants help prevent
cholesterol from being moved out of the blood and into the lining of the blood
vessels.
Also Read:
What
Is The Best Way Lower Blood Cholesterol? (Full Article)
Reducing
Total Fat
Ounce for ounce, fat contains over
twice the calories that protein or carbohydrates do. So even if saturated fat
is the type of fat most likely to raise harmful blood cholesterol levels, you
should limit intake of all fats. Eating too much fat, no matter what kind, can
make you put on excess weight. Eating too much fat can also increase your risk
of certain types of cancer, such as breast or colon cancer.
To
limit total fat intake:
· Broil,
bake, boil, or roast foods rather than fry.
· Use
non-stick pans or coat pans with a thin layer of non-stick spray.
· Add
less fat to food during both cooking and eating. Some examples include using
jam instead of margarine on toast, a non-fat or low-fat salad dressing instead
of a high-fat dressing, lemon juice instead of butter on vegetables, or salsa
instead of sour cream on baked potatoes.
· Experiment
with butter substitutes, spices, and other flavorings as alternative to fat.
· Look
for low-fat alternatives to foods, such as a bagel instead of a doughnut,
pretzels instead of potato chips, or a round steak instead of a t-bone steak
· Try
new fat-free products like yogurt, cookies, or crackers.
· Read
labels, which offer excellent information to help you compare fat content of
prepared foods.
Reducing
Saturated Fat And Cholesterol
To reduce the fat and cholesterol
intake in your diet, start with changes that are relatively easy to make. For
example, many people find it easy to switch from 2% milk to 1% or skim milk.
Once you have adjusted to one change, pick another change to work on.
Here are some simple changes that will
help you greatly reduce saturated fat and cholesterol in your diet.
Egg
yolks:
· Eat
no more than three eggs yolks weekly.
· Eat
as many egg whites as you like - they contain no cholesterol.
Meats:
· Buy
lean meats such as fish, poultry, veal cutlet, pork tenderloin, or flank steak.
· Trim
as much fat off meat as possible.
· Broil,
barbecue, or roast meat on a rack rather than fry them. This allows some of the
fat to escape during cooking.
· Limit
the amount of hamburger you eat, and buy the leanest type available.
· Replace
high-fat prepared meats like sausage and luncheon meats with lower-fat meats
like lean turkey or chicken.
· Remove
the skin from chicken or turkey before you cook or eat it.
· Try
to eat fish twice weekly. Fish contains a type of fat called omega-3 fat that
may help prevent heart disease.
Dairy
products:
· Use
margarine instead of butter, choosing a margarine that has a liquid oil rather
than a hydrogenated oil listed as the first ingredient.
· Choose
a lower-fat milk. If you use whole milk, switch to 2%. If you use 2%, switch to
1% or skim milk. (All types of milks have the same amount of calcium and other
vitamins and minerals.)
· Use
non-fat or low-fat yogurt.
· Use
plain non-fat yogurt instead of sour cream.
· Cut
down on the amount of regular cheeses you eat. Look for lower-fat cheese that
contains less than 3 grams of fat per ounce.
· Sprinkle
a little Parmesan cheese on food to give it a cheesy taste. Parmesan cheese is
strong tasting, so a little goes a long way.
Tropical
oils and processed oils:
· Check
food labels to see what the main type of fat in the food is. Limit foods that
list palm oil, coconut oil, or a hydrogenated oil as one of the first type of
fats. (Food labels list ingredients in order from greatest to least by weight.)
· Be
suspicious of commercial baked goods such as doughnuts, sweet rolls, brownies,
and cookies, which are a major source of saturated fat.
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