Download File - the Science of Food

Understanding Carbohydrates
Every few years, carbohydrates are vilified as public enemy
number one and are accused of being the root of obesity,
diabetes, heart disease and more. Carb-bashers shun yogurt
and fruit and fill up on bun-less cheeseburgers. Instead of
beans, they eat bacon. They dine on the tops of pizza and toss
the crusts into the trash. They so vehemently avoid carbs and
spout off a list of their evils that they may have you fearing
your food. Rest assured, you can and should eat
carbohydrates. In fact, much of the world relies on
carbohydrates as their major source of energy. Rice, for
instance, is a staple in Southeast Asia. The carbohydrate-rich
potato was so important to the people of Ireland that when the
blight devastated the potato crop in the mid 1800s, much of
the population was wiped out.
What are Carbohydrates?
The basic structure of carbohydrates is a sugar molecule, and they are classified by how
many sugar molecules they contain.

Simple carbs: Simple carbohydrates, usually referred to as sugars, are
naturally present in fruit, milk and other unprocessed foods. Plant carbohydrates can be
refined into table sugar and syrups, which are then added to foods such as sodas,
desserts, sweetened yogurts and more. Simple
carbohydrates may be single sugar molecules
called monosaccharides or two
monosaccharides joined together called
disaccharides. Glucose, amonosaccharide, is
the most abundant sugar molecule and is the
preferred energy source for the brain. It is a
part of all disaccharides and the only
component of polysaccharides. Fructose is
another common monosaccharide. Two
common disaccharides in food are sucrose,
common table sugar, and lactose, the source of frequent gas and bloating that some
experience from drinking milk.

Complex carbs: Complex carbohydrates are any that contain more than two
sugar molecules. Short chains are called oligosaccharides. Chains of more than ten
monosaccharides linked together are called polysaccharides. They may be hundreds
and even thousands of glucose molecules long. The way glucose molecules link together
makes them digestible (starch) or non-digestible (fiber). Polysaccharides include the
following.
o
o
o
Starch is a series of long chains of bound glucose molecules. It’s the
storage form of glucose for grains, tubers and legumes and is used during the plant’s
growth and reproduction.
Fiber is also long chains of glucose molecules, but they are bound in a
way we cannot digest.
Glycogen is the storage form of glucose in humans and other animals. It’s
not a dietary source of carbohydrate because it is quickly broken down after an animal
is slaughtered.
Carbohydrates in the Body
Whether they’re from a doughy bagel, a sugary cola or a
fiber-rich apple, carbohydrates’ primary job is to provide
your body with energy. From each of these sources and
others, carbohydrates provide you with 4 kcals/gram.

Carbs are fuel. Glucose is the primary fuel for
most of your cells and is the preferred energy for the brain
and nervous system, the red blood cells and the placenta
and fetus. Once glucose enters the cell, a series of
metabolic reactions convert it to carbon dioxide, water and
ATP (Adenosine Tri-Phosphate), the energy currency of the
cell. If you have more available glucose than your body
needs for energy, you will store glucose as glycogen (glycogenesis) in your liver and
skeletal muscle. When your blood glucose drops, as it does when you’re sleeping or
fasting, the liver will break down glycogen (glycogenolysis) and release glucose into
your blood. Muscle glycogen fuels your activity. The body can store just a limited
amount of glucose, so when the glycogen stores are full, extra glucose is stored as fat
and can be used as energy when needed.

Carbs spare protein. If you go without eating for an extended period or simply
consume too little carbohydrate, your glycogen stores will quickly deplete. Your body
will grab protein from your diet (if available), skeletal muscles and organs and convert
its amino acids into glucose (gluconeogenesis) for energy and to maintain normal blood
glucose levels. This can cause muscle loss, problems with immunity and other functions
of proteins in the body. That’s how critical it is to maintain normal blood glucose levels
to feed parts of your body and your brain.

Carbs prevent ketosis. Even when fat is used for fuel, the cells need a bit of
carbohydrate to completely break it down. Otherwise, the liver produces ketone bodies,
which can eventually build up to unsafe levels in the blood causing a condition called
ketosis. If you ever noticed the smell of acetone or nail polish remover on the breath of
a low-carb dieter, you have smelled the effects of ketosis. Ketosis can also cause the
blood to become too acidic and the body to become dehydrated.
Carbohydrates in the Diet
Carbohydrates, protein and fats are macronutrients, meaning the body requires them in
relatively large amounts for normal functioning. The Recommended Dietary Allowance
(RDA) for carbohydrates for children and adults is 130 grams and is based on the
average minimum amount of glucose used by the brain.[1] The Acceptable
Macronutrient Distribution Range (AMDR) for carbohydrates is 45–65%. If, for instance,
you ate 1600 kcals per day, the acceptable carbohydrate intake ranges from 180 grams
to 260 grams.
Most American adults consume about half of their calories as carbohydrates. This falls
within the AMDR, but unfortunately most Americans do not choose their carbohydratecontaining foods wisely. Many people label complex carbs as good and sugars as bad,
but the carbohydrate story is much more complex than
that. Both types yield glucose through digestion or
metabolism; both work to maintain your blood glucose;
both provide the same number of calories; and both
protect your body from protein breakdown and ketosis.
The nutrient-density of our food choices is far more
critical. For example, fresh cherries provide ample sugars,
and saltine crackers provide just complex carbs. Few
would argue that highly processed crackers are more
nutritious than fresh cherries.

Added Sugars: Americans eat only 42% of the recommended amount of fruit
and 59% of the recommended vegetable amount. We eat only 15% of the
recommended servings of whole grains, but 200% of the recommended servings of
refined grains.[2] Americans over-consume added-sugars, which make up 16% of the
total calories in the American diet. Nearly 60% of added sugars come from soda,
energy drinks, sports drinks, fruit drinks and grain-based desserts like cakes, cookies
and brownies.[3] The problem with added sugars is that they do not come packaged
with an abundance of nutrients like a piece of fruit and a glass of milk do. For this
reason, many people call them empty calories.

Glycemic Index: Sometimes people look to the
glycemic index (GI) to evaluate the healthfulness of
carbohydrate-rich foods, but this too oversimplifies good
nutrition. The GI ranks carbohydrate-containing foods from
0 to 100. This score indicates the increase in blood glucose
from a single food containing 50 grams of carbohydrate
compared to 50 grams of pure glucose, which has a GI
score of 100. Foods that are slowly digested and absorbed
- like apples and some bran cereals - trickle glucose into
your bloodstream and have low GI scores. High GI foods
like white bread and cornflakes are quickly digested and
absorbed, flooding the blood with glucose. Research
regarding the GI is mixed; some studies suggest that diets
based on low GI foods are linked to lower risks of diabetes,
obesity and heart disease, but other studies fail to show
such a link.
Many factors influence a food’s GI score, including:
The degree of ripeness of a piece of fruit (the riper the fruit, the higher
o
the score)
o
o
o
The amount and type of processing a food has undergone
Whether the food is eaten raw or cooked
The presence of fat, vinegar or other acids
All of these factors complicate the usefulness of the GI. Additionally, many high-calorie,
low-nutrient foods such as some candy bars and ice creams have desirable GI scores,
while more nutritious foods like dates and baked potatoes have high scores. It’s
important to recognize that the healthfulness of a food depends largely on its nutrient
density, not its type of carbohydrate or its GI score.
Proponents of low-carbohydrate diets are incensed by the RDA and AMDR for
carbohydrates. “Nutrition experts are trying to kill us,” they argue and claim that
carbohydrates have made us overweight. However, research supports that diets of a
wide range of macronutrient proportions facilitate a healthy weight, allow weight loss
and prevent weight regain. The critical factor is reducing the calorie content of the diet
long-term.[4][5]

Fiber Needs: If we shunned all carbohydrates or if we severely restricted them,
we would not be able to meet our fiber needs or get ample phytochemicals, naturally
occurring compounds that protect the plant from infection and us from chronic disease.
The hues, aromas and flavors of the plant suggest that it contains phytochemicals.
Scientists have learned of thousands of them with names like lycopene, lutein and
indole-3-carbinol. Among other things, phytochemicals appear to stimulate the immune
system, slow the rate at which cancer cells grow, and prevent damage to DNA.
All naturally fiber-rich foods are also rich in carbohydrates. The recommended intake for
fiber is 38 grams per day for men and 25 grams per day for women. The usual fiber
intake among Americans, however, is woefully lacking at only 15 grams daily. Perhaps
best known for its role in keeping the bowels regular, dietary fiber has more to brag
about. Individuals with high fiber intakes appear to have lower risks of coronary heart
disease, stroke, hypertension, diabetes and obesity.[6] Fiber-rich foods are protective
against colorectal cancer[7], and increasing fiber intakes improves gastroesophageal
reflux disease and hemorrhoids.[6] Some fibers also lower blood cholesterol and glucose
levels. Additionally, fibers are food for the normal (healthy) bacteria that reside in your
gut and provide nutrients and other health benefits. To
boost your fiber intake, eat fruits, vegetables, whole grains
and beans frequently.
Fiber Content of Selected Foods

Beans (navy, pinto, black, lima etc), 1/2 cup: 6.2 –
9.6 g

100% Bran cereal, 1/3 cup: 9.1 g

Pear, medium: 5.5 g

Whole-wheat English muffin, 1: 4.4 g

Raspberries, 1/2 cup: 4.0 g

Sweet potato with skin, medium: 3.8 g

Apple with skin, 1 medium: 3.6 g

Orange, medium: 3.1 g

Potato with skin, 1 medium: 3.0 g

Broccoli, cooked, 1/2 cup: 2.6 – 2.8 g
Source: Dietary Guidelines for Americans, 2011 (Appendix
13)
Carbohydrates are critical sources of energy for several body systems. Nourish your
body and help shield yourself from chronic disease by getting most of your
carbohydrates from fruits, whole grains, legumes, milk and yogurt. Limit added sugars
and heavily processed grains.
Source: http://www.innerbody.com/nutrition/macronutrients
Understanding Proteins
What’s for dinner? In the U.S, this question is
usually answered with some type of meat like
pot roast, chicken, salmon or meatloaf. Meat,
because it’s rich in protein, is usually central
to the meal, and vegetables and grains are
frequently the afterthought. This may give the
impression that a meal isn’t complete without
meat and that we need lots of meat or protein
for good health. The truth is, most Americans
eat much more protein than their bodies
require. And even if you choose to eat no
meat at all, you can still meet your protein needs.
Proteins in the Body
Like carbohydrates and lipids, proteins are one of the macronutrients. Though protein
provides your body with 4 kcals per gram, giving you energy is not its primary role.
Rather, it’s got way too many other things going on. In fact, your body contains
thousands of different proteins, each with a unique function. Their building blocks are
nitrogen-containing molecules called amino acids. If your cells have all 20 amino acids
available in ample amounts, you can make an infinite number of proteins. Nine of those
20 amino acids are essential, meaning you must get them in the diet.

Some proteins are enzymes. Enzymes speed up chemical actions such as the
digestion of carbohydrates or the synthesis of cholesterol by the liver. They increase
the rate of chemical reactions so much that not having them because of a genetic
defect can be catastrophic.

Some proteins are hormones. Hormones are chemicals that are created in
one part of the body and carry messages to another organ or part of the body. For
example, both glucagon and insulin are hormones that are made in the pancreas and
travel throughout the body to regulate blood glucose.



Some proteins provide
structure.The protein collagen gives structure
to bones, teeth and skin. Hair and nails
depend on keratin.
Some proteins are
antibodies.Without adequate protein, your
immune system cannot properly defend you
against bacteria, viruses and other invaders.
Antibodies are the blood proteins that attack and neutralize these invaders.

Proteins maintain fluid balance.Fluid is present in many compartments of
your body. It is within the cells (intracellular fluid), in the blood (intravascular fluid) and
between the cells (interstitial fluid). Fluids also flow between these spaces. It’s the
proteins and minerals that keep them in balance. Proteins are too large to pass freely
across the membranes separating the compartments, but since proteins attract water,
they act to maintain proper fluid balance. If your protein intake is too low to maintain
normal blood protein levels, fluid will leak into the surrounding tissues and cause
swelling called edema.

Proteins transport nutrients and other compounds. Some proteins sit
inside your cell membranes pumping compounds in and out of the cell. Others attach
themselves to nutrients or other molecules to transport them to distant parts of the
body. Hemoglobin, which carries oxygen, is one such protein.

Proteins maintain acid-base balance. Blood that is too acidic or too alkaline
will kill you. Fortunately, the body regulates its acid-base balance very tightly. One
mechanism uses proteins as buffers. Proteins have negative charges that pick up
positively charged hydrogen ions when conditions are too acidic. Hydrogen ions can
then be released when the blood is too alkaline. To illustrate the dire consequences of
an acid-base imbalance, think about what happens to proteins in an environment too
acid or alkaline. They get denatured which changes their shape and renders them
useless. Hemoglobin, for example, would not be able to carry oxygen throughout your
body.

Protein is a back up source of energy. With so many jobs, you can see why
protein is not used as a primary source of energy. But rather than allowing your brain
to go without glucose in times of starvation or low carbohydrate intake, the body
sacrifices protein from your muscles and other tissues or takes it from the diet (if
available) in order to make new glucose from amino acids in a process called
gluconeogenesis.
Proteins in the Diet
Bodybuilders drink protein shakes for
breakfast and after working out. Dieters with
no time to stop for lunch grab protein bars.
Are these strategies necessary for optimal
strength building and weight loss? Probably
not.
Proteins in the body are constantly broken
down and re-synthesized. Our bodies reuse
most of the released amino acids, but a small
portion is lost and must be replaced in the
diet. The requirement for protein reflects this lost amount of amino acids plus any
increased needs from growth or illness. The Recommended Dietary Allowance (RDA) for
protein for adults is 0.8 g/kg of body weight. Because of their rapid growth, infants
have the highest RDA for protein at 1.5 g/kg of body weight. The RDA gradually
decreases until adulthood. It increases again during pregnancy and lactation to a level
of 1.1 g/kg. The RDA for an adult weighing 140 pounds (63.6 kg) is a mere 51 grams of
protein, an amount many of us consume before mid-afternoon.

Physical Activity. The RDA remains the same regardless of physical activity
level. There is some data, however, suggesting that both endurance and strength
athletes have increased protein needs compared to inactive individuals. Endurance
athletes may need as much as 1.4 g/kg, and strength athletes may require as much as
1.7 g/kg.[8] A bodybuilder weighing 200 pounds (90.9 kg) may then need as much as
155 grams protein.

Age. The Acceptable Macronutrient Distribution Range (AMDR) for protein for
men and women age 19 and older is 10–35% of total calories. For children age 4 and
over, it is 10–30%, and for younger children, the range is 5–20%. For an adult
consuming 1600 kcals per day, the acceptable protein intake ranges from 40–140
grams per day, an amount easily met. Consider the 200-pound bodybuilder whose
protein needs are approximately 155 grams per
day. With energy needs approximately 4500
kcals per day, his protein needs are only 14% of
his total calories—well within the AMDR. With his
energy needs so great, however, his diet will
need careful planning. If he requires engineered
foods such as bars and shakes, it will most likely
be to meet his energy needs rather than his
protein needs.
One population that needs special attention is
the elderly. Though the RDA for older adults
remains the same as for younger adults, some research suggests their needs may be
1.2 grams/kg body weight in order to prevent the common muscle loss and
osteoporosis that come along with aging.[9] Though this doesn’t require the elderly to
eat large servings of food, they frequently have poor appetites and dental problems
that make chewing difficult. Helping them meet their nutritional needs may take a little
creativity and perseverance.

Vegetarian Diets. People become vegetarian for a variety of reasons including
religious beliefs, health concerns, and a concern for animals or for the environment.
Oftentimes, “How can I get my protein?” is the first question asked when people discuss
their choice for vegetarianism. Yes, in the typical American diet, most of our protein
comes from animal foods. It is possible, however, to meet all of your protein needs
while consuming a vegetarian diet. You can even eat adequate protein on a carefully
planned vegan diet - a diet that excludes all animal products, including eggs and dairy.
When you think of protein, like most people, you probably think of beef, chicken,
turkey, fish and dairy products. Beans and nuts might come to mind as well. Most foods
contain at least a little protein, so by eating a diet with variety, vegetarians and vegans
can eat all the protein they need without special supplements.
This list illustrates the amount of protein found in common foods that may be included
in your diet.
Approximate Protein Content of Selected Foods

Poultry, beef, fish, 4 ounce: 28g

Broccoli, 1 cup cooked: 6g

Milk, 8-fluid ounce: 8g

Peanut butter, 2 Tbsp: 8g

Kidney beans, 1 cup: 13g

Whole-wheat bread, 1 slice: 4g

A complete protein includes all of the essential
amino acids. Complete proteins include all
animal proteins and soy. Incomplete proteins
lack one or more essential amino acids.
Beans, nuts, grains and vegetables are incomplete proteins. Previously, registered
dietitians and physicians advised vegetarians to combine foods that contained
incomplete proteins at the same meal to give the body all the necessary amino acids it
needed at one time. Today we know this is unnecessary. Your body combines
complementary or incomplete proteins that are eaten in the same day.[10]
If you eat a variety of foods, you will meet your protein needs. Recreational athletes
rarely need protein supplements. Professional athletes should consult a registered
dietitian (RD) who is also a Certified Specialist in Sports Dietetics (CSSD). If you are
vegetarian or vegan, it’s wise to see a registered dietitian for careful planning of your
diet to meet not just your protein needs, but other nutrients as well.
Source: http://www.innerbody.com/nutrition/macronutrients
Understanding Fats
It all started in the ‘80s. Doctors, nutritionists
and public health officials told us to stop
eating so much fat. Cut back on fat, they said,
to lose weight and fend off heart disease
among other ills. Americans listened, but that
didn’t improve our food choices. Rather, lowfat food labels seduced us, and we made
pretzels and fat-free, sugar-rich desserts our
grocery staples. Today we know to focus on
the quality of the fat instead of simply the
quantity.
Fats in the Body
Say NO to very low-fat diets. Why? Many people find them limiting, boring, tasteless
and hard to stick to. And because fat tends to slow down digestion, many low-fat
dieters fight hunger pangs all day or eat such an abundance of low-fat foods that their
calorie intake is too great for weight loss.
Dietary fat has critical roles in the body. Each gram of fat, whether it’s from a spoon of
peanut butter or a stick of butter, provides 9 kcals. This caloric density is a lifesaver
when food is scarce and is important for anyone unable to consume large amounts of
food. The elderly, the sick and others with very poor appetites benefit from high-fat
foods. Because their tiny tummies can’t hold big volumes, small children too need fat to
provide enough calories for growth.

Fats are an energy reserve. Your body can store
just small amounts of glucose as glycogen for energy, but
you can put away unlimited amounts of energy as fat
tissue. This is a problem in our world of excess calories,
but was necessary in earlier times when food was scarce.
You’ll use this stored energy while you’re sleeping, during
periods of low energy intake and during physical activity.
Fats provide essential fatty acids (EFA). Fatty
acids differ chemically by the length of their carbon chains,
the degree of saturation (how many hydrogen atoms are
bound to carbon) and the location of carbon-carbon double bonds. These are critical
differences that give each fatty acid unique functions.

Our bodies are amazing machines capable of producing most of the needed fatty acids.
There are two fatty acids that it cannot make at all, however. They are called LA
(linoleic acid) and ALA (alpha linolenic acid). This makes LA and ALA "essential",
meaning they must be obtained through the diet. In the body, fatty acids are important
constituents of cell membranes, and they are converted to chemical regulators that
affect inflammation, blood clotting, blood vessel dilation and more. Clinical deficiencies
are rare. A deficiency of LA is usually seen in people with severe malabsorption
problems. Its symptoms are poor growth in children, decreased immune function, and a
dry, scaly rash. In the few cases of ALA deficiency that doctors and researchers are
aware of, the symptoms were visual problems and nerve abnormalities.

Fats carry fat-soluble nutrients. Dietary fats dissolve and transport fatsoluble nutrients, such as some vitamins and also disease-fighting phytochemicals like
the carotenoids alpha- and beta-carotene and lycopene. To illustrate, researchers were
able to detect only negligible amounts of absorbed carotenoids in the blood of
individuals who had eaten a tossed salad with fat-free salad dressing. With reduced-fat
dressing, the study participants absorbed some carotenoids, but with full-fat dressing,
they absorbed even more.[11]

Fats add to the texture and flavor of foods. You already know that fat makes
food taste good. That’s partly because fats dissolve flavorful, volatile chemicals. They
also add a rich, creamy texture, giving food a satisfying mouthfeel. Imagine the texture
of fat-free chocolate. Not good, probably. Finally, fats provide a tenderness and
moistness to baked goods.
Fats in the Diet
Fats and oils (collectively known as lipids) contain mixtures
of fatty acids. You may refer to olive oil as a
monounsaturated fat. Many people do. Really, however,
olive oil contains a combination of monounsaturated,
saturated and polyunsaturated fatty acids, but it has more
monounsaturated fatty acids than other types. Similarly, it
is technically incorrect to call lard a saturated fat. It does
contain mostly saturated fatty acids, but both
monounsaturated and polyunsaturated fatty acids are
present as well.
There is no Recommended Dietary Allowance (RDA) or
Adequate Intake (AI) for total fat intake for any population
other than infants. Depending on the age, the AI for
infants is 30 or 31 grams of fat per day. The Acceptable
Macronutrient Distribution Range (AMDR) is 20–35% for
men and women age 19 years and older. For an adult consuming 1600 kcals then, the
acceptable fat intake ranges from 35 to 62 grams daily. The AMDR for children is higher
and varies by age, starting out at 30–40% for children ages 1 to 3 and gradually
approaching the AMDR for adults. Experts discourage low-fat diets for infants, toddlers
and young children because fat is energy-dense, making it appropriate for small, finicky
appetites and to support growth and the developing central nervous system. The AIs for
LA and ALA for adults range from 11–17 grams and 1.1 to 1.6 grams, respectively.

Saturated Fats. Because your body can make all the saturated fatty acids it
needs, you do not need any in the diet. High intakes of most saturated fatty acids are
linked to high levels of LDL (low-density lipoprotein), or bad, cholesterol and reduced
insulin sensitivity.[12] According to the Dietary Guidelines for Americans 2010, we
should limit our intake of saturated fatty acids to 10% of our total calorie intake (18
grams for someone eating 1600 kcals daily) to reduce LDL cholesterol and our risk for
heart disease. The American Heart Association favors a greater restriction to just 7% of
total calories (12 grams for a 1600 kcal diet). If you tried to eat no saturated fatty
acids, however, you would soon find that you
had little to eat. Remember that fats are
combinations of fatty acids, so even nuts and
salmon (good sources of healthy fats) contain
some saturated fatty acids.
What does bacon grease look like after the
pan has cooled? Its firmness is a hint that
bacon is high in saturated fat. Many saturated
fats are solid at room temperature. Dairy fat
and the tropical oils (coconut, palm and palm
kernel) are also largely saturated. The
greatest sources of saturated fat in the American diet are full-fat cheese, pizza and
desserts.[13]
The benefit you experience from reducing your intake of saturated fats depends on
many factors, including what you replace them with. Loading up on fat-free pretzels
and gummy candies may be tempting, but is a misguided strategy because diets high in
heavily refined carbohydrates typically increase triglycerides and lower the beneficial
HDL (high-density lipoprotein) cholesterol, both risk factors for heart disease. A better
strategy is to replace the foods rich in unhealthy fats with foods rich in healthy fats.
Cooking with oils is better than cooking with butter or lard. A quick lunch of a peanut
butter sandwich instead of a slice of pizza will do your heart some good. Trading out
some of the cheese on your sandwich for a slice or two of avocado is another smart
move. If your calories are in excess, switch from whole milk or 2% reduced-fat milk to
1% low-fat milk or nonfat milk to trim both calories and saturated fats.

Trans Fats. Food manufacturers create both saturated and trans fats when they
harden oil in a process called hydrogenation, usually to increase the shelf life of
processed foods like crackers, chips and cookies. Partial hydrogenation converts some,
but not all, unsaturated fatty acids to saturated ones. Others remain unsaturated but
are changed in chemical structure. These are the health-damaging trans fats.
Many experts consider trans fats even worse than saturated fats because, like saturated
fats, they contribute to insulin resistance[14] and raise LDL cholesterol, but there's more
bad news. They also lower HDL cholesterol (the good cholesterol).[15] The American
Heart Association recommends that we keep our trans fatty acid intake to less than 1%
of total calories (less than 2 grams if consuming 1600 calories daily). Achieving this
might be trickier than you realize because many foods touting No Trans Fats on their
labels actually contain traces of these artery-scarring fats. That’s because the law
allows manufacturers’ to claim zero trans fats as long as a single serving contains no
more than 0.49 grams. If you eat a few servings of foods with smidgens of trans fat like
margarine crackers and baked goods, you can
easily exceed the recommended limit.
Identify traces of trans fats by reading the
ingredients lists on food labels. Partially
hydrogenated oil is code for trans fat. You
know that there are at least traces of trans fat
present. When oil is fully hydrogenated (the
label will say hydrogenated or fully
hydrogenated), it will not contain trans fats.
Instead, the unsaturated fatty acids have been

o
o
converted to saturated fatty acids.
Unsaturated Fats. As discussed, unsaturated fatty acids improve blood
cholesterol levels and insulin sensitivity when they replace saturated and trans fats.
There are two classes of unsaturated fatty acids: monounsaturated fats and
polyunsaturated fats.
Monounsaturated fat souces include avocados, nuts, seeds and olives. Peanut, canola
and olive oils are additional sources.
There are several types of polyunsaturated fats, and they each have different roles in
the body.
Omega-3 fatty acids have been in the spotlight recently because of their
role in heart disease prevention. ALA is an omega-3 fatty acid, and you can find it in
walnuts, ground flaxseed, tofu and soybeans, as well as common cooking oils like
canola, soybean and walnut oils. Remember that your body is unable to create ALA, so
it’s essential to get it in the diet. From ALA, your body makes two other critically
important omega-3 fatty acids (EPA and DHA), but the conversion is very inefficient.
It’s better to get EPA and DHA from fish. Not only are EPA and DHA important to the
heart, but they also promote visual acuity and brain development in the fetus, infant
and child; they seem to slow the rate of cognitive decline in the elderly; and they may
decrease the symptoms associated with arthritis, ulcerative colitis and other
inflammatory diseases. You will find them in bluefish, herring, lake trout, mackerel,
salmon, sardines, and tuna.
Omega-6 fatty acids are a second type of polyunsaturated fats. LA is an
omega-6 fatty acid and has to be acquired through the diet. Sources of omega-6 fatty
acids are sunflower seeds, Brazil nuts, pecans and pine nuts. Some cooking oils are
good sources too, such as corn, sunflower, safflower and sesame oils.[16]
When you work on reducing whole-milk dairy, solid fats (like butter and bacon grease),
and processed foods containing partially hydrogenated oils, be sure to replace them
with unsaturated fats rather than simply adding extra calories to your usual diet.
Otherwise you can expect to loosen your belt as you put on the pounds.
Don’t fear fats. Instead choose them wisely, making sure you do not exceed your
calorie needs. Enjoy foods with monounsaturated and polyunsaturated fats while
limiting the saturated and trans fats.
Source: http://www.innerbody.com/nutrition/macronutrients