Proteins:
Proteins are macromolecules made up of 20 different amino
acids. They are chemically composed of carbon, hydrogen, oxygen, and nitrogen
and occasionally sulfur and phosphorous. The polymer (or lots of amino acids
combined) is polypeptide.
Protein sources come in two types: incomplete sources and
complete sources. This is based on if it supplies all the essential amino acids
(ones our bodies cannot produce). Complete protein sources, or high quality
proteins, are meat, poultry, fish, eggs, milk, and cheese. Incomplete protein
sources are rice and beans. When eaten together, they provide all the essential
amino acids; therefore, they are complementary proteins.
Proteins have many functions. Overall, proteins are designed
to do cell work.
They...
-
build new tissues
-
maintain and replace damaged tissues
-
carry out regulating activities such as enzymes
and hormones
-
act as antibodies
-
help in other important activities such as
movement, transport of oxygen, etc.
Proteins are found in meats, poultry, fish, legumes, tofu,
eggs, nuts and seeds, dairy products, fruits, vegetables, and grains.
10-35% of your daily caloric intake should be proteins. For
a teenage girl, 46 grams a day is recommended. For a teenage boy, 52 grams a
day is recommended.
1 gram of protein is 4 calories.
- 1 cup of milk has 8 grams of protein
- A 3-ounce piece of meat has about 21 grams of protein
- 1 cup of dry beans has about 16 grams of protein
- An 8-ounce container of yogurt has about 11 grams of
protein
Fats:
Fats
are a large group of compounds that are soluble in organic solvents but
insoluble in water. Fats (otherwise known as triglycerides [polymers] or "fatty
acids"[monomers]) can be either solid or liquid at room temperature. The term
"oil" is usually used to refer to a fat that is liquid at room
temperature, while the word "fat" is use to refer to fats that are solid
at room temperature.
Fats are a very important substance for many forms of life
including humans (teenagers especially). Fats serve as both structural and
metabolic functions in the human body. The human body uses fat for
long-term storage of energy. When the energy stored in body fat is
needed, the fat is broken down by an enzyme called lipase that is made
in the pancreas. Also, fat provides linoleic acid, which is essential for growth, healthy skin, and metabolism. Fats help us to absorb vitamin A,D,E, and K.
The most common forms of fat that we consume are saturated
fats, unsaturated fats, and trans fats. Saturated fats are fats that are solid at room temperature. They raise levels of bad LDL cholesterol. Unsaturated fats come in two types; monounsaturated fats and polyunsaturated fats. Monounsaturated fats are liquid at room temperature and lowers LDL levels while maintaining HDL levels. Polyunsaturated fats are liquid at room temperature, but too much can lower HDL levels. Trans fats are generally
considered "bad" because they have been shown to increase the risk of
heart disease. Although trans fats enhance the flavor of food, they have been processed (partial hydrogenation) so they get rid of good HDL cholesterol and raise bad LDL levels (see post Foods to Avoid).They should be avoided.
Another type of fat is Omega-3 fatty acids. This is critical for our health, but it cannot be created by our bodies. This fat reduced the risk of heart disease and boosts our immune systems.
Sources of trans fat are
- Processed foods, cookies, cakes, fries, and donuts
Sources of saturated fats are
- Animal products such as meat, dairy, and eggs
- Coconut, palm, and palm kernel oils
Sources of monounsaturated fats are
- Olives, olive oils, nuts, peanut oils, canola oils, and avocados
Sources of polyunsaturated fats are
- Safflower, sesame, corn, cottonseed, and soybean oils
Sources of Omega-3 fatty acids are
- Cold-water fish, flax seed, soy, and walnuts
Some people today have come under the impression that all fat is really bad
and should be avoided. This is not true. It is just as important to
have fat in your diet, as it is to have protein or any other nutrient.
It is recommended that you get 20-30% of your total calorie intake from
fat (or 400-600 calories in a 2000-calorie diet). 1 gram of fat is 9 calories.
Carbohydrates:
Carbohydrates are one
major macronutrient. There are three types of carbohydrates, simple, fibrous, and
complex. Simple carbohydrates (chemically made of one or two sugars) are also called simple sugars and are found
in refined sugars. Refined sugar is sugar that goes through a process
called refining. In this process, the sucrose is extracted from the raw
sugar and the other unwanted chemicals found in the sugar are discarded.
Of refined sugars the most common are granulated sugar and powdered
sugar. Many see these sugars as being bad for your body because they are
simply empty calories, not having any nutrients or minerals, and because of the
amount of nutrients it takes to actually takes to digest the sugar.
"Good" simple carbohydrates are also found in fruits, milk, and vegetables. Your body can use these sugars directly, and they don't have refined sugar in them.
Complex
carbohydrates are also called starches (made of three or more sugars). Good sources of starches are
grains such as bread, rice, and pasta. Like simple sugars, complex sugars
can also be refined. You know grains have been refined if they are white
like white bread, or white rice. If grains are refined, they lose their
nutrients and fiber. The fiber in unrefined complex carbohydrates are
important because it helps your digestive system and makes you feel full so you
are less likely to overeat.
Fibrous carbohydrates are complex carbohydrates that come from green leafy vegetables such as broccoli, peppers, and carrots. True to their name, they have lots of fiber in them. They help the digestive system to run smoothly. They also help to prevent colon cancer and gastrointestinal diseases.
Your body uses carbohydrates by breaking them down into simple sugars and
absorbing them into the bloodstream. When the sugar level in your blood
increases, your body releases insulin which moves the sugar from your blood
into your cells as a source of energy.
Carbohydrates...
- Provide most of the energy we use
- Important for the correct functioning of our brain, heart, nervous, digestive, and immune systems
It is recommended that you consume 300 grams of carbohydrates a day on a 2000
calorie diet. 300 grams of carbs is equal to 1200 calories, so you are
supposed to get 60% of your daily recommended calories from carbohydrates. 1 gram of carbohydrates is 4 calories.
Post on Proteins by Anna
Post on Fats by Brandon
Post on Carbohydrates by Kylie
Sources:
http://www.tutorvista.com/content/biology/biology-iv/animal-nutrition/proteins.php
http://www.cdc.gov/nutrition/everyone/basics/protein.html
http://dietsindetails.com/userfiles/protein.jpg
http://lowfatcooking.about.com/od/healthandfitness/p/trnasfats.htm
http://lowfatcooking.about.com/od/lowfatbasics/a/fats1004.htm
http://publications.usa.gov/epublications/reveal-fats/qatra2ch.gif
http://publications.usa.gov/epublications/reveal-fats/qatra2ch.gif
Michel
Bassford
http://www.nlm.nih.gov/medlineplus/ency/article/002468.htm
http://www.helpguide.org/life/healthy_diet_fats.htm
http://diabetes.about.com/od/carbohydratefaq/f/typesofcarbs.htm
http://www.briancalkins.com/simplevscomplexcarb.htm
