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Nutrition Notes
Food (nutrients) fulfills three basic needs:1) It provides energy 2) It supports new
tissue growth and tissue repair 3) It helps to regulate metabolism. There are six major
classifications of nutrients: carbohydrates, fats, proteins, vitamins, minerals, and water.
There are over 40 nutrients in food that the body needs for growth, maintenance, energy,
and repair and must be obtained from the foods we eat. No one food contains all of these
essential nutrients, so it is important to eat a variety of foods. There are 10 leader
nutrients: fat, carbohydrates, protein, vitamin A, vitamin C, thiamin (vitamin B1),
riboflavin (vitamin B2), niacin, iron, and calcium. If a person gets these 10 leader
nutrients, then the other 30 typically will "follow." Paying attention to getting the leader
nutrients is important to avoiding possible nutrient deficiencies. Nutritional deficiencies
can result in serious illness so The Food and Nutrition Board of the National Research
Council and the National Academy of Sciences have worked together to establish
guidelines concerning the quantities of the various nutrients required to meet the minimal
nutritional needs of most health individuals. The guidelines are known as the
Recommended Dietary Allowances (RDA) and are designed to provide benchmarks that
represent the minimum level of intake of essential nutrients.
The Dietary Guidelines
The Department of Health and Human Services (HHS) and the Department of
Agriculture (USDA) have published the Dietary Guidelines for Americans jointly every 5
years since 1980. The Guidelines provide authoritative advice for people two years and
older about how good dietary habits can promote health and reduce risk for major chronic
diseases. Below is a summary of some of the Dietary Guidelines for Americans. For a
more extensive review of the guidelines you can go to
http://www.health.gov/dietaryguidelines/dga2005/document/default.htm.
Dietary Guidelines for Americans:

Eat a variety of foods. As stated in the previous concept, humans need more than
40 different essential nutrients to stay healthy. No single food provides all the
essential nutrients so the best way to obtain these nutrients is to eat a variety of
foods from the basic food groups.
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
Maintain a desirable weight. Obesity and excess weight increase medical
problems and, in many cases, premature death.

Avoid too much fat, saturated fat, and cholesterol. Diets with excessive fat and
cholesterol have been shown to increase obesity, which in turn increase the risk
for developing high blood pressure, increases the risk of stroke, increases the
likelihood of non-insulin-dependent diabetes, and increases the risk for certain
cancers, including cancer of the breast, colon, and uterus.

Eat foods containing adequate starch and fiber. Starch and fiber belong to the
carbohydrate food group Adequate intake of each helps prevent constipation,
reduces the chances of colon cancer, and lowers the cholesterol levels.

Avoid too much sugar. Diets high in sugar are linked with obesity, malnutrition,
and tooth decay.

Avoid too much salt. The major health concern associated with too much salt is
hypertension.

If you drink alcoholic beverages, do so in moderation. Excessive use of alcohol is
associated with liver disease, some types of cancer, high blood pressure, stroke,
and disorders of the heart muscle.
Carbohydrates
Carbohydrates are the major source of calories used by the body and provide the
most efficient source of energy for work, cell maintenance, and heat. Each gram of
carbohydrates is metabolized more quickly and efficiently than proteins and fat, so they
are the energy source used first in high-intensity activities. Each gram of carbohydrates
has 4 calories.
The basic structural unit of all carbohydrates is simple sugar. During digestion
and metabolism, carbohydrates are broken down and converted to glucose, the body’s
primary source of energy. Any glucose not needed immediately is stored as glycogen in
muscle and liver cells to be released as needed. Unfortunately, only a limited amount of
glucose can be stored as glycogen; anything left over is converted to fat and stored within
the body. Since carbohydrates are broken down more quickly than fats or proteins, a
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person is more likely to get hungrier faster eating only carbohydrates, and they can also
be stored as fat faster than proteins or fats.
There are two major types of carbohydrates: simple (sugar) and complex (starch).
Simple carbohydrates have little nutritional value and are denoted as sugar (candy,
soda, & cake). Complex carbohydrates contain many valuable nutrients and provide an
excellent source of fiber and roughage. Complex carbohydrates are found in grains,
cereals, fruits and vegetables, and potatoes, and are formed when three or more simple
sugar molecules link together. Simple carbohydrates often take the place of more
nutritional foods in the diet, as such, most Americans do not get enough complex
carbohydrates in their daily diets.
Fiber
Fiber is a type of complex carbohydrate made up of the indigestible portion of
plant material and is referred to as bulk or roughage. The main sources of fiber include
whole grain cereal and breads, fruits, and vegetables. Since humans cannot digest fiber,
it provides bulk in the intestinal tract. This aids normal elimination by reducing the
amount of time required for wastes to move through the digestive track. Fiber is
classified as insoluble and soluble. Insoluble fiber has been found to reduce the risk of
several forms of cancer. Soluble fiber, found in oat bran, dried beans, and some fruits and
vegetables, appears to be a factor in lowering blood cholesterol levels.
Many researchers believe that speeding up the passage of food through the
intestines decreases the risk of colon cancer because of the decreased time that cancercausing agents remain in contact with the intestinal wall. Increased fiber intake is also
thought to reduce the risk of coronary heart disease because certain types of fiber bind
with the cholesterol in the digestive track, preventing its absorption. Further,
consumption of adequate amounts of fiber has been associated with lowered incidences
of obesity, constipation, appendicitis, and diabetes.
The recommended amount of dietary fiber is about 25 grams per day. The best
way to increase dietary fiber is to eat more complex carbohydrates. Excessive
consumption of fiber may cause gastrointestinal discomfort and can lead to an increased
loss of calcium, phosphorous, iron, and zinc.
Proteins
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Proteins, found in meat, poultry, fish, beans, dairy products, and grains, are the
major source of nutrients used to build and repair tissues such as muscles, blood, internal
organs, skin hair, nails, and bones. Further, proteins are the key elements of the
antibodies that protect us from disease, of enzymes that control chemical activities in the
body and of hormones that regulate bodily functions. Each gram of protein yields about 4
calories of energy, similar to that of carbohydrates. The body uses proteins as a source of
energy only if there are not enough carbohydrates and fats available. Protein is used as a
last resource for energy.
The average recommended protein intake for men is approximately 58 to 63
grams per day while the average woman needs only 46 to 50 grams per day under normal
circumstances. This amount should account for 10 to 15 percent of the total calories
ingested per day. During adolescence the allowance is equal to 1 gram of protein per
kilogram of body weight. This decreases to 0.8 grams of protein per kilogram of body
weight at approximately 18 years of age. Most Americans do not have any difficulty in
meeting their protein requirement, consuming over 90 grams of protein daily, with about
70 percent of this coming from animal flesh and dairy products. Any excess protein is
stored just like other calories, as fat.
The basic structural units of proteins are molecules known as amino acids, the
building blocks of proteins. Twenty-two amino acids comprise most proteins. The human
body is not able to produce all of these amino acids. Those not produced in the human
body must be obtained through diet from other protein sources. These eight amino acids
not produced in the body are called essential amino acids. The sources for essential
amino acids are classified as complete or incomplete protein. Animal protein is a
complete protein. This protein naturally contains all the essential amino acids necessary
to supply the body’s needs. Primary sources are meats, milk, poultry, egg whites, fish,
beans and dairy products. Proteins from plant sources are often incomplete proteins in
that they are missing one or two of the essential amino acids. Proteins from plant sources
fall into three general categories: legumes (dried beans, peas, peanuts, and soy products),
grains (whole grains, corn and pasta products), and nuts and seeds. It is important that
people get all the essential amino acids and if they only eat incomplete proteins, then they
will be missing several essential amino acids.
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Fats
Fats have 9 calories per gram, which is more than twice as many calories per
gram than carbohydrates and proteins. The reason that people get fat from eating foods
high in fat is that they tend to have many more calories than foods with less fat.
However, an excess of calories from any type of food (proteins or carbohydrates) will
turn into fat. Fats do serve valuable purposes in that they aid in the transport and
absorption of fat-soluble vitamins, are used as stored energy, act as an insulator for body
heat, provide shock absorption, and provide essential fatty acids and fat-soluble vitamins.
For these reasons, it is not healthy to have a totally non-fat diet.
Currently, approximately 30 to 40 percent of typical American diets consist of fat,
with saturated fat accounting for about 40 percent of all fat. It is recommended that fat
intake should be about 25 to 30 percent of total calories per day with saturated fat no
more than 10 percent. For a 2,000-calorie diet, is about 65 grams of fat per day.
The most common form of fat circulating in the blood is triglycerides, making up
about 95 percent of the total fat in the bloodstream. When we eat too many calories, the
excess is converted into triglycerides in the liver, which are then stored in the body. The
remaining 5 percent of body fat, is composed of substances such as cholesterol, which
can accumulate on the inner walls of arteries. This accumulation causes a narrowing of
the channel through which the blood flows and leads to a hardening of the arteries known
as atherosclerosis. Cholesterol should not exceed 250 to 300 milligrams per day.
There are two major types of fat: saturated fat and unsaturated fat. Saturated fats
are those that do not melt at room temperature and are derived from animal sources, such
as meats, cheese, and butter. They are considered more likely to contribute to heart
disease and increased blood cholesterol levels. Butter is classified as saturated fat.
Unsaturated fats, found in vegetable oils, are those that remain in liquid form at room
temperature and are derived from plant sources such as corn, sunflowers, and olives.
Vitamins
Vitamins have no caloric value and provide no direct source of energy. They are
needed, however, because they are essential for normal growth, the regulation of body
activities, and they help the body use the proteins, carbohydrates, and fats it needs to
produce energy.
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There are two major classifications of vitamins: fat soluble and water-soluble.
Vitamins A, D, K and E are fat-soluble. That is, they are dissolved, absorbed through the
intestinal tract with the help of fats, and stored in the fatty tissues of the body. Taking in
high, high doses of fat-soluble vitamins can create problems in the body. Because watersoluble vitamins, including C and B-complex, are transported in body fluids and are not
stored, they must be ingested daily. Generally, water-soluble vitamins are excreted and
cause few toxicity problems.
It is possible that people may need to take nutritional supplements in order to get
adequate amounts of vitamins. The foods that we eat today are not able to supply us with
all the nutrients that we need because they have been grown in soils that are depleted and
over fertilized. Many of them have been refined, stored, transported and processed so
that they no longer have the same nutritional value. Not all supplements are created
equal—it is important to research various companies in order to ensure that you are
getting a high quality product.
Minerals
Minerals, inorganic elements found in the body and food, are components of all
cells, especially those found in hard parts of the body (bones, nails, teeth). Serving the
same purpose as vitamins, minerals are readily excreted, do not build up in the body, and
are usually not toxic. Again, a well-balanced diet should provide adequate minerals.
Minerals are classified in two groups: macrominerals and trace minerals.
Macrominerals are those body needs in fairly large amounts, including sodium, calcium,
phosphorous, magnesium, potassium, sulfur, and chloride. Trace minerals are needed in
smaller dosages and include, iron, zinc, manganese, copper, iodine, and cobalt. Three
important minerals that need further explanation are sodium, calcium, and iron.
Sodium is necessary for the regulation of blood and body fluids, the successful
transmission of nerve impulses, heart activity, and certain metabolic functions. The
average American consumes between 6,000 and 12,000 milligrams of sodium per day.
Experts suggest that all we need is about 1,100 to 3,000 milligrams of sodium per day
(this equals one-tenth of a teaspoon of salt). Excessive sodium may be harmful to those
who are salt sensitive or who have high blood pressure.
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Calcium is necessary for building strong bones and teeth, muscle contraction,
blood clotting, nerve impulse transmission, regulating heartbeat, and fluid balance within
cells. The RDA suggests that most people consume 1,200 milligrams of calcium per day,
with teenagers needing as much as 1,500 milligrams, especially female athletes. Every
day that you do not ingest enough calcium your body pulls it from your bones to use in
daily cell functions--so your bones will continue to grow weaker with continual calcium
deficiency possibly leading to increase fractures and eventually osteoporosis, an agerelated condition of insufficient bone mass. Ingesting too much caffeine can interfere
with calcium absorption, so for every soda a person drinks he/she should drink an extra
class of milk.
Iron deficiencies can lead to anemia, a problem resulting from the body’s inability
to produce hemoglobin, which causes a person to feel tired all the time. Women are most
at risk for anemia.
Water
Water is the most essential of all nutrients and should be the nutrient of greatest
concern to physically active individuals. Water is involved in almost every body process
including the digestion and absorption of food, the circulatory process, the elimination of
waste products of nutrient and body metabolism, the building and rebuilding of cells, and
the transportation of nutrients, temperature control, and fluid and electrolyte balance.
Further, water is the major component of the blood, which carries oxygen and nutrients to
the tissues and is responsible for maintaining cells in worker order.
Even in severe conditions, the average person can go for weeks without certain
vitamins and minerals before experiencing serious deficiency symptoms. Dehydration,
however, can cause serious problems within a matter of hours, and after a few days
without water, death is likely. It is recommended that everyone drink at least eight to ten
glasses if fluids per day. However, since water is contained in almost all foods, and
especially in fruits and vegetables, the actual amount needed each day may be somewhat
less than this for the average person. The amount of water actually needed by any one
individual will vary according to dietary factors, age, size, environmental temperature,
humidity levels, exercise, and the efficiency of the individual’s system.