Human Nutrition
| I | INTRODUCTION |
Human
Nutrition, study of how food affects the health and survival of the human
body. Human beings require food to grow, reproduce, and maintain good health.
Without food, our bodies could not stay warm, build or repair tissue, or
maintain a heartbeat. Eating the right foods can help us avoid certain diseases
or recover faster when illness occurs. These and other important functions are
fueled by chemical substances in our food called nutrients. Nutrients are
classified as carbohydrates, proteins, fats, vitamins, minerals, and water.
When we eat a meal, nutrients are released
from food through digestion. Digestion begins in the mouth by the action of
chewing and the chemical activity of saliva, a watery fluid that contains
enzymes, certain proteins that help break down food. Further digestion occurs as
food travels through the stomach and the small intestine, where digestive
enzymes and acids liquefy food and muscle contractions push it along the
digestive tract. Nutrients are absorbed from the inside of the small intestine
into the bloodstream and carried to the sites in the body where they are needed.
At these sites, several chemical reactions occur that ensure the growth and
function of body tissues. The parts of foods that are not absorbed continue to
move down the intestinal tract and are eliminated from the body as feces.
Once digested, carbohydrates, proteins, and
fats provide the body with the energy it needs to maintain its many functions.
Scientists measure this energy in kilocalories, the amount of energy needed to
raise 1 kilogram of water 1 degree Celsius. In nutrition discussions, scientists
use the term calorie instead of kilocalorie as the standard unit of measure in
nutrition.
| II | ESSENTIAL NUTRIENTS |
Nutrients are classified as essential or
nonessential. Nonessential nutrients are manufactured in the body and do not
need to be obtained from food. Examples include cholesterol, a fatlike substance
present in all animal cells. Essential nutrients must be obtained from food
sources, because the body either does not produce them or produces them in
amounts too small to maintain growth and health. Essential nutrients include
water, carbohydrates, proteins, fats, vitamins, and minerals.
An individual needs varying amounts of each
essential nutrient, depending upon such factors as gender and age. Specific
health conditions, such as pregnancy, breast-feeding, illness, or drug use, make
unusual demands on the body and increase its need for nutrients. Dietary
guidelines, which take many of these factors into account, provide general
guidance in meeting daily nutritional needs.
| III | WATER |
If the importance of a nutrient is judged
by how long we can do without it, water ranks as the most important. A person
can survive only eight to ten days without water, whereas it takes weeks or even
months to die from a lack of food. Water circulates through our blood and
lymphatic system, transporting oxygen and nutrients to cells and removing wastes
through urine and sweat. Water also maintains the natural balance between
dissolved salts and water inside and outside of cells. Our joints and soft
tissues depend on the cushioning that water provides for them. While water has
no caloric value and therefore is not an energy source, without it in our diets
we could not digest or absorb the foods we eat or eliminate the body’s digestive
waste.
The human body is 65 percent water, and it
takes an average of eight to ten cups to replenish the water our bodies lose
each day. How much water a person needs depends largely on the volume of urine
and sweat lost daily, and water needs are increased if a person suffers from
diarrhea or vomiting or undergoes heavy physical exercise. Water is replenished
by drinking liquids, preferably those without caffeine or alcohol, both of which
increase the output of urine and thus dehydrate the body. Many foods are also a
good source of water—fruits and vegetables, for instance, are 80 to 95 percent
water; meats are made up of 50 percent water; and grains, such as oats and rice,
can have as much as 35 percent water.
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| Carbohydrate is an energy component of diet ,it is a biological compound containing Carbon, Hydrogen, and Oxygen that is an important source of food and energy. |
Monosaccharide: is simplest sugar, a simple sugar such as glucose or fructose that cannot be
broken down into simpler sugars.
Disaccharide: is a sugar consisting of two linked monosaccharide units.
Polysaccharides: have enormous molecules made up of one type or several types of monosaccharide units.
The carbohydrate group consists principally of sugar,
starch, dextrin, cellulose, and glycogen,
substances that constitute an important part of the human diet and that of many
animals. The simplest of them are the simple sugars, or monosaccharides, which
contain either an aldehyde or a ketone group. The most
important is glucose. Two monosaccharide molecules joined together
by an oxygen atom, with the elimination of a molecule of water, yield a
disaccharide, of which the most important are sucrose (ordinary
cane sugar), lactose, and maltose. Polysaccharides
have enormous molecules made up of one type or several types of monosaccharide
units—about 10 in glycogen, for example; 25 in starch; and 100 to 200 in
cellulose.
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Carbohydrates are the human body’s key
source of energy, providing 4 calories of energy per gram. When carbohydrates
are broken down by the body, the sugar glucose is produced; glucose is critical
to help maintain tissue protein, metabolize fat, and fuel the central nervous
system.
Glucose is absorbed into the bloodstream
through the intestinal wall. Some of this glucose goes straight to work in our
brain cells and red blood cells, while the rest makes its way to the liver and
muscles, where it is stored as glycogen (animal starch), and to fat
cells, where it is stored as fat. Glycogen is the body’s auxiliary energy
source, tapped and converted back into glucose when we need more energy.
Although stored fat can also serve as a backup source of energy, it is never
converted into glucose. Fructose and galactose, other sugar products resulting
from the breakdown of carbohydrates, go straight to the liver, where they are
converted into glucose.
Starches and sugars are the major
carbohydrates. Common starch foods include whole-grain breads and cereals,
pasta, corn, beans, peas, and potatoes. Naturally occurring sugars are found in
fruits and many vegetables; milk products; and honey, maple sugar, and sugar
cane. Foods that contain starches and naturally occurring sugars are referred to
as complex carbohydrates, because their molecular complexity requires our bodies
to break them down into a simpler form to obtain the much-needed fuel, glucose.
Our bodies digest and absorb complex carbohydrates at a rate that helps maintain
the healthful levels of glucose already in the blood.
In contrast, simple sugars, refined from
naturally occurring sugars and added to processed foods, require little
digestion and are quickly absorbed by the body, triggering an unhealthy chain of
events. The body’s rapid absorption of simple sugars elevates the levels of
glucose in the blood, which triggers the release of the hormone insulin. Insulin
reins in the body’s rising glucose levels, but at a price: Glucose levels may
fall so low within one to two hours after eating foods high in simple sugars,
such as candy, that the body responds by releasing chemicals known as
anti-insulin hormones. This surge in chemicals, the aftermath of eating a candy
bar, can leave a person feeling irritable and nervous.
Many processed foods not only contain high
levels of added simple sugars, they also tend to be high in fat and lacking in
the vitamins and minerals found naturally in complex carbohydrates.
Nutritionists often refer to such processed foods as junk foods and say that
they provide only empty calories, meaning they are loaded with calories from
sugars and fats but lack the essential nutrients our bodies need.
In addition to starches and sugars, complex
carbohydrates contain indigestible dietary fibers. Although such fibers provide
no energy or building materials, they play a vital role in our health. Found
only in plants, dietary fiber is classified as soluble or insoluble. Soluble
fiber, found in such foods as oats, barley, beans, peas, apples, strawberries,
and citrus fruits, mixes with food in the stomach and prevents or reduces the
absorption by the small intestine of potentially dangerous substances from food.
Soluble fiber also binds dietary cholesterol and carries it out of the body,
thus preventing it from entering the bloodstream where it can accumulate in the
inner walls of arteries and set the stage for high blood pressure, heart
disease, and strokes. Insoluble fiber, found in vegetables, whole-grain
products, and bran, provides roughage that speeds the elimination of feces,
which decreases the time that the body is exposed to harmful substances,
possibly reducing the risk of colon cancer. Studies of populations with
fiber-rich diets, such as Africans and Asians, show that these populations have
less risk of colon cancer compared to those who eat low-fiber diets, such as
Americans. In the United States, colon cancer is the third most common cancer
for both men and women, but experts believe that, with a proper diet, it is one
of the most preventable types of cancer.
Nutritionists caution that most Americans
need to eat more complex carbohydrates. In the typical American diet, only 40 to
50 percent of total calories come from carbohydrates—a lower percentage than
found in most of the world. To make matters worse, half of the carbohydrate
calories consumed by the typical American come from processed foods filled with
simple sugars. Experts recommend that these foods make up no more that 10
percent of our diet, because these foods offer no nutritional value. Foods rich
in complex carbohydrates, which provide vitamins, minerals, some protein, and
dietary fiber and are an abundant energy source, should make up roughly 50
percent of our daily calories.
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| PROTEINS |
Protein: is a complex natural substance that has a globular or fibrous structure composed of
linked amino acids.
Proteins are essential to the structure and function of all living cells.
| V | PROTEINS |
Dietary proteins are powerful compounds that
build and repair body tissues, from hair and fingernails to muscles. In addition
to maintaining the body’s structure, proteins speed up chemical reactions in the
body, serve as chemical messengers, fight infection, and transport oxygen from
the lungs to the body’s tissues. Although protein provides 4 calories of energy
per gram, the body uses protein for energy only if carbohydrate and fat intake
is insufficient. When tapped as an energy source, protein is diverted from the
many critical functions it performs for our bodies.
Proteins are made of smaller units called
amino acids. Of the more than 20 amino acids our bodies require, eight (nine in
some older adults and young children) cannot be made by the body in sufficient
quantities to maintain health. These amino acids are considered essential and
must be obtained from food. When we eat food high in proteins, the digestive
tract breaks this dietary protein into amino acids. Absorbed into the
bloodstream and sent to the cells that need them, amino acids then recombine
into the functional proteins our bodies need.
Animal proteins, found in such food as eggs,
milk, meat, fish, and poultry, are considered complete proteins because they
contain all of the essential amino acids our bodies need. Plant proteins, found
in vegetables, grains, and beans, lack one or more of the essential amino acids.
However, plant proteins can be combined in the diet to provide all of the
essential amino acids. A good example is rice and beans. Each of these foods
lacks one or more essential amino acids, but the amino acids missing in rice are
found in the beans, and vice versa. So when eaten together, these foods provide
a complete source of protein. Thus, people who do not eat animal products
(see Vegetarianism) can meet their protein needs with diets rich in
grains, dried peas and beans, rice, nuts, and tofu, a soybean product.
Experts recommend that protein intake make up
only 10 percent of our daily calorie intake. Some people, especially in the
United States and other developed countries, consume more protein than the body
needs. Because extra amino acids cannot be stored for later use, the body
destroys these amino acids and excretes their by-products. Alternatively,
deficiencies in protein consumption, seen in the diets of people in some
developing nations, may result in health problems. Marasmus and kwashiorkor,
both life-threatening conditions, are the two most common forms of protein
malnutrition.
Some health conditions, such as illness,
stress, and pregnancy and breast-feeding in women, place an enormous demand on
the body as it builds tissue or fights infection, and these conditions require
an increase in protein consumption. For example, a healthy woman normally needs
45 grams of protein each day. Experts recommend that a pregnant woman consume 55
grams of protein per day, and that a breast-feeding mother consume 65 grams to
maintain health.
A man of average size should eat 57 grams of
protein daily. To support their rapid development, infants and young children
require relatively more protein than do adults. A three-month-old infant
requires about 13 grams of protein daily, and a four-year-old child requires
about 22 grams. Once in adolescence, sex hormone differences cause boys to
develop more muscle and bone than girls; as a result, the protein needs of
adolescent boys are higher than those of girls.
| FATS |
Fats are esters of glycerol and fatty acids.
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| Fatty Acids + Glycerol = Fat Molecule |
| VI | FATS |
Fats, which provide 9 calories of energy per
gram, are the most concentrated of the energy-producing nutrients, so our bodies
need only very small amounts. Fats play an important role in building the
membranes that surround our cells and in helping blood to clot. Once digested
and absorbed, fats help the body absorb certain vitamins. Fat stored in the body
cushions vital organs and protects us from extreme cold and heat.
Fat consists of fatty acids attached to a
substance called glycerol. Dietary fats are classified as saturated,
monounsaturated, and polyunsaturated according to the structure of their fatty
acids. Animal fats—from eggs, dairy products, and meats—are high in saturated
fats and cholesterol, a chemical substance found in all animal fat. Vegetable
fats—found, for example, in avocados, olives, some nuts, and certain vegetable
oils—are rich in monounsaturated and polyunsaturated fat. As we will see, high
intake of saturated fats can be unhealthy.
To understand the problem with eating too
much saturated fat, we must examine its relationship to cholesterol. High levels
of cholesterol in the blood have been linked to the development of heart
disease, strokes, and other health problems. Despite its bad reputation, our
bodies need cholesterol, which is used to build cell membranes, to protect nerve
fibers, and to produce vitamin D and some hormones, chemical messengers that
help coordinate the body’s functions. We just do not need cholesterol in our
diet. The liver, and to a lesser extent the small intestine, manufacture all the
cholesterol we require. When we eat cholesterol from foods that contain
saturated fatty acids, we increase the level of a cholesterol-carrying substance
in our blood that harms our health.
Cholesterol, like fat, is a lipid—an organic
compound that is not soluble in water. In order to travel through blood,
cholesterol therefore must be transported through the body in special carriers,
called lipoproteins. High-density lipoproteins (HDLs) remove cholesterol from
the walls of arteries, return it to the liver, and help the liver excrete it as
bile, a liquid acid essential to fat digestion. For this reason, HDL is called
“good” cholesterol.
Low-density lipoproteins (LDLs) and
very-low-density lipoproteins (VLDLs) are considered “bad” cholesterol. Both
LDLs and VLDLs transport cholesterol from the liver to the cells. As they work,
LDLs and VLDLs leave plaque-forming cholesterol in the walls of the arteries,
clogging the artery walls and setting the stage for heart disease. Almost 70
percent of the cholesterol in our bodies is carried by LDLs and VLDLs, and the
remainder is transported by HDLs. For this reason, we need to consume dietary
fats that increase our HDLs and decrease our LDL and VLDL levels.
Saturated fatty acids—found in foods ranging
from beef to ice cream, to mozzarella cheese to doughnuts—should make up no more
than 10 percent of a person’s total calorie intake each day. Saturated fats are
considered harmful to the heart and blood vessels because they are thought to
increase the level of LDLs and VLDLs and decrease the levels of HDLs.
Monounsaturated fats—found in olive, canola,
and peanut oils—appear to have the best effect on blood cholesterol, decreasing
the level of LDLs and VLDLs and increasing the level of HDLs. Polyunsaturated
fats—found in margarine and sunflower, soybean, corn, and safflower oils—are
considered more healthful than saturated fats. However, if consumed in excess
(more than 10 percent of daily calories), they can decrease the blood levels of
HDLs.
Most Americans obtain 15 to 50 percent of
their daily calories from fats. Health experts consider diets with more than 30
percent of calories from fat to be unsafe, increasing the risk of heart disease.
High-fat diets also contribute to obesity, which is linked to high blood
pressure (see hypertension) and diabetes mellitus. A diet high in both
saturated and unsaturated fats has also been associated with greater risk of
developing cancers of the colon, prostate, breast, and uterus. Choosing a diet
that is low in fat and cholesterol is critical to maintaining health and
reducing the risk of life-threatening disease.
| VII | VITAMINS AND MINERALS |
Both vitamins and minerals are needed by
the body in very small amounts to trigger the thousands of chemical reactions
necessary to maintain good health. Many of these chemical reactions are linked,
with one triggering another. If there is a missing or deficient vitamin or
mineral—or link—anywhere in this chain, this process may break down, with
potentially devastating health effects. Although similar in supporting critical
functions in the human body, vitamins and minerals have key differences.
Among their many functions, vitamins
enhance the body’s use of carbohydrates, proteins, and fats. They are critical
in the formation of blood cells, hormones, nervous system chemicals known as
neurotransmitters, and the genetic material deoxyribonucleic acid (DNA).
Vitamins are classified into two groups: fat soluble and water soluble.
Fat-soluble vitamins, which include vitamins A, D, E, and K, are usually
absorbed with the help of foods that contain fat. Fat containing these vitamins
is broken down by bile, a liquid released by the liver, and the body then
absorbs the breakdown products and vitamins. Excess amounts of fat-soluble
vitamins are stored in the body’s fat, liver, and kidneys. Because these
vitamins can be stored in the body, they do not need to be consumed every day to
meet the body’s needs.
Water-soluble vitamins, which include
vitamins C (also known as ascorbic acid), B1 (thiamine), B2 (riboflavin), B3
(niacin), B6, B12, and folic acid, cannot be stored and rapidly leave the body
in urine if taken in greater quantities than the body can use. Foods that
contain water-soluble vitamins need to be eaten daily to replenish the body’s
needs.
In addition to the roles noted in the
vitamin and mineral chart accompanying this article, vitamins A (in the form of
beta-carotene), C, and E function as antioxidants, which are vital in countering
the potential harm of chemicals known as free radicals. If these chemicals
remain unchecked they can make cells more vulnerable to cancer-causing
substances. Free radicals can also transform chemicals in the body into
cancer-causing agents. Environmental pollutants, such as cigarette smoke, are
sources of free radicals.
Minerals are minute amounts of metallic
elements that are vital for the healthy growth of teeth and bones. They also
help in such cellular activity as enzyme action, muscle contraction, nerve
reaction, and blood clotting. Mineral nutrients are classified as major elements
(calcium, chlorine, magnesium, phosphorus, potassium, sodium, and sulfur) and
trace elements (chromium, copper, fluoride, iodine, iron, selenium, and
zinc).
Vitamins and minerals not only help the
body perform its various functions, but also prevent the onset of many
disorders. For example, vitamin C is important in maintaining our bones and
teeth; scurvy, a disorder that attacks the gums, skin, and muscles, occurs in
its absence. Diets lacking vitamin B1, which supports neuromuscular function,
can result in beriberi, a disease characterized by mental confusion, muscle
weakness, and inflammation of the heart. Adequate intake of folic acid by
pregnant women is critical to avoid nervous system defects in the developing
fetus. The mineral calcium plays a critical role in building and maintaining
strong bones; without it, children develop weak bones and adults experience the
progressive loss of bone mass known as osteoporosis, which increases their risk
of bone fractures.
Vitamins and minerals are found in a wide
variety of foods, but some foods are better sources of specific vitamins and
minerals than others. For example, oranges contain large amounts of vitamin C
and folic acid but very little of the other vitamins. Milk contains large
amounts of calcium but no vitamin C. Sweet potatoes are rich in vitamin A, but
white potatoes contain almost none of this vitamin. Because of these differences
in vitamin and mineral content, it is wise to eat a wide variety of foods.
| VIII | TOO LITTLE AND TOO MUCH FOOD |
When the body is not given enough of any
one of the essential nutrients over a period of time, it becomes weak and less
able to fight infection. The brain may become sluggish and react slowly. The
body taps its stored fat for energy, and muscle is broken down to use for
energy. Eventually the body withers away, the heart ceases to pump properly, and
death occurs—the most extreme result of a dietary condition known as
deficiency-related malnutrition.
Deficiency diseases result from inadequate
intake of the major nutrients. These deficiencies can result from eating foods
that lack critical vitamins and minerals, from a lack of variety of foods, or
from simply not having enough food. Malnutrition can reflect conditions of
poverty, war, famine, and disease. It can also result from eating disorders,
such as anorexia nervosa and bulimia.
Although malnutrition is more commonly
associated with dietary deficiencies, it also can develop in cases where people
have enough food to eat, but they choose foods low in essential nutrients. This
is the more common form of malnutrition in developed countries such as the
United States. When poor food choices are made, a person may be getting an
adequate, or excessive, amount of calories each day, yet still be
undernourished. For example, iron deficiency is a common health problem among
women and young children in the United States, and low intake of calcium is
directly related to poor quality bones and increased fracture risk, especially
in the elderly.
A diet of excesses may also lead to other
nutritional problems. Obesity is the condition of having too much body fat. It
has been linked to life-threatening diseases including diabetes mellitus, heart
problems, and some forms of cancer. Eating too many salty foods may contribute
to high blood pressure (see hypertension), an often undiagnosed condition
that causes the heart to work too hard and puts strain on the arteries. High
blood pressure can lead to strokes, heart attacks, and kidney failure. A diet
high in cholesterol and fat, particularly saturated fat, is the primary cause of
atherosclerosis, which results when fat and cholesterol deposits build up in the
arteries, causing a reduction in blood flow.
| IX | MAKING GOOD NUTRITIONAL CHOICES |
To determine healthful nutrition standards,
the Food and Nutrition Board of the National Academy of Sciences (NAS), a
nonprofit, scholarly society that advises the United States government,
periodically assembles committees of national experts to update and assess
nutrition guidelines. The NAS first published its Recommended Dietary Allowances
(RDAs) in 1941. An RDA reflects the amount of a nutrient in the diet that should
decrease the risk of chronic disease for most healthy individuals. The NAS
originally developed the RDAs to ensure that World War II soldiers stationed
around the world received enough of the right kinds of foods to maintain their
health. The NAS periodically has updated the RDAs to reflect new knowledge of
nutrient needs.
In the late 1990s the NAS decided that the
RDAs, originally developed to prevent nutrient deficiencies, needed to serve
instead as a guide for optimizing health. Consequently, the NAS created Dietary
Reference Intakes (DRIs), which incorporate the RDAs and a variety of new
dietary guidelines. As part of this change, the NAS replaced some RDAs with
another measure, called Adequate Intake (AI). Although the AI recommendations
are often the same as those in the original RDA, use of this term reflects that
there is not enough scientific evidence to set a standard for the nutrient.
Calcium, which has an AI of 1,000 to 1,300 mg per day, is not an RDA because
scientists do not yet know how much calcium is needed to prevent
osteoporosis.
Tolerable Upper Intake Level (UL) designates
the highest recommended intake of a nutrient for good health. If intake exceeds
this amount, health problems may develop. Calcium, for instance, has a UL of
2500 mg per day. Scientists know that more than this amount of calcium taken
every day can interfere with the absorption of iron, zinc, and magnesium and may
result in kidney stones or kidney failure.
Estimated Average Requirement (EAR) reflects
the amount of a particular nutrient that meets the optimal needs of half the
individuals in a specified group. For example, the NAS cites an EAR of 45 to 90
grams of protein for men aged 18 to 25. This figure means that half the men in
that population need a daily intake of protein that falls within that
range.
To simplify the complex standards
established by the NAS, the United States Department of Agriculture (USDA)
created the Food Guide Pyramid, a visual display of the relative
importance to health of six food groups common to the American diet. The pyramid
recommends a range of the number of servings to choose from each group, based on
the nutritional needs of males and females and different age groups. In 2005 the
pyramid was updated to accommodate different levels of physical exercise and
caloric intake resulting in 12 unique pyramids tailored to fit individual needs.
In an effort to provide additional
nutritional guidance and reduce the incidence of diet-related cancers, the
National Cancer Institute developed the 5-a-Day Campaign for Better Health,
a program that promotes the practice of eating five to nine servings of
fruits and vegetables daily. Studies of populations that eat many fruits and
vegetables reveal a decreased incidence of diet-related cancers. Laboratory
studies have shown that many fruits and vegetables contain phytochemicals,
substances that appear to limit the growth of cancer cells.
Many people obtain most of their nutrition
information from a food label called the Nutrition Facts panel. This label is
mandatory for most foods that contain more than one ingredient, and these foods
are mostly processed foods. Labeling remains voluntary for raw meats, fresh
fruits and vegetables, foods produced by small businesses, and those sold in
restaurants, food stands, and local bakeries.
The Nutrition Facts panel highlights a
product’s content of fat, saturated fat, cholesterol, sodium, dietary fiber,
vitamins A and C, and the minerals calcium and iron. The stated content of these
nutrients must be based on a standard serving size, as defined by the Food and
Drug Administration (FDA). Food manufacturers may provide information about
other nutrients if they choose. However, if a nutritional claim is made on a
product’s package, the appropriate nutrient content must be listed. For example,
if the package says “high in folic acid,” then the folic acid content in the
product must be given in the Nutrition Facts panel.
The Nutrition Facts panel also includes
important information in a column headed % Daily Value (DV). DVs tell how the
food item meets the recommended daily intakes of fat, saturated fat,
cholesterol, carbohydrates, dietary fiber, and protein necessary for nutritional
health based on the total intake recommended for a person consuming 2,000
calories per day. One portion from a can of soup, for example, may have less
than 2 percent of the recommended daily value for cholesterol intake.
Health-conscious consumers can use the
Nutrition Facts panel to guide their food choices. For example, based on a daily
diet of 2,000 calories, nutrition experts recommend that no more than 30 percent
of those calories should be from fat, which would allow for a daily intake of
around 65 grams of fat. A Nutrition Facts panel may indicate that a serving of
one brand of macaroni and cheese contains 14 grams of fat, or a % DV of 25
percent. This tells the consumer that a serving of macaroni and cheese provides
about one-fourth of the suggested healthy level of daily fat intake. If another
brand of macaroni and cheese displays a % DRV of 10 percent fat, the
nutrition-conscious consumer would opt for this brand.
Nutritionists and other health experts help
consumers make good food choices. People who study nutrition in college may
refer to themselves as nutritionists; often, however, the term refers to a
scientist who has pursued graduate education in this field. A nutritionist may
also be a dietitian. Dietitians are trained in nutrition, food chemistry, and
diet planning. In the United States, dietitians typically have graduated from a
college program accredited by the American Dietetic Association (ADA), completed
an approved program of clinical experience, and passed the ADA’s registration
examination to earn the title Registered Dietitian (RD).
Reasons of Famine ):
- Unequal distribution of food.
- Incorrect balance and carry-out of the duty by WHO(World Health Organisation), WFP (World Food Programme.)
- insufficient, or imbalanced consumption of nutrients
- Less intake of vitamins & minerals, which are necessary for food items to be assimilated by the body with efficiency.
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