Healthy Food And Nutrients
Food is one
of the basic necessities of life. Food contains nutrients—substances essential for the growth, repair, and
maintenance of body tissues and for
the regulation of vital processes.
Nutrients provide the energy our
bodies need to function.
The energy in food is
measured in units called calories. Age,
sex, weight, height, and level of activity determine the number
of calories a person needs each day. Depending on age, sex, and
activity level, the recommended daily caloric intake for a child aged 11 to 14
can range anywhere from 1,600 to 2,600 calories per day, with
sedentary girls needing the fewest calories and active boys needing
the most. For adults, this can range from 1,800 to about 3,000.
Kinds of
Nutrients
Scientists divide nutrients into six
major groups:
- carbohydrates
- fats
- proteins
- minerals
- vitamins
- water
Most foods contain all or most nutrient groups, in
different amounts.
Carbohydrates provide energy for
the body. Nearly all the carbohydrates we eat come from plants. They
include starches found in cereal grains and
plants like potatoes and yams. Sugars,
found in fruits, vegetables, and milk,
are also carbohydrates. Sugarcane and sugar beets are
grown specifically for their high sugar content.
Many of
the starches and sugars we eat have
been processed into products, such as flour and corn
syrup. These processed carbohydrates are used in cookies,
cakes, breads, pastas, and pies.
Fats provide more than twice as
much energy as carbohydrates. They also help protect and insulate the
body and its internal organs.
Common fats include vegetable oils, such as soybean, cottonseed, and corn oil.
They are used in cooking and in the processing of
many foods.
Common fats include vegetable
oils, such as soybean, cottonseed,
and corn oil. They are used in
cooking and in the processing of many foods.
Fats that come from animal products include butter and lard.
Eggs, milk, cheese, meats, poultry, and fish also contain high levels
of fats.
Proteins are the body’s
chief tissue-builders. They help keep skin, bones, muscles, and blood
healthy. Proteins also help regulate bodily processes, including
transporting oxygen and nutrients into
and out of cells; the clotting of blood; and the formation of
antibodies, which help fight disease.
Animal products, such as beef, fish, poultry, eggs, and dairy products, are high
in protein. Grains, nuts, and some beans are
also protein-rich foods.
Minerals and vitamins are
called micronutrients because they
are needed in very small quantities compared
with carbohydrates, fats, and proteins (known as macronutrients). Minerals provide
building materials for the body and help regulate its activities, much
as proteins do. Calcium and phosphorus build strong bones and teeth, iron contributes to healthy blood, and iodine helps keep the thyroid gland working.
Vitamins help the body make full use of
other nutrients by assisting the chemical reactions that make
those nutrients work. For example, vitamin B1, or thiamine, helps regulate the release
of energy from carbohydrates, promotes a healthy appetite, and aids the functioning of the nervous system. Vitamin
D helps in the growth and maintenance of healthy bones.
Other essentials for the body’s health
include water, oxygen, and fiber.
Some scientists include water in the list of basic nutrients. Water makes
up more than half of a human body’s weight. It is involved in most
body processes, such as the regulation of temperature, the transporting
of nutrients into cells, and the elimination of waste products
from cells.
Oxygen is not a nutrient, since it is
breathed in and not eaten, but it is essential to life. It permits
the release of energy from food inside the body.
Fiber is indigestible material
found in most plant foods. It adds bulk to the diet, helping to keep the intestines healthy. Fiber-rich foods include
whole grains, dried beans, and fresh fruits and vegetables.
A healthy diet contains a balanced mix
of different foods that together provide
all essential nutrients. Malnutrition is
the lack of a balanced diet. Too few nutrients, too
many nutrients, or an imbalance of nutrients (too
many carbohydrates, for instance, and not
enough fruits and vegetables) can lead to malnutrition.
Undernutrition is a form
of malnutrition. It is usually linked to hunger.
Undernutrition happens when the body does not get enough food to
meet its needs. Many diseases and even death are caused by lack
of food. Death due to lack of food is called starvation.
To get the right amounts of nutrients,
people need to select from a range
of food types: cereal grains; fruits and vegetables; legumes, meat, poultry, fish, and eggs;
and milk and dairy products. A food pyramid outlines the suggested amount of
these different types of foods people should eat each day.
Cereal
Grains
Cereal grains are the edible seeds of certain grasses. People have grown them since the beginning
of agriculture. Today, the most commonly
grown grains are wheat, rice, and corn (maize). Other important grains are sorghum, millet, barley, oats,
and rye.
Worldwide, cereal grains are the
most important food staples. They
are eaten almost daily by large populations. They supply a significant percentage of
the calories consumed by the world’s
population. Cereal grains and the products made from them
provide food not only for people, but also for livestock, such as cattle,
chickens, and hogs.
Throughout the world, more wheat is
planted than any other grain. Wheat is the chief ingredient in
most breads, cookies, cakes, crackers, pastas, and some breakfast cereals. China, the United States,
Russia, Ukraine, India, France, and Canada are major wheat-producing
countries. Wheat, often eaten as bread, serves as the
principal food grain for people living in regions with temperate climates.
Rice, an Asian tropical grass,
is a food staple for more than half the world’s population. More
than 90 percent of the world’s total rice crop is
produced and eaten in South and East Asia. Rice is also
a food staple for people in parts of Africa and Latin America.
This cereal grain thrives in a warm, humid climate with heavy rainfall or wet
ground. It is often grown in flooded fields
called rice paddies.
Hominy grits, corn bread,
popcorn, and tortillas are all made
with corn. Outside the United States, this grain is
called maize. Although native to the Americas, maize is
now cultivated throughout most of
the world and is a staple food in many areas. It grows in
various soils and climates and
at different elevations. American farmers produce over 30 percent of the
world’s corn; of that 40 percent, most of it is used to
feed livestock. Corn is also used to produce sweeteners, such
as corn syrup and cornstarch.
Sorghum and millet are
other grains commonly used as livestock feeds.
These grains are also staple foods for people in parts of
Africa and Asia, where they are used in breads, porridges, and cakes.
Three other grains—barley, oats,
and rye—are important in many regions. Barley thrives
in a wide range of climates. One type of barley is the source
of malt for making beer. Barley is also used in making vinegar, malt extract, and beverages similar to milk.
Pearl barley, the most popular form of this grain, is often used in
soups and other foods.
Oats and rye were domesticated much later than
other grains. Oats are used mainly as livestock feed,
but also go into oatmeal and other breakfast cereals.
After wheat, rye is the second most common grain used
as a bread flour; the two are often mixed together in breads. Bread made
with rye alone, called black bread,
is popular in many European countries.
Fruits
and Vegetables
The term “fruit” has several meanings. To
a botanist, it means the part of a plant
that contains seeds. According to this definition, fruits include
most nuts, as well as vegetables, such as cucumbers and tomatoes.
To most of us, though, “fruit” is defined as the
soft, edible, seed-bearing part of a perennial plant.
A perennial is a plant that lives for more than one growing season.
Fresh fruits are rich
in carbohydrates, vitamins, minerals, and fiber. They can
be preserved by freezing, canning, or drying.
Different fruits grow in
different climates, and may not grow well in climates that are
too cold, hot, dry, or wet. Based on the kind of climate in which
they grow, fruits can be classified in different
groups: temperate fruits, subtropical fruits,
and tropical fruits.
Temperate fruits grow best where there
is a well-defined cold season, as in the U.S. states of Washington and Oregon. Temperate fruits include
apples, berries, grapes, pears, plums, and peaches.
Subtropical fruits thrive where
temperatures are mostly warm year-round. The area around the
Mediterranean Sea has a subtropical climate. Citrus fruits, such as lemons, oranges,
grapefruits, dates, pomegranates, and some types of avocadoes,
are subtropical fruits.
Tropical fruits require a
hot climate to grow. Tropical fruits, such as bananas,
mangoes, and papayas, grow in hot, humid areas like the Philippines.
Vegetables are the edible parts
of herbaceous plants. Herbaceous plants, sometimes just
called herbs, have stems that
are softer and less woody than those of trees and shrubs. Vegetables are
good sources of fiber, minerals, and vitamins.
Most vegetables are annuals,
living for only one growing season.
Vegetables can be roots, leaves, stems, seeds, or bulbs. For example, carrots, radishes, and beets
are roots. Cabbage, celery, lettuce, and spinach are leaves or leafstalks. Heads of broccoli are flower stalks
topped by thick clusters of flower buds. Asparagus is a stem. Cucumbers,
eggplants, and tomatoes contain the seeds of the plant. Garlic,
leeks, and onions are bulbs.
Some plants, called tubers, have a special type of
underground stem that can be eaten fresh as a vegetable or
used as an ingredient in other dishes. In temperate regions, the
most important tuber is the potato. The potato was first
a food staple to indigenous cultures of the Andes of South America. Today,
major potato-growing countries include Russia, China, and Poland.
Important tropical tubers include
yams, cassavas, and taros. These tubers are
staple foods in many cultures. For instance, taro is a
major food crop of the islands of Polynesia, as well as West
Africa. Cassava is a staple food for more than 500 million
people in Africa and Latin America.
Legumes,
Meat, Poultry, Fish, and Eggs
Legumes are plants that are raised for
their edible seeds or seed pods. Peas, lima beans,
soybeans, peanuts, and lentils are
all legumes. Legumes that are harvested for
their dry seeds, such as beans or lentils, are called pulses. Pulses are food staples in
India and Pakistan.
Legumes and pulses contain high
amounts of protein. In addition, they supply iron,
other minerals, and vitamins.
The term “meat” usually refers to
the edible flesh of mammals,
such as cattle, pigs, and sheep. Meat is a
high-protein food and is rich in other nutrients, as well.
The United States, Australia, Russia, and
Argentina raise much of the world’s beef cattle. Beef can come from cows, bulls,
or steers. Cows are adult
female cattle. Bulls are adult male cattle capable of
reproduction. Steers are adult male cattle that have
been castrated, or been made incapable
of reproduction. Meat from very young cattle, or calves, is
called veal.
The world’s major hog producers include China,
the European Union, the United States, Brazil, and Russia. Meat from
hogs is called pork.
Lamb is meat from sheep less than a
year old. It is especially popular in the Middle East, Australia, and the
United Kingdom. Mutton, meat from
mature sheep, has a stronger flavor and a rougher texture than lamb. New
Zealand and Australia are the world’s largest exporters of
lamb and mutton.
Bison, water buffalo, camels, goats, and yaks are all
sources of meat. Wild animals, such as rabbits and deer, are also eaten
as meat. Meat from wild animals is called game.
“Poultry” refers to domesticated birds
that are raised for meat and eggs. Chickens are
an important food source for most of the world’s population.
Raising chickens is a major industry in many countries, including China, the
United States, Russia, and across the European Union. Ducks, turkeys, geese,
and guinea fowl are also raised
for food in many parts of the world.
Fish and shellfish are
probably the most popular meats worldwide. Fish provide about 15
percent of all animal proteins consumed by the world’s population.
Fish and shellfish are excellent sources
of vitamins and minerals. People eat fish raw or cooked, and preserve
it by canning, freezing, drying, salting, smoking, or pickling.
Most of the fish and shellfish people
eat come from the ocean. Tuna is one of the most popular ocean fish. Other fish
come from inland bodies of fresh water, such as lakes and rivers. Bass, perch,
and carp are popular freshwater fish worldwide.
An increasing amount of fish comes from fish
farms, where fish and shellfish are raised commercially. The cultivation of fish
and shellfish is called aquaculture.
Clams, oysters, crabs, and shrimp are popular
types of shellfish. Abalone, a kind of mollusk,
is another type of seafood. Conch, a large type of sea snail, is eaten in the
Florida Keys and in the West Indies. Eels, octopuses, squids, and mussels are
other popular seafoods.
Eggs are a source
of proteins, fats, minerals, and vitamins. Boiled, fried,
scrambled, or deviled, chicken eggs are popular around the world. They are also
used in a variety of baked goods. People also eat the eggs of other birds, such
as ducks and quail, and those of reptiles,
such as turtles and crocodiles. The eggs of certain fish, mainly sturgeon, are prepared as a delicacy known as caviar.
Milk
and Dairy Products
Much of the world’s milk,
cream, butter, yogurt, and cheese
come from dairy cows. However, goats, camels, reindeer, sheep, yaks,
and water buffalo supply milk products as well.
In much of Asia, people have traditionally
consumed “milk” made from soybeans. Soy milk is
made from soaking and grinding soybeans with
water. Soy milk contains about the
same protein as cow’s milk.
Milk and dairy products supply proteins, carbohydrates, fats,
and essential vitamins and minerals. The Maasai people of East Africa
use milk as a staple food, and it constitutes a huge part of
their diet. Yogurt, a fermented milk product,
is a staple food in parts of the Middle East and India.
Diet
People’s diets vary from one country
to another. Diets can also vary within a single country. Geographic differences explain part of this
variation. For example, people who live near the ocean might eat greater
amounts of fish than people who live farther inland. People living in cool
regions with short growing seasons depend on crops that mature
quickly, such as potatoes. In warm, wet lowlands where
the soil retains water, rice is often a staple.
Geographic factors are
less important today than they were a century ago. Improved methods
of agriculture and transportation,
as well as increased trade and tourism, have made more types
of food available to a wider variety of people.
Improved methods of food processing, preservation, storage, and shipping allow many people to
enjoy foods produced far from their homes. Spanish olive oil, French cheeses, and sardines from Norway, for example, are eaten
as far away as Australia.
Local traditions and customs play a role in
determining what foods people eat and how they are prepared. English
tradition encourages roast beef and Yorkshire
pudding, a type of bread, be eaten together. Many Asians
serve rice with almost every meal.
Economic factors also affect what people eat. In the U.S.
state of Maine, lobster is usually
a relatively inexpensive food. The shellfish is native to the
state’s coastal areas and has been a traditional food for hundreds of
years. However, lobster is a luxury item
in the Midwest, where it must be flown in. Lobster dishes served in
Iowa may cost two to three times what they do in Maine.
In developed countries, many people have enough
money to buy a variety of nutritious foods. Malnutrition is not
a large problem, and people have a long lifespan. But even in these countries, there
are many people who cannot buy these foods because resources are not
evenly distributed throughout the
population. In some places, healthy, nutritious food can be more
expensive than so-called “junk food,” which
has many calories but little nutritional benefit.
Even those who can afford
healthy food may eat poorly. The diets of many people in
developed countries are too high in the fats, salt, and
refined sugars found in junk food.
These diets are too low in fruits, vegetables,
and fiber.
In developing
countries, malnutrition is more common. A
poor harvest, flood, or drought may
cause famine, because the community or
nation is not economically able to import food.
The diets of the urban and rural populations of developing countries are
often quite different. People in urban areas eat
more processed foods, while people who live in rural areas
may have access to fresh milk, fruits, and vegetables. However,
people living in rural areas are the first to be affected by a
poor harvest.
Food
and Culture
People do not eat only to
obtain nutrients and ward off hunger and starvation.
People’s eating habits are strongly influenced by culture. Rituals around preparing, sharing, and
consuming food serve social roles as well as biological ones.
Religion sometimes plays a role in what, and when, people
eat. Followers of the Jain religion,
for example, strongly believe in nonviolence toward all living things.
Strict Jains never eat meat. Many Jains also refrain
from eating potatoes and other tubers because many small organisms are harmed as
the tubers are pulled from the earth.
Jewish kashrut law
and Muslim dhabihah law outline many rules for eating.
Both include a ban on pork. Food that is prepared according
to kashrut law is called kosher,
while food that is prepared according to dhabihah law is
called halal.
During the month of Ramadan, Muslims fast, or avoid eating,
during daylight hours. Typically, Muslims will eat one meal before
dawn and one after sunset, but nothing at all while the sun is
shining. Ramadan is considered a time for inner reflection, devotion
to God, and self-control.
Feasting is also an important ritual, both for
religious and nonreligious reasons. Most religious fasting periods,
such as Ramadan, are followed by holiday feasts. Eid al-Fitr is the Islamic holiday following Ramadan.
One of the ways Muslims celebrate Eid is to donate food to
the poor.
Nonreligious holidays often
include feasts as well. In the United States, people gather to eat
turkey, stuffing, cranberry sauce, and pumpkin pie on Thanksgiving. In China,
families celebrate the Chinese New Year with foods that symbolize
luck and prosperity, such as long noodles, chickens, fish, oysters, dumplings,
tangerines, oranges, and sticky rice cakes.
Many people make dietary choices based
on ethics—beliefs about what is right
and wrong. For instance, some people choose not to eat meat out of
concern for the environment. Livestock is one of the leading
contributors to carbon emissions, and
some people reduce the amount of beef they eat to reduce their “carbon footprint.” Many people avoid
eating meat out of concern for animal welfare.
Vegetarians avoid eating all meat and fish. Vegans avoid all animal products, including
eggs, milk, cheese, and honey. Some people who are
not vegetarians may raise or buy humanely produced
animal products such as free-range chicken
and grass-fed beef.
Other ethics-based food practices
include choosing organic or locally
grown foods. People who choose organic foods may do so
because of the reduced number of chemicals in
the food. Organic food relies little on genetic modification or pesticides. Organic food also
releases fewer chemicals into the environment in the form of runoff.
The “locavore”
movement values the reduced environmental impact of local foods. There
are fewer transportation costs, such as greenhouse gas emissions, with
local foods.
The way we serve and eat food is as
culturally important as what foods we consume. In East
Asian countries, most people use chopsticks to
pick up their food. In Europe and the Americas, a variety of utensils serve different purposes. A full,
formal place setting can include a salad fork, dinner fork, dessert fork,
teaspoon, soup spoon, butter knife, and dinner knife. In other
countries, such as India and Ethiopia, many foods are picked up with
pieces of flat bread rather than utensils.
Table manners vary
widely from culture to culture. Manners include rules
about how and where people should sit, when to begin eating,
which utensils to use in certain situations and with which hand, and
what behaviors might be considered rude.
In East Asian countries, it is considered rude
to point at people with your chopsticks, or to rest
your chopsticks standing upright in your rice. In Malaysia,
eating with your left hand is considered unclean. In Japan, it is acceptable
and even encouraged to make slurping noises while eating hot noodles, but not
while eating soup. In Russia, it is considered polite to leave a bit
of food after eating, but in Brazil, people are expected to eat
everything on their plates.
Cuisine
Food and food preparation
associated with a specific region are known as that
region’s cuisine. Cuisine can be national, such as the fresh
fish and noodles associated with Japanese food. Cuisine can also
be regional or local. California cuisine,
for instance, is known for mixing different types of national cuisines,
such as French and Chinese.
A food’s adaptability to a specific region
can define that region. Maize, native to North and Central America, is
considered one of Mexico’s greatest “national treasures.” An image of Xochipilli, the Aztec god
of maize, appears on Mexico's 100-peso bill.
Most cuisines feature
staple foods of the region. In the Democratic Republic of Congo,
boiled cassava root is a staple food. The large leaves of
the cassava and a fiery pepper sauce called pili-pili are often part
of a traditional Congolese meal. Fresh-picked bananas, papayas, and pineapples
are frequently eaten. Animal proteins from poultry, fish, and
crocodiles are also popular foods in the Democratic Republic of
Congo.
Climate can also impact
the cuisine of a region. Much of Russia faces cold winters, so
few crops grow there. Warm soups are a large part of
Russian cuisine. Borscht, or beet
soup, is probably the most familiar Russian soup. Beets
are vegetables that are capable of growing in the cold, hard
ground. Grains that grow well in cold climates are also
popular in Russian cuisine. Kasha,
for example, is cooked grains, such as buckwheat, barley,
or semolina. Blini, or buckwheat pancakes, are served
with caviar, smoked fish, butter, and sour cream. Pickles, cucumbers, and onions are widely eaten.
Since Japan is surrounded by the ocean, fish is
a mainstay of
Japanese cuisine. It is prepared in a variety of ways. Sashimi, for example, is raw fish dipped in
seasoned soy sauce. Tempura is prawns or slices of fish
and vegetables dipped in batter and fried. Most sushi is made from
flavored rice covered with slices of raw or cooked fish
and vegetables.
Even non-native foods can define a region.
Potatoes were introduced to Ireland in the early 17th century, probably by
the explorer Sir Walter Raleigh, who
brought the tubers home with him after exploring the Americas.
Potatoes, especially the “lumper” variety,
grow well in cold climates and rocky soil. Within 200 years, the
population of Ireland was dependent on lumpers for most of
their carbohydrates. A potato disease, or blight, struck Ireland in the
mid-19th century, causing the so-called Irish
Potato Famine. More than a million Irish people died
of malnutrition, and a million more were forced to immigrate.
Often, cuisine reflects a country or
region’s history. Pho, for instance, is
a Vietnamese noodle soup made with large chunks of meat, vegetables,
and spices, such as basil. Vietnam was a French colony from the 19th century to the
middle of the 20th century. French colonists brought
French cuisine with them, including the stew called pot au feu. Pho is an adaptation
of pot au feu, with the most significant addition
being rice noodles, which are native to Southeast Asia. “Pho” even
sounds like “feu.”
The growing number of immigrants in many cities
has broadened people’s tastes in food. Many foods associated
with national cuisines are inventions of immigrants. Chicken tikka masala, for example, is one of the
most popular “Indian” dishes in the world. Chicken tikka masala was
invented by an immigrant Pakistani chef in
Glasgow, Scotland.
Often, immigrants will adapt their
traditional diet with foods not available in their
homeland. Chinese-American food, for instance, often features tomatoes and
potatoes, foods that are not native to Asia.
Cuisine varies widely, even within a
specific region and a specific food. In the Carolinas region of the United States, for
example, there are more than a dozen types of traditional barbecue. In this
region, pork is the most familiar barbecued meat, although
chicken and beef are also barbecued. Some barbecues feature a mustard-based
sauce, while others feature tomato, vinegar, or molasses. Still other traditional barbecues are
“dry,” and feature spice-based rubs instead of sauce.
World Food Supply
Feeding the world population requires a massive
supply of food. Since the late 1940s, grain supplies have fluctuated, but worldwide there has been a surplus, or more than enough food to feed
everyone. Yet millions go hungry. Of the over seven billion people on Earth,
more than one billion are undernourished,
according to the United Nations Food and
Agriculture Organization (FAO). Each year,
poor nutrition plays a role in about half of deaths of children under
five years old.
Why do so many people starve when the world produces
enough food to feed everyone? One reason is that resources, such as
farmland and money, are not evenly distributed among the world’s
people.
Many developed countries have millions of acres
of fertile land. This huge
agricultural economy allows nations like Canada, the United States, and
Australia to have a strong food supply for consumption as well
as export of grain, livestock, and produce.
Most hunger is not the result of a
lack of fertile land, however. Most hunger is the result
of poverty. Many people in developing
countries are too poor to grow or buy the food they need.
Crisis situations contribute
to hunger and starvation. Severe droughts, floods, and
other natural disasters can
create famines. In many developing counties, especially in sub-Saharan Africa, the population is
growing faster than the rate of food production.
In some countries, years of
continuous war have severely disrupted food production.
During conflicts, millions of people flee their
homes, often leaving crops to rot in the fields. The
region’s uncertainty and fear mean fewer crops are planted
and cultivated.
Food
Aid
These natural and manmade crises can lead millions
of people to become dependent on
international food aid. Food aid, usually in the form
of grain and other starches, is distributed to either
the government or local communities. Food aid can also mean
money for people or governments to buy their own food.
Food aid is controversial, for both recipients and donors. Some receiving countries are not allowed as
much independence as they would like. Sometimes, food aid comes
with restrictions or rules that
might have little to do with food.
The governments of countries
donating food may disagree with the politics or
decisions of the country receiving
the food aid. Food aid may be reduced if the donating
country disagrees with the receiving country’s politics, such as nuclear weapons development.
Scientists debate the relationship between economic security and food security. Food security is the
access a person, family, or community has to healthy foods.
Growing food to export may increase a
nation’s food security if the exports bring in more
money to buy food imported from elsewhere in the country or
abroad. However, access to food may be reduced, and the nation may
become dependent on foreign food sources.
To help solve the problem of hunger and
increase local food production, farmers in many developing
countries need economic assistance in acquiring new agricultural technology, such as tractors. Small-scale farmers may also
benefit from healthy draft animals, such
as water buffalo or oxen, which are used to operate machinery, such as plows.
Agricultural technology also includes
improved varieties of seeds. Seeds may withstand longer periods
of drought or flood, or they may resist disease.
Better transportation, communications systems, and storage facilities
can help improve food distribution.
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