HUMAN NUTRITION BY E.J
Human nutrition is the provision to
obtain the essential
nutrientsnecessary to support life and health. In general,
people can survive for two to eight weeks without
food, depending on stored body fat and muscle mass.[citation needed]
Poor
nutrition is a chronic problem linked to poverty, poor nutrition understanding
and practices, and deficient sanitation and food security.[1]Malnutrition
globally provides many challenges to individuals and societies. Lack of proper
nutrition contributes to worse class performance, lower test scores, and
eventually less successful students and a less productive and competitive
economy.[2] Malnutrition
and its consequences are immense contributors to deaths and disabilities
worldwide.[2] Promoting
good nutrition helps children grow, promotes human development and advances
economic growth and eradication of poverty.[1]
Content
o
2.2 Fat
The human body contains chemical
compounds, such as water,carbohydrates (sugar,
starch, and fiber), amino acids (in proteins), fatty acids (in lipids), and nucleic acids (DNA and RNA). These compounds in turn consist of elements such
as carbon, hydrogen, oxygen, nitrogen,phosphorus, calcium, iron, zinc, magnesium, manganese, and so
on. All of these chemical compounds and elements occur in various forms and
combinations (e.g. hormones, vitamins, phospholipids, hydroxyapatite),
both in the human body and
in the organisms that humans eat.
Studies
of nutritional status must take into account the state of the body before and
after experiments, as well as the chemical composition
of the whole diet and of all material excreted and
eliminated from the body (inurine and
feces). Comparing the food to the waste can help determine the specific
compounds and elements absorbed and metabolized in the body. The effects of
nutrients may only be discernible over an extended period, during which all
food and waste must be analyzed. The number of variablesinvolved in such experiments is
high, making nutritional studies time-consuming and expensive, which explains
why the science of human nutrition is still slowly evolving.
There
are seven major classes of nutrients: carbohydrates, fats, dietary fiber, minerals, proteins, vitamins, and water.
These
nutrient classes can be categorized as either macronutrients(needed
in relatively large amounts) or micronutrients (needed
in smaller quantities). The macronutrients are carbohydrates, fats, fiber,
proteins, and water. The micronutrients are minerals and vitamins.
The
macronutrients (excluding fiber and water) provide structural material (amino
acids from which proteins are built, and lipids from which cell membranes and
some signaling molecules are built), and energy. Some of the
structural material can be used to generate energy internally, and in either
case it is measured Joules or kilocalories (often
called "Calories" and written with a capital C to
distinguish them from little 'c' calories). Carbohydrates and proteins provide
17 kJ approximately (4 kcal) of energy per gram, while fats provide
37 kJ (9 kcal) per gram,[3] though
the net energy from either depends on such factors as absorption and digestive
effort, which vary substantially from instance to instance. Vitamins, minerals,
fiber, and water do not provide energy, but are required for other reasons. A
third class of dietary material, fiber (i.e., non-digestible material such as
cellulose), seems also to be required, for both mechanical and biochemical
reasons, though the exact reasons remain unclear.
Molecules
of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms.
Carbohydrates range from simple monosaccharides(glucose,
fructose, galactose) to complex polysaccharides (starch).
Fats aretriglycerides, made
of assorted fatty acid monomers bound
to a glycerolbackbone.
Some fatty acids, but not all, are essential in
the diet: they cannot be synthesized in the body. Protein molecules contain
nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental
components of protein are nitrogen-containing amino acids, some of
which are essential in
the sense that humans cannot make them internally. Some of the amino acids are
convertible (with the expenditure of energy) to glucose and can be used for
energy production just as ordinary glucose. By breaking down existing protein,
some glucose can be produced internally; the remaining amino acids are
discarded, primarily as urea in urine. This occurs naturally when atrophy takes
place, or during periods of starvation.
Other
micronutrients include antioxidants and phytochemicals which
are said to influence (or protect) some body systems. Their necessity is not as
well established as in the case of, for instance, vitamins.
Most
foods contain a mix of some or all of the nutrient classes, together with other
substances. Some nutrients can be stored internally (e.g., the fat soluble
vitamins), while others are required more or less continuously. Poor health can
be caused by a lack of required nutrients or, in extreme cases, too much of a
required nutrient. For example, both salt and water (both absolutely required)
will cause illness or even death in too large amounts.
Carbohydrates
may be classified asmonosaccharides, disaccharides, orpolysaccharides depending
on the number of monomer (sugar) units they contain. They constitute a large
part of foods such as rice, noodles, bread, and other grain-based products.
Monosaccharides
contain one sugar unit, disaccharides two, and polysaccharides three or more.
Polysaccharides are often referred to as complex carbohydrates
because they are typically long multiple branched chains of sugar units. The
difference is that complex carbohydrates take longer to digest and absorb since
their sugar units must be separated from the chain before absorption. The spike
in blood glucose levels after ingestion of simple sugars is thought to be
related to some of the heart and vascular diseases which have become more
frequent in recent times. Simple sugars form a greater part of modern diets
than formerly, perhaps leading to more cardiovascular disease. The degree of
causation is still not clear, however.
Simple
carbohydrates are absorbed quickly, and therefore raise blood-sugar levels more
rapidly than other nutrients. However, the most important plant carbohydrate
nutrient, starch, varies in its absorption. Gelatinized starch (starch heated
for a few minutes in the presence of water) is far more digestible than plain
starch. And starch which has been divided into fine particles is also more
absorbable during digestion. The increased effort and decreased availability
reduces the available energy from starchy foods substantially and can be seen
experimentally in rats and anecdotally in humans. Additionally, up to a third
of dietary starch may be unavailable due to mechanical or chemical difficulty.
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This
article duplicates, in
whole or part, the scope of other articles, specifically,Animal nutrition#Fat. Please discuss this
issue on the talk page and conform with Wikipedia's
Manual of Style by replacing the section with a link and
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the repeated material, or by spinning off the repeated text into an article
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A
molecule of dietary fat typically consists of several fatty acids (containing
long chains of carbon and hydrogen atoms), bonded to a glycerol. They are
typically found as triglycerides (three
fatty acids attached to one glycerol backbone). Fats may be classified as saturated or unsaturated depending
on the detailed structure of the fatty acids involved.[citation needed] Saturated
fats have all of the carbon atoms in their fatty acid chains bonded to hydrogen
atoms, whereas unsaturated fats have some of these carbon atoms double-bonded, so
their molecules have relatively fewer hydrogen atoms than a saturated fatty
acid of the same length. Unsaturated fats may be further classified as
monounsaturated (one double-bond) or polyunsaturated (many double-bonds).
Furthermore, depending on the location of the double-bond in the fatty acid
chain, unsaturated fatty acids are classified as omega-3 or omega-6 fatty
acids. Trans fats are
a type of unsaturated fat with trans-isomer
bonds; these are rare in nature and in foods from natural sources; they are
typically created in an industrial process called (partial) hydrogenation.
Many
studies have shown that unsaturated fats, particularly monounsaturated fats,
are best in the human diet. Saturated fats, typically from animal sources, are
next, while trans fats are to be avoided. Saturated and some trans fats are
typically solid at room temperature (such as butteror lard), while unsaturated fats are typically
liquids (such as olive oil orflaxseed oil). Trans
fats are very rare in nature, but have properties useful in the food processing industry,
such as rancidity resistance.[citation needed]
Most
fatty acids are non-essential, meaning the body can produce them as needed,
generally from other fatty acids and always by expending energy to do so.
However, in humans at least two fatty acids are essential and
must be included in the diet. An appropriate balance of essential fatty acids –omega-3 and omega-6 fatty
acids – seems also important for health, though definitive experimental
demonstration has been elusive. Both of these "omega" long-chain polyunsaturated fatty acids are substrates for
a class ofeicosanoids known
as prostaglandins,
which have roles throughout the human body. They are hormones, in some
respects. The omega-3eicosapentaenoic acid (EPA),
which can be made in the human body from the omega-3 essential fatty acid alpha-linolenic
acid (LNA),
or taken in through marine food sources, serves as a building block for series
3 prostaglandins (e.g. weakly inflammatory PGE3).
The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as a building block for
series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas arachidonic acid
(AA) serves as a building block for series 2 prostaglandins (e.g.,
pro-inflammatory PGE 2). Both DGLA and AA can be made from the omega-6linoleic acid (LA)
in the human body, or can be taken in directly through food. An appropriately
balanced intake of omega-3 and omega-6 partly determines the relative
production of different prostaglandins: one reason a balance between omega-3
and omega-6 is believed important for cardiovascular health. In industrialized
societies, people typically consume large amounts of processed vegetable oils,
which have reduced amounts of the essential fatty acids along with too much of
omega-6 fatty acids relative to omega-3 fatty acids.
Dietary
fiber is a carbohydrate (or
a polysaccharide) that is incompletely absorbed in humans and in some animals.
Like all carbohydrates, when it is metabolized it can produce four calories
(kilocalories) of energy per gram. But in most circumstances it accounts for
less than that because of its limited absorption and digestibility. There are
two subcategories: insoluble and soluble fiber. Insoluble dietary fiber
consists mainly of cellulose, a large
carbohydrate polymer that is indigestible by humans who do not have the
required enzymes to disassemble it nor do their digestive systems harbor
sufficient quantities of the types of microbes that can do so either. Soluble
dietary fiber comprises a variety of oligosaccharides, waxes, esters, resistant starches and other
carbohydrates that dissolve or gelatinize in water. Many of these soluble
fibers can be fermented or partially fermented by microbes in the human
digestive system to produce short-chain fatty acids which
are absorbed and therefore introduce some caloric content.
Whole
grains, beans and other legumes, fruits
(especially plums, prunes, and figs), and vegetables are good sources of
dietary fiber. Fiber is important to digestive health and is thought to reduce
the risk of colon cancer.[citation needed] For
mechanical reasons it can help in alleviating bothconstipation and diarrhea. Fiber
provides bulk to the intestinal contents, and insoluble fiber especially
stimulates peristalsis –
the rhythmic muscular contractions of the intestines which move digesta along
the digestive tract. Some soluble fibers produce a solution of high viscosity; this is
essentially a gel, which slows the movement of food through the intestines.
Additionally, fiber, perhaps especially that from whole grains, may help lessen
insulin spikes and reduce the risk of type 2 diabetes.[citation needed]
Proteins
are the basis of many animal body structures (e.g. muscles, skin, and hair) and
form the enyzmes which
catalyse chemical reactions throughout the body. Each protein molecule is
composed of amino acidswhich
contain nitrogen and sometimes sulphur (these components are responsible for
the distinctive smell of burning protein, such as the keratin in hair). The
body requires amino acids to produce new proteins (protein retention) and to replace
damaged proteins (maintenance). Amino acids are soluble in the digestive juices
within the small intestine, where they are absorbed into the blood. Once
absorbed they cannot be stored in the body, so they are either metabolized as
required or excreted in the urine.
Proteins
consist of amino acids in different proportions. The most important aspect and
defining characteristic of protein from a nutritional standpoint is its amino acid composition.[4] Amino
acids which an animal cannot synthesize on its own from smaller molecules are
deemed essential proteins. The synthesis of some
amino acids can be limited under special pathophysiological conditions, such as
prematurity in the infant or individuals in severe catabolic distress, and they
are called 'conditionally essential'.[4] Foods
containing protein can be rated on their relative content of amino acids, for
instance by Protein Digestibility Corrected
Amino Acid Score and biological value.
It
is a common misconception that a vegetarian diet
will be insufficient in essential proteins; both vegetarians and vegans of
any age and gender, with a healthy diet, can flourish throughout all stages of
life, although the latter group typically need to pay more attention to their
nutrition than the former. See protein combining for
more info.
Dietary
minerals are the chemical elements required
by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen that
are present in nearly all organic molecules.
The term "mineral" is archaic, since the intent is to describe simply
the less common elements in the diet. Some are heavier than the four just
mentioned – including several metals, which often occur as ions in the body.
Some dietitians recommend that these be supplied from foods in which they occur
naturally, or at least as complex compounds, or sometimes even from natural
inorganic sources (such as calcium carbonate from
ground oyster shells).
Some are absorbed much more readily in the ionic forms found in such sources.
On the other hand, minerals are often artificially added to the diet as supplements;
the most famous is likely iodine in iodized salt which
prevents goiter.
·
Magnesium, required
for processing ATP and
related reactions (builds bone, causes strong peristalsis, increases
flexibility, increases alkalinity). Approximately 50% is in bone, the remaining
50% is almost all inside body cells, with only about 1% located in
extracellular fluid. Food sources include oats, buckwheat, tofu, nuts, caviar,
green leafy vegetables, legumes, and chocolate.[5][6]
·
Phosphorus, required
component of bones; essential for energy processing[7] Approximately
80% is found in inorganic portion of bones and teeth. Phosphorus is a component
of every cell, as well as important metabolites, including DNA, RNA, ATP, and
phospholipids. Also important in pH regulation. Food sources include cheese,
egg yolk, milk, meat, fish, poultry, whole-grain cereals, and many others.[5]
·
Potassium, a very
common electrolyte (heart and nerve health). With sodium, potassium is involved
in maintaining normal water balance, osmotic equilibrium, and acid-base
balance. In addition to calcium, it is important in the regulation of
neuromuscular activity. Food sources include bananas, avocados, vegetables,
potatoes, legumes, and mushrooms.[6]
·
Sodium, a very common electrolyte; not
generally found in dietary supplements, despite being needed in large
quantities, because the ion is very common in food: typically as sodium chloride, or
common salt
Many
elements are required in smaller amounts (microgram quantities), usually
because they play a catalytic role
in enzymes.[8] Some
trace mineral elements (RDA < 200 mg/day) are, in alphabetical order:
·
Iodine required
not only for the biosynthesis of thyroxin, but
probably, for other important organs as breast, stomach, salivary glands,
thymus etc. (see Extrathyroidal iodine); for this reason iodine is needed in
larger quantities than others in this list, and sometimes classified with the
macrominerals
·
Zinc required
for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase, carbonic
anhydrase
As
with the minerals discussed above, some vitamins are recognized as essential
nutrients, necessary in the diet for good health. (Vitamin D is
the exception: it can alternatively be synthesized in the skin, in the presence
ofUVB radiation.)
Certain vitamin-like compounds that are recommended in the diet, such as carnitine, are
thought useful for survival and health, but these are not "essential"
dietary nutrients because the human body has some capacity to produce them from
other compounds. Moreover, thousands of different phytochemicals have
recently been discovered in food (particularly in fresh vegetables), which may
have desirable properties including antioxidant activity
(see below); experimental demonstration has been suggestive but inconclusive.
Other essential nutrients not classed as vitamins include essential
amino acids (see above), essential
fatty acids(see above), and the
minerals discussed in the preceding section.
Vitamin
deficiencies may result in disease conditions: goiter, scurvy,osteoporosis,
impaired immune system,
disorders of cell metabolism, certain
forms of cancer, symptoms of premature aging, and poor psychological health (including eating disorders),
among many others.[9] Excess
of some vitamins is also dangerous to health (notably vitamin A), and for
at least one vitamin, B6, toxicity begins at levels not far above the required
amount. Deficiency or excess of minerals can also have serious health consequences.
For
those who have healthy kidneys, it is somewhat difficult to drink too much
water,[citation needed] but
(especially in warm humid weather and while exercising) it is dangerous to
drink too little. People can drink far more water than necessary while
exercising, however, putting them at risk of water
intoxication, which can be fatal. In particular, large amounts of
de-ionized water are dangerous.
There
is research interest in the health effects of phytochemicals, but to date there
is no conclusive evidence.[10] While
many fruits and vegetables which happen to contain phytochemicals are thought
to be components of a healthy diet, by comparison dietary supplements based on
them have no proven health benefit.[10]
Individuals
with highly active lifestyles require more nutrients.
Protein milkshakes, made from protein
powder (center) and milk (left), are a common bodybuilding supplement.
Protein
is an important component of every cell in the body. Hair and nails are mostly
made of protein. The body uses protein to build and repair tissues. Also
protein is used to make enzymes, hormones, and other body chemicals. Protein is
an important building block of bones, muscles, cartilage, skin, and blood.
The
protein requirement for each individual differs, as do opinions about whether
and to what extent physically active people require more protein. The 2005Recommended Dietary Allowances(RDA), aimed at the
general healthy adult population, provide for an intake of 0.8 – 1 grams
of protein per kilogram of body weight (according to the BMI formula), with the
review panel stating that "no additional dietary protein is suggested for
healthy adults undertaking resistance or endurance exercise".[11]
Water
is one of the most important nutrients in the sports diet. It helps eliminate
food waste products in the body, regulates body temperature during activity and
helps with digestion. Maintaining hydration during periods of physical exertion
is key to peak performance. While drinking too much water during activities can
lead to physical discomfort, dehydration in excess of 2% of body mass (by
weight) markedly hinders athletic performance.[12] Water
and salt dosage is based on work performed, lean body mass, and environmental
factors, especially ambient temperature and humidity. Maintaining the right
amount is key.
Additional
carbohydrates and protein taken before, during, and after exercise will improve
endurance (increase time to exhaustion) as well as speed recovery as long as
the exercise is compatible with digestion of the substance taken, e.g. a steak
eaten while running a marathon may not be fully digested and may hinder
performance.
The
main fuel used by the body during exercise is carbohydrates, which is stored in
muscle as glycogen – a form of sugar. During exercise, muscle glycogen reserves
can be used up, especially when activities last longer than 90 min.[citation needed] Because
the amount of glycogen stored in the body is limited, it is important for
athletes to replace glycogen by consuming a diet high in carbohydrates. Meeting
energy needs can help improve performance during the sport, as well as improve
overall strength and endurance.
There
are different kinds of carbohydrates: simple (for example from fruits) and
complex (for example from grains such as wheat). Simple sugars can be from an
unrefined natural source, or may be refined and added to processed food. A
typical American consumes about 50% of their carbohydrates as refined sugars.
Over the course of a year, the average American consumes 204 litres (54
US gallons @ 3.78l per gallon) of soft drinks, which contain the highest amount
of added sugars.[13] Even
though carbohydrates are necessary for humans to function, they are not all
equally healthful. When machinery has been used to remove bits of high fiber,
the carbohydrates are refined. These are the carbohydrates found in white bread
and fast food.[14]
Malnutrition
refers to insufficient, excessive, or imbalanced consumption of nutrients. In
developed countries, the diseases of malnutrition are most often associated
with nutritional imbalances or excessive consumption. Although there are more
people in the world who are malnourished due to excessive consumption,
according to the United Nations World Health Organization, the real challenge in
developing nations today, more than starvation, is combating insufficient
nutrition – the lack of nutrients necessary for the growth and maintenance of
vital functions.
The
causes of malnutrition are directly linked to inadequate macronutrient
consumption and disease, and are indirectly linked to factors like “household
food security, maternal and child care, health services, and the environment.” [2]
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Nutrients
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Deficiency
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Excess
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none
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none
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none
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none
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malabsorption of
fat-soluble vitamins, rabbit
starvation (if protein intake is high), during development: stunted brain
development and reduced brain weight.[17]
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bleeding, hemorrhages
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none
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hypervitaminosis
A(cirrhosis, hair loss)
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cracking of skin and
corneal unclearation
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pernicious anemia
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hypervitaminosis
D(dehydration, vomiting, constipation)
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nervous disorders
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hypervitaminosis
E(anticoagulant: excessive bleeding)
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weakness, nausea,
vomiting, impaired breathing, andhypotension
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Research
indicates that improving the awareness of nutritious meal choices and
establishing long-term habits of healthy eating has a positive effect on a
cognitive and spatial memory capacity, potentially increasing a student's
potential to process and retain academic information.[citation needed]
Some
organizations have begun working with teachers, policymakers, and managed
foodservice contractors to mandate improved nutritional content and increased
nutritional resources in school cafeterias from primary to university level
institutions. Health and nutrition have been proven to have close links with
overall educational success.[19] Currently
less than 10% of American college students report that they eat the recommended
five servings of fruit and vegetables daily.[20] Better
nutrition has been shown to have an impact on both cognitive and spatial memory
performance; a study showed those with higher blood sugar levels performed
better on certain memory tests.[21] In
another study, those who consumed yogurt performed better on thinking tasks
when compared to those who consumed caffeine free diet soda or confections.[22] Nutritional
deficiencies have been shown to have a negative effect on learning behavior in mice
as far back as 1951.[23]
"Better
learning performance is associated with diet induced effects on learning and
memory ability".[24]
The
"nutrition-learning nexus" demonstrates the correlation between diet
and learning and has application in a higher education setting.
"We
find that better nourished children perform significantly better in school, partly
because they enter school earlier and thus have more time to learn but mostly
because of greater learning productivity per year of schooling."[25]
91%
of college students feel that they are in good health while only 7% eat their
recommended daily allowance of fruits and vegetables.[20]
More
"engaged" learning models that encompass nutrition is an idea that is
picking up steam at all levels of the learning cycle.[27]
Nutritional
supplement treatment may be appropriate for major depression,bipolar disorder, schizophrenia, and obsessive compulsive disorder, the four most common
mental disorders in developed countries.[28]Supplements
that have been studied most for mood elevation and stabilization include eicosapentaenoic acid and docosahexaenoic
acid(each of which are an omega-3
fatty acid contained
in fish oil, but not inflaxseed oil), vitamin B12, folic acid, and inositol.
Cancer
has become common in developing countries. According to a study by the International Agency for Research on Cancer,
"In the developing world, cancers of the liver, stomach and esophagus were
more common, often linked to consumption of carcinogenic preserved foods, such
as smoked or salted food, and parasitic infections that attack organs."
Lung cancer rates are rising rapidly in poorer nations because of increased use
of tobacco. Developed countries "tended to have cancers linked to
affluence or a 'Western lifestyle' – cancers of the colon, rectum, breast and
prostate – that can be caused by obesity, lack of exercise, diet and age."[29]
A
comprehensive worldwide report, "Food, Nutrition, Physical
Activity and the Prevention of Cancer: a Global Perspective",
compiled by the World Cancer Research Fund and
the American Institute for Cancer Research,
reports that there is a significant relation between lifestyle (including food
consumption) and cancer prevention.
The same report recommends eating mostly foods of plant origin and aiming to
meet nutritional needs through
diet alone, while limiting consumption of energy-dense foods, red meat,alcoholic drinks and salt and
avoiding sugary drinks, processed meat and
moldy cereals (grains)
or pulses (legumes).
Protein
consumption leads to an increase in IGF-1 which
plays a role in cancer development. See IGF-1#Cancer.
Several
lines of evidence indicate lifestyle-induced hyperinsulinemia and
reduced insulin function (i.e. insulin
resistance) as decisive factors in many disease states. For example,
hyperinsulinemia and insulin resistance are strongly linked to chronic
inflammation, which in turn is strongly linked to a variety of adverse
developments such as arterial microinjuries and clotformation (i.e. heart disease) and
exaggerated cell division (i.e. cancer).[30]Hyperinsulinemia
and insulin resistance (the so-called metabolic
syndrome) are characterized by a combination of abdominal obesity, elevated blood sugar,
elevated blood pressure,
elevated blood triglycerides, and
reduced HDL cholesterol.
Obesity
can unfavourably alter hormonal and metabolic status via resistance to the
hormone leptin, and a vicious cycle may occur in which
insulin/leptin resistance
and obesity aggravate one another. The vicious cycle is putatively fuelled by
continuously high insulin/leptin stimulation and fat storage, as a result of
high intake of strongly insulin/leptin stimulating foods and energy. Both
insulin and leptin normally function as satiety signals to the hypothalamus in
the brain; however, insulin/leptin resistance may reduce this signal and
therefore allow continued overfeeding despite large body fat stores.
There
is a debate about how and to what extent different dietary factors – such as
intake of processed carbohydrates, total protein, fat, and carbohydrate intake,
intake of saturated and trans fatty acids, and low intake of vitamins/minerals
– contribute to the development of insulin and leptin resistance. Evidence
indicates that diets possibly protective against metabolic syndrome include low
saturated and trans fat intake
and foods rich in dietary fiber, such
as high consumption of fruits and vegetables and moderate intake of low-fat
dairy products.[31]
Excess
water intake, without replenishment of sodium and potassium salts, leads to hyponatremia, which
can further lead to water
intoxication at
more dangerous levels. A well-publicized case occurred in 2007, when Jennifer Strange died
while participating in a water-drinking contest.[32] More
usually, the condition occurs in long-distance endurance events (such as marathonor triathlon competition
and training) and causes gradual mental dulling, headache, drowsiness,
weakness, and confusion; extreme cases may result in coma, convulsions, and
death. The primary damage comes from swelling of the brain, caused by increased
osmosis as blood salinity decreases. Effective fluid replacement techniques
include Water aid stations during running/cycling races, trainers providing
water during team games such as Soccer and devices such as Camel Baks which can
provide water for a person without making it too hard to drink the water.
The
most common non-infectious diseases worldwide, that contribute most to the
global mortality rate, are cardiovascular diseases, various cancers, diabetes,
and chronic respiratory problems, all of which are linked to poor nutrition.
Nutrition and diet are closely associated with the leading causes of death,
including cardiovascular disease and cancer. Obesity and high sodium intake can
contribute to ischemic heart disease, while consumption of fruits and
vegetables can decrease the risk of developing cancer.[33]
The
connection between food and sickness is well-established- foodborne and
infectious diseases can result in malnutrition, and malnutrition exacerbates
infectious disease. Poor nutrition leaves children and adults more susceptible
to contracting life-threatening diseases such as diarrheal infections and
respiratory infections.[1] According
to the WHO, in 2011, 6.9 million children died of infectious diseases like
pneumonia, diarrhea, malaria, and neonatal conditions, of which at least one
third were associated with undernutrition.[34][35][36]
According
to UNICEF, in 2011, 101 million children across the globe were underweight and
one in four children, 165 million, were stunted in growth.[37]Simultaneously,
there are 43 million children under five who are overweight or obese.[2] Nearly
20 million children under 5 suffer from severe acute malnutrition, a
life-threatening condition requiring urgent treatment.[2]According
to estimations at UNICEF, hunger will
be responsible for 5.6 million deaths of children under the age of five this
year.[1] These
all represent significant public health emergencies.[33] This
is because proper maternal and child nutrition has immense consequences for
survival, acute and chronic disease incidence, normal growth, and economic
productivity of individuals.[38]
Childhood malnutrition is
common and contributes to the global burden of disease.[39] Childhood
is a particularly important time to achieve good nutrition status, because poor
nutrition has the capability to lock a child in a vicious cycle of disease
susceptibility and recurring sickness, which threatens cognitive and social
development.[1] Undernutrition
and bias in access to food and health services leaves children less likely to
attend or perform well in school.[1]
UNICEF
defines under nutrition “as the outcome of insufficient food intake (hunger)
and repeated infectious diseases. Under nutrition includes being underweight
for one’s age, too short for one’s age (stunted), dangerously thin (wasted),
and deficient in vitamins and minerals (micronutrient malnutrient).[1] Under
nutrition causes 53% of deaths of children under five across the world.[1] It
has been estimated that undernutrition is the underlying cause for 35% of child
deaths.[40] The
Maternal and Child Nutrition Study Group estimate that under nutrition,
“including fetal growth restriction, stunting, wasting, deficiencies of vitamin
A and zinc along with suboptimum breastfeeding- is a cause of 3.1 million child
deaths and infant mortality, or 45% of all child deaths in 2011”.[38]
When
humans are undernourished, they no longer maintain normal bodily functions,
such as growth, resistance to infection, or have satisfactory performance in
school or work.[1] Major
causes of under nutrition in young children include lack of proper breast
feeding for infants and illnesses such as diarrhea, pneumonia, malaria, and
HIV/AIDS.[1] According
to UNICEF 146 million children across the globe, that one out of four under the
age of five, are underweight.[1] The
amount of underweight children has decreased since 1990, from 33 percent to 28
percent between 1990 and 2004.[1]Underweight
and stunted children are more susceptible to infection, more likely to fall
behind in school, more likely to become overweight and develop non-infectious
diseases, and ultimately earn less than their non-stunted coworkers.[41] Therefore,
undernutrition can accumulate deficiencies in health which results in less
productive individuals and societies [1]
Many
children are born with the inherent disadvantage of low birth weight, often
caused by intrauterine growth restriction and poor maternal nutrition, which
results in worse growth, development, and health throughout the course of their
lifetime.[33] Children
born at low birthweight (less than 5.5 pounds), are less likely to be healthy
and are more susceptible to disease and early death.[1] Those
born at low birthweight also are likely to have a depressed immune system,
which can increase their chances of heart disease and diabetes later on in
life.[1] Because
96% of low birthweight occurs in the developing world, low birthweight is
associated with being born to a mother in poverty with poor nutritional status
that has had to perform demanding labor.[1]
Stunting
and other forms of undernutrition reduces a child’s chance of survival and
hinders their optimal growth and health.[41] Stunting
has demonstrated association with poor brain development, which negatively
impacts cognitive ability, academic performance, and eventually earning
potential.[41] Important
determinants of stunting include the quality and frequency of infant and child
feeding, infectious disease susceptibility, and the mother’s nutrition and
health status.[41] Undernourished
mothers are more likely to birth stunted children, perpetuating a cycle of
undernutrition and poverty.[41] Stunted
children are more likely to develop obesity and chronic diseases upon reaching
adulthood.[41] Therefore,
malnutrition resulting in stunting can further worsen the obesity epidemic,
especially in low and middle income countries.[41] This
creates even new economic and social challenges for vulnerable impoverished
groups.[41]
Malnutrition
in industrialized nations is primarily due to excess calories and
non-nutritious carbohydrates, which has contributed to the obesity epidemic
affecting both developed and some developing nations.[42] In
2008, 35% of adults above the age of 20 years old were overweight (BMI
25 kg/m), a prevalence that has doubled worldwide between 1980 and 2008.[43] Also
10% of men and 14% of women were obese, with an BMI greater than 30.[44] Rates
of overweight and obesity vary across the globe, with the highest prevalence in
the Americas, followed by European nations, where over 50% of the population is
overweight or obese.[44]
Obesity
is more prevalent amongst high income and higher middle income groups than
lower divisions of income.[44] Women
are more likely than men to be obese, where the rate of obesity in women
doubled from 8% to 14% between 1980 and 2008.[44] Being
overweight as a child has become an increasingly important indicator for later
development of obesity and non-infectious diseases such as heart disease.[38] In
several western European nations, the prevalence of overweight and obese
children rose by 10% from 1980 to 1990, a rate that has began to accelerate
recently.[1]
Iron deficiency is
the most common inadequate nutrient worldwide, affecting approximately 2
billion people.[45] Globally,
anemia affects 1.6 billion people, and represents a public health emergency in
children under five and mothers.[46] The
World Health Organization estimates that there exists 469 million women of
reproductive age and approximately 600 million preschool and school-age
children worldwide who are anemic.[47] Anemia,
especially iron-deficient anemia, is a critical problem for cognitive
developments in children, and its presence leads to maternal deaths and poor
brain and motor development in children.[1] The
development of anemia affects mothers and children more because infants and
children have higher iron requirements for growth.[48] Health
consequences for iron deficiency in young children include increased perinatal
mortality, delayed mental and physical development, negative behavioral
consequences, reduced auditory and visual function, and impaired physical
performance.[49] The
negative impacts of iron deficiency during child development cannot be reversed
and result in reduced academic performance, poor physical work capacity, and
decreased productivity in adulthood.[2] Mothers
are also very susceptible to iron-deficient anemia because women lose iron
during menstruation, and rarely supplement it in their diet.[2] Maternal
iron deficiency anemia increases the chances of maternal mortality,
contributing to at least 18% of maternal deaths in low and middle income
countries.[50]
Vitamin A plays
an essential role in developing the immune system in children, therefore, it is
considered an essential micronutrient that can greatly affect health.[1] However,
because of the expense of testing for deficiencies, many developing nations
have not been able to fully detect and address vitamin A deficiency, leaving
vitamin A deficiency considered a silent hunger.[1] According
to estimates, subclinical vitamin A deficiency, characterized by low retinol
levels, affects 190 million pre-school children and 19 million mothers
worldwide.[51] The
WHO estimates that 5.2 million of these children under 5 are affected by night
blindness, which is considered clinical vitamin A deficiency.[52] Severe
vitamin A deficiency (VAD) for developing children can result in visual
impairments, anemia and weakened immunity, and increase their risk of morbidity
and mortality from infectious disease.[53] This
also presents a problem for women, with WHO estimating that 9.8 million women
are affected by night blindness.[54] Clinical
vitamin A deficiency is particularly common among pregnant women, with
prevalence rates as high as 9.8% in South-East Asia.[51]
Estimates
say that 28.5% of the global population is iodine deficient, representing 1.88
billion individuals.[55] Although
salt iodization programs have reduced the prevalence of iodine deficiency, this
is still a public health concern in 32 nations. Moderate deficiencies are
common in Europe and Africa, and over consumption is common in the Americas.[33] Iodine-deficient
diets can interfere with adequate thyroid hormone production, which is
responsible for normal growth in the brain and nervous system. This ultimately
leads to poor school performance and impaired intellectual capabilities.[1]
Improvement
of breast feeding practices, like early initiation and exclusive breast feeding
for the first two years of life, could save the lives of 1.5 million children
annually.[56] Nutrition
interventions targeted at young infants aged 0–5 months first encourages early
initiation of breastfeeding.[2]Though
the relationship between early initiation of breast feeding and improved health
outcomes has not been formally established, a recent study in Ghana suggests
a causal relationship between early initiation and reduced infection-caused
neo-natal deaths.[2] Also,
experts promote exclusive breastfeeding, rather than using formula, which has
shown to promote optimal growth, development, and health of infants.[57] Exclusive
breasfeeding often indicates nutritional status because infants that consume
breast milk are more likely to receive all adequate nourishment and nutrients
that will aid their developing body and immune system. This leaves children
less likely to contract diarrheal diseases and respiratory infections.[1]
Besides
the quality and frequency of breastfeeding, the nutritional status of mothers
affects infant health. When mothers do not receive proper nutrition, it
threatens the wellness and potential of their children.[1] Well-nourished
women are less likely to experience risks of birth and are more likely to
deliver children who will develop well physically and mentally.[1] Maternal
undernutrition increases the chances of low-birth weight, which can increase
the risk of infections and asphyxia in fetuses, increasing the probability of
neonatal deaths.[58] Growth
failure during intrauterine conditions, associated with improper mother
nutrition, can contribute to lifelong health complications.[2] Approximately
13 million children are born with intrauterine growth restriction annually.[59]
Data
on global and regional food supply shows that consumption rose from 2011-2012
in all regions. Diets became more diverse, with a decrease in consumption of
cereals and roots and an increase in fruits, vegetables, and meat products.[60] However,
this increase masks the discrepancies between nations, where Africa, in
particular, saw a decrease in food consumption over the same years.[60] This
information is derived from food balance sheets that reflect national food
supplies, however, this does not necessarily reflect the distribution of micro
and macronutrients.[60] Often
inequality in food access leaves distribution which uneven, resulting in
undernourishment for some and obesity for others.[60]
Undernourishment,
or hunger, according to the FAO, is dietary intake below the minimum daily
energy requirement.[60] The
amount of undernourishment is calculated utilizing the average amount of food
available for consumption, the size of the population, the relative disparities
in access to the food, and the minimum calories required for each individual.[60] According
to FAO, 868 million people (12% of the global population) were undernourished
in 2012.[60] This
has decreased across the world since 1990, in all regions except for Africa,
where undernourishment has steadily increased.[60]However,
the rates of decrease are not sufficient to meet the first Millennium
Development Goal of halving hunger between 1990 and 2015.[60] The
global financial, economic, and food price crisis in 2008 drove many people to
hunger, especially women and children. The spike in food prices prevented many
people from escaping poverty, because the poor spend a larger proportion of
their income on food and farmers are net consumers of food.[61] High
food prices cause consumers to have less purchasing power and to substitute
more-nutritious foods with low-cost alternatives.[62]
According
to UNICEF, South Asia has the highest levels of underweight children under
five, followed by sub-Saharan Africans nations, with Industrialized countries
and Latin nations having the lowest rates.[1]
In
the US, dietitians are
registered (RD) or licensed (LD) with the Commission for Dietetic Registration
and the American Dietetic Association, and are only able to use the title
"dietitian," as described by the business and professions codes of
each respective state, when they have met specific educational and experiential
prerequisites and passed a national registration or licensure examination,
respectively. In California, registered dietitians must abide by the "Business and Professions Code of Section
2585-2586.8".Anyone may call
themselves a nutritionist, including unqualified dietitians, as this term is
unregulated. Some states, such as the State of Florida, have begun to include
the title "nutritionist" in state licensure requirements. Most
governments provide guidance on nutrition, and some also impose mandatory
disclosure/labeling requirements
for processed food manufacturers and restaurants to assist consumers in
complying with such guidance.
In
the US, nutritional standards and recommendations are established jointly by
the US Department of Agriculture and US Department of Health and
Human Services. Dietary and physical activity guidelines from the
USDA are presented in the concept of a plate of food which
in 2011 superseded the food pyramid that
had replaced the Four Food Groups.
The Senate committee currently responsible for oversight of the USDA is the Agriculture,
Nutrition and Forestry Committee. Committee hearings are
often televised on C-SPAN.
The U.S. Department of Health and Human Services provides
a sample week-long menu which fulfills the nutritional recommendations of the
government.[63] Canada's
Food Guide is
another governmental recommendation.
According
to UNICEF, the Commonwealth of Independent States has
the lowest rates of stunting and wasting, at 14
percent and 3 percent.[1] The
nations of Estonia, Finland, Iceland, Lithuania and Sweden have the lowest
prevalence of low birthweight children
in the world- at 4%.[1] Proper
prenatal nutrition is responsible for this small prevalence of low birthweight
infants.[1]However,
low birthweight rates are increasing, due to the use of fertility drugs,
resulting in multiple births, women bearing children at an older age, and the
advancement of technology allowing more pre-term infants to survive.[1] Industrialized
nations more often face malnutrition in the form of over-nutrition from excess
calories and non-nutritious carbohydrates, which has contributed greatly to the
public health epidemic of obesity.[42]Disparities,
according to gender, geographic location and socio-economic position, both
within and between countries, represent the biggest threat to child nutrition
in industrialized countries. These disparities are a direct product of social
inequalities and social
inequalities are
rising throughout the industrialized world, particularly in Europe.[1]
South Asia has
the highest percentage and number of underweight children under five in the
world, at approximately 78 million children.[1] Patterns
of stunting and wasting are similar, where 44% have not reached optimal height
and 15% are wasted, rates much higher than any other regions.[1]This
region of the world has extremely high rates of child underweight- 46% of its
child population under five is underweight.[1] India,
Bangladesh, and Pakistan alone account for half the globe’s underweight child
population.[1]South
Asian nations have made progress towards the MDGs, considering the rate has decreased from
53% since 1990, however, a 1.7% decrease of underweight prevalence per year
will not be sufficient to meet the 2015 goal.[1] Some
nations, such as Afghanistan, Bangladesh, and Sri Lanka, on the
other hand, have made significant improvements, all decreasing their prevalence
by half in ten years.[1] While India and Pakistan have
made modest improvements, Nepal has
made no significant improvement in underweight child prevalence.[1] Other
forms of undernutrition have continued to persist with high resistance to
improvement, such as the prevalence of stunting and wasting, which has not
changed significantly in the past 10 years.[1] Causes
of this poor nutrition include energy-insufficient diets, poor sanitation
conditions, and the gender disparities in educational and social status.[1] Girls
and women face discrimination especially in nutrition status, where South Asia
is the only region in the world where girls are more likely to be underweight
than boys.[1] In
South Asia, 60% of children in the lowest quintile are underweight, compared to
only 26% in the highest quintile, and the rate of reduction of underweight is
slower amongst the poorest.[64]
The
Eastern and Southern African nations have shown no improvement since 1990 in
the rate of underweight children under five.[1] They
have also made no progress in halving hunger by 2015, the most prevalent Millennium Development Goal.[1] This
is due primarily to the prevalence of famine, declined agricultural
productivity, food emergencies, drought, conflict, and increased poverty.[1] This,
along with HIV/AIDS,
has inhibited the nutrition development of nations such as Lesotho, Malawi, Mozambique, Swaziland,Zambia and Zimbabwe.[1] Botswana has
made remarkable achievements in reducing underweight prevalence, dropping 4% in
4 years, despite its place as the second leader in HIV prevalence amongst
adults in the globe.[1]South Africa, the
wealthiest nation in this region, has the second lowest proportion of
underweight children at 12%, but has been steadily increasing in underweight
prevalence since 1995.[1] Almost
half of Ethiopian children
are underweight, and along with Nigeria, they
account for almost one-third of the underweight under five in all of Sub-Saharan
Africa.[1]
West/Central Africa has
the highest rate of children under five underweight in the world.[1] Of
the countries in this region, the Congo has the lowest rate at 14%, while the
nations of Democratic Republic of the Congo, Ghana,Guinea, Mali, Nigeria, Senegal and Togo are
improving slowly.[1] In Gambia, rates decreased from 26% to 17% in
four years, and their coverage of vitamin A supplementation reaches 91% of
vulnerable populations.[1] This
region has the next highest proportion of wasted children, with 10% of the
population under five not at optimal weight.[1] Little
improvement has been made between the years of 1990 and 2004 in reducing the
rates of underweight children under five, whose rate stayed approximately the
same.[1] Sierra Leone has
the highest child under five mortality rate in the world, due predominantly to
its extreme infant mortality rate, at 238 deaths per 1000 live births.[1] Other
contributing factors include the high rate of low birthweight children (23%)
and low levels of exclusive breast feeding (4%).[1]Anemia
is prevalent in these nations, with unacceptable rates of iron deficient
anemia.[1] The
nutritional status of children is further indicated by its high rate of child
wasting - 10%.[1] Wasting
is a significant problem in Sahelian countries – Burkina Faso, Chad, Mali, Mauritania and Niger –
where rates fall between 11% and 19% of under fives, affecting more than 1
million children.[1]
Six
countries in the Middle East and North Africa region
are on target to meet goals for reducing underweight children by 2015, and 12
countries have prevalence rates below 10%.[1] However,
the nutrition of children in the region as a whole has degraded for the past
ten years due to the increasing portion of underweight children in three
populous nations – Iraq,Sudan, and Yemen.[1] Forty
six percent of all children in Yemen are
underweight, a percentage that has worsened by 4% since 1990.[1] In
Yemen, 53% of children under five are stunted and 32% are born at low birth
weight.[1] Sudan
has an underweight prevalence of 41%, and the highest proportion of wasted
children in the region at 16%.[1] One
percent of households in Sudan consume iodized salt.[1] Iraq
has also seen an increase in child underweight since 1990.[1] Djibouti, Jordan, the Occupied Palestinian Territory (OPT), Oman, the Syrian
Arab Republic and Tunisiaare all
projected to meet minimum nutrition goals, with OPT, Syrian AR, and Tunisia the
fastest improving regions.[1] This
region demonstrates that undernutrition does not always improve with economic
prosperity, where theUnited
Arab Emirates, for example, despite being a wealthy nation, has
similar child death rates due to malnutrition to those seen in Yemen.[1]
The East Asia/Pacific
region has reached its goals on nutrition, in part due to the improvements
contributed by China, the region’s most populous country.[1] China
has reduced its underweight prevalence from 19 percent to 8 percent between
1990 and 2002.[1] China
played the largest role in the world in decreasing the rate of children under
five underweight between 1990 and 2004, halving the prevalence.[1] This
reduction of underweight prevalence has aided in the lowering of the under 5
mortality rate from 49 to 31 of 1000. They also have a low birthweight rate at
4%, a rate comparable to industrialized countries, and over 90% of households
receive adequate iodized salts.[1] However,
large disparities exist between children in rural and urban areas, where 5
provinces in China leave 1.5 million children iodine deficient and susceptible
to diseases.[1] Singapore, Vietnam, Malaysia, andIndonesia are
all projected to reach nutrition MDGs.[1] Singapore has
the lowest under five mortality rate of any nation, besides Iceland, in the
world, at 3%.[1] Cambodia has
the highest rate of child mortality in the region (141 per 1,000 live births),
while still its proportion of underweight children increased by 5 percent to
45% in 2000. Further nutrient indicators show that only 12 per cent of
Cambodian babies are exclusively breastfed and only 14 per cent of households
consume iodized salt.[1]
This
region has undergone the fastest progress in decreasing poor nutrition status
of children in the world.[1] The Latin American region
has reduced underweight children prevalence by 3.8% every year between 1990 and
2004, with a current rate of 7% underweight.[1] They
also have the lowest rate of child mortality in the developing world, with only
31 per 1000 deaths, and the highest iodine consumption.[1] Cuba has
seen improvement from 9 to 4 percent underweight under 5 between 1996 and 2004.[1] The
prevalence has also decreased in the Dominican
Republic, Jamaica, Peru, and Chile.[1] Chile
has a rate of underweight under 5, at merely 1%.[1] The
most populous nations, Brazil and Mexico, mostly have relatively low rates of
underweight under 5, with only 6% and 8%.[1] Guatemala has
the highest percentage of underweight and stunted children in the region, with
rates above 45%.[1] There
are disparities amongst different populations in this region. For example,
children in rural areas have twice the prevalence of underweight at 13%,
compared to urban areas at 5%.[1]
In
all regions of the world, lack of proper nutrition is both a consequence and
cause of poverty.[1] Internationally,
impoverished individuals are less likely to have access to nutritious food, and
are more vulnerable to struggle harder to come out of poverty than those who
have healthy diets.[1]Disparities
in socieo-economic status, between and within nations, provide the largest
threat to child nutrition in industrialized nations, where social inequality is
on the rise.[65] According
to UNICEF, children living in the poorest households are twice as likely to be
underweight as those in the richest.[1] Those
in the lowest wealth quintile and whose mothers have the least education
demonstrate the highest rates of child mortality and stunting.[66] Throughout
the developing world, socioeconomic inequality in childhood malnutrition is
more severe than in upper income brackets, regardless of the general rate of
malnutrition.[67] Concurrently,
the greatest increase in childhood obesity has been seen in the lower middle
income bracket.[44]
According
to UNICEF, children in rural locations are more than twice as likely to be
underweight as compared to children under five in urban areas.[1] In
Latin American/Caribbean nations, “Children living in rural areas in Bolivia,
Honduras, Mexico and Nicaragua are more than twice as likely to be underweight
as children living in urban areas. That likelihood doubles to four times in
Peru.” [1]
In
the United States, the incidence of low birthweight is on the rise amongst all
populations, but particularly amongst minorities.[68]
According
to UNICEF, boys and girls have almost identical rates of underweight children
under 5 across the world, except for in South Asia.[1]
Nutrition
directly influences progress towards meeting the Millennium Goals of
eradicating hunger and poverty through health and education.[1]Therefore,
nutrition interventions take a multi-faceted approach to improve the nutrition
status of various populations. Policy and programming must target both
individual behavioral changes and policy approaches to public health. While
most nutrition interventions focus on delivery through the health-sector,
non-health sector interventions targeting agriculture, water and sanitation,
and education are important as well.[2] Global
nutrition micro-nutrient deficiencies often receive large-scale solution
approaches by deploying large governmental and non-governmental organizations.
For example, in 1990, iodine deficiency was particularly prevalent, with one in
five households, or 1.7 billion people, not consuming adequate iodine, leaving
them at risk to develop associated diseases.[1] Therefore,
a global campaign to iodize salt to eliminate iodine deficiency successfully
boosted the rate to 69% of households in the world consuming adequate amounts
of iodine.[1]
Emergencies
and crises often exacerbate undernutrition, due to the aftermath of crises that
include food insecurity, poor health resources, unhealthy environments, and
poor healthcare practices.[1] Therefore,
the repercussions of natural disasters and other emergencies can exponentially
increase the rates of macro and micronutrient deficiencies in populations.[1]Disaster
relief interventions often take a multi-faceted public health approach.
UNICEF’s programming targeting nutrition services amongst disaster settings
include nutrition assessments, measles immunization, vitamin A supplementation,
provision of fortified foods and micronutrient supplements, support for
breastfeeding and complementary feeding for infants and young children, and
therapeutic and supplementary feeding.[1]For
example, during Nigeria’s food crisis of 2005, 300,000 children received
therapeutic nutrition feeding programs through the collaboration of UNICEF, the
Niger government, the World Food Programme, and 24 NGOs utilizing community and
facility based feeding schemes.[1]
Interventions
aimed at pregnant women, infants, and children take a behavioral and
program-based approach. Behavioral intervention objectives include promoting
proper breast-feeding, the immediate initiation of breastfeeding, and its
continuation through 2 years and beyond.[2]UNICEF
recognizes that to promote these behaviors, healthful environments must be
established conducive to promoting these behaviors, like healthy hospital
environments, skilled health workers, support in the public and workplace, and
removing negative influences.[2] Finally,
other interventions include provisions of adequate micro and macro nutrients
such as iron, anemia, and vitamin A supplements and vitamin-fortified foods and
ready-to-use products.[2] Programs
addressing micro-nutrient deficiencies, such as those aimed at anemia, have
attempted to provide iron supplementation to pregnant and lactating women.
However, because supplementation often occurs too late, these programs have had
little impact.[1] Interventions
such as women’s nutrition, early and exclusive breastfeeding, appropriate
complementary food and micronutrient supplementation have proven to reduce
stunting and other manifestations of undernutrition.[41] A
Cochrane review of community-based maternal health packages showed that this
community-based approach had a positive impact on the initiation of
breastfeeding within one hour of birth.[69] Some
programs have had adverse effects. One example is the “Formula for Oil” relief
program in Iraq, which resulted in the replacement of breastfeeding for
formula, which has negatively affected infant nutrition.[1]
In
April 2010, the World Bank and the IMF released a policy briefing entitled
“Scaling up Nutrition (SUN): A Framework for action” that represented a
partnered effort to address the Lancet’s Series on under nutrition, and the
goals it set out for improving under nutrition.[70] They
emphasized the 1000 days after birth as the prime window for effective
nutrition intervention, encouraging programming that was cost-effective and
showed significant cognitive improvement in populations, as well as enhanced
productivity and economic growth.[70] This
document was labeled the SUN framework, and was launched by the UN
General Assembly in
2010 as a road map encouraging the coherence of stakeholders like governments, academia, UN system
organizations and foundations in working towards reducing under nutrition.[70] The
SUN framework has initiated a transformation in global nutrition- calling for
country-based nutrition programs, increasing evidence based and cost–effective
interventions, and “integrating nutrition within national strategies for gender equality,
agriculture, food security,social protection,
education, water supply, sanitation, and health care”.[70]Government
often plays a role in implementing nutrition programs through policy. For
instance, several East Asian nations have enacted legislation to increase
iodization of salt to increase household consumption.[1] Political
commitment in the form of evidence-based effective national policies and
programs, trained skilled community nutrition workers, and effective
communication and advocacy can all work to decrease malnutrition.[41]Market
and industrial production can play a role as well. For example, in thePhilippines,
improved production and market availability of iodized salt increased household
consumption.[1] While
most nutrition interventions are delivered directly through governments and
health services, other sectors, such as agriculture, water and sanitation, and
education, are vital for nutrition promotion as well.[2]
Nutrition
is taught in
schools in many countries. In England and Wales thePersonal and Social Education and
Food Technology curricula include nutrition, stressing the importance of a
balanced diet and teaching how to read nutrition labels on packaging. In many
schools a Nutrition class will fall within the Family and Consumer Science or
Health departments. In some American schools, students are required to take a
certain number of FCS or Health related classes. Nutrition is offered at many
schools, and if it is not a class of its own, nutrition is included in other
FCS or Health classes such as: Life Skills, Independent Living, Single
Survival, Freshmen Connection, Health etc. In many Nutrition classes, students
learn about the food groups, the food pyramid, Daily Recommended Allowances,
calories, vitamins, minerals, malnutrition, physical activity, healthy food
choices and how to live a healthy life.
A
1985 US National Research Council report
entitled Nutrition
Education in US Medical Schools concluded
that nutrition education in medical schools was inadequate.[71] Only
20% of the schools surveyed taught nutrition as a separate, required course. A
2006 survey found that this number had risen to 30%.[72]
Humans
have evolved as omnivorous hunter-gatherers over
the past 250,000 years. The diet of early modern humans varied significantly
depending on location and climate. The diet in the tropics tended to be based
more heavily on plant foods, while the diet at higher latitudes tended more
towards animal products. Analysis of postcranial and cranial remains of humans
and animals from the Neolithic, along with detailed bone modification studies
have shown that cannibalism was also prevalent among prehistoric humans.[73]
Agriculture developed
about 10,000 years ago in multiple locations throughout the world, providing
grains such as wheat, rice, maize, andpotatoes, with
staples such as bread, pasta, and tortillas. Farming
also provided milk and dairy products, and sharply increased the availability
of meats and the diversity of vegetables. The importance of food purity was
recognized when bulk storage led to infestation and contamination risks.Cooking developed
as an often ritualistic activity, due to efficiency and reliability concerns
requiring adherence to strict recipes and procedures, and in response to
demands for food purity and consistency.[74]
The
first recorded nutritional experiment is found in the Bible's Book of Daniel.
Daniel and his friends were captured by the king of Babylon during
an invasion of Israel. Selected as court servants, they were to share in the
king's fine foods and wine. But they objected, preferring vegetables (pulses) and water in
accordance with their Jewish dietary
restrictions. The king's chief steward reluctantly agreed to a trial. Daniel
and his friends received their diet for 10 days and were then compared to the
king's men. Appearing healthier, they were allowed to continue with their diet.[75]
Anaxagoras
Around
475 BC, Anaxagoras stated
that food is absorbed by the human body and therefore contained
"homeomerics" (generative components), suggesting the existence of
nutrients.[74] Around
400 BC, Hippocrates said,
"Let food be your medicine and medicine be your food."[76]
In
the 16th century, scientist and artist Leonardo da Vinci comparedmetabolism to
a burning candle. In 1747, Dr. James Lind, a
physician in the British navy, performed the firstscientific nutrition
experiment, discovering that lime juice
saved sailors who had been at sea for years from scurvy, a deadly and painful bleeding disorder.
The discovery was ignored for forty years, after which British sailors became
known as "limeys." The essential vitamin C within
lime juice would not be identified by scientists until the 1930s.
Around
1770, Antoine Lavoisier,
the "Father of Nutrition and Chemistry" discovered the details of
metabolism, demonstrating that the oxidation of
food is the source of body heat. In 1790, George Fordyce recognizedcalcium as
necessary for fowl survival. In the early 19th century, the elements carbon, nitrogen, hydrogen and oxygen were
recognized as the primary components of food, and methods to measure their
proportions were developed.
In
1816, François
Magendie discovered
that dogs fed only carbohydratesand fat lost
their body protein and
died in a few weeks, but dogs also fed protein survived, identifying protein as
an essential dietary component.[citation needed] In
1840, Justus Liebig discovered
the chemical makeup of carbohydrates (sugars), fats (fatty acids) and
proteins (amino acids). In the
1860s, Claude Bernard discovered
that body fat can be synthesized from carbohydrate and protein, showing that
the energy in blood glucose can
be stored as fat or as glycogen.
In
the early 1880s, Kanehiro Takaki observed
that Japanese sailors (whose diets consisted almost entirely of white rice)
developed beriberi (or
endemic neuritis, a disease causing heart problems and paralysis) but British
sailors and Japanese naval officers did not. Adding various types of vegetables
and meats to the diets of Japanese sailors prevented the disease.
In
1896, Baumann observed iodine in
thyroid glands. In 1897, Christiaan
Eijkman worked
with natives of Java, who also
suffered from beriberi. Eijkman observed that chickens fed the native diet of
white rice developed the symptoms of beriberi, but remained healthy when fed
unprocessed brown rice with the outer bran intact. Eijkman cured the natives by
feeding them brown rice, discovering that food can cure disease. Over two
decades later, nutritionists learned that the outer rice bran contains vitamin
B1,
also known as thiamine.
In
the early 20th century, Carl von Voit and Max Rubner independently
measured caloric energy
expenditure in different species of animals, applying principles of physics in
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