According to the WHO,
Nutrition is the intake of food, considered in relation to the body’s dietary
needs. Good nutrition – an adequate, well balanced diet combined with regular
physical activity – is a cornerstone of good health. Poor nutrition can lead to
reduced immunity, increased susceptibility to disease, impaired physical and
mental development, and reduced productivity.
In hospitals, nutrition
may refer to the food requirements of patients, including nutritional solutions
delivered via an IV (intravenous) or IG (intragastric) tube.
Nutritional science
studies how the body breaks food down (catabolism) and repairs and creates
cells and tissue (anabolism) - catabolism and anabolism metabolism. Nutritional
science also examines how the body responds to food.
Brigham
Young University states that "nutritional Science investigates the
metabolic and physiological responses of the body to food and diet, including
the role of nutrients in the cause, treatment, and prevention of disease."
Nutrition is present in
all processes of life. Right from the very moment the sperm fertilizes an egg,
through fetal development in the uterus, to the birth, human growth, maturity,
old age, and eventual death. Even after death the human body serves as
nutrition for other organisms. Anything that involves life and chemical or
biochemical movement has nutrition at its core.
Anything that lives is
dependent on energy, which results from the combustion of food.
Types of Nutrients
As of 2014, nutrients
are thought to be of two types: macro-nutrients which are needed in
relatively large amounts, and micronutrients which are needed in smaller
quantities. The macronutrients include Carbohydrates, fibers and Micronuritents
such as Antioxidants and phytochemicals which are said to influence and protect
our body system. Most foods contain a mix of some or all of the nutrient types,
together with other substances, such as toxins of various sorts. 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 excessive amounts.
This macronutrients which
includes Carbohydrate(provides energy), the Protein(amino acids that provide
structural material), Dietary Fiber (reduces constipation and gastrointestinal
problems), Lipids(cell membranes and some other molecules are built). The
Energy been provided is measured either in kilocalories (kcal) or Joules. 1
kcal = 4185.8 joules.
Carbohydrate
Carbohydrates are
polyhydroxyl alcohols having potentially active aldehydes and ketones. They are
made up of Carbon, Hydrogen and Oxygen atoms bonded together. They include
Monosaccharide; disaccharides can be referred to Simple Carbohydrate.
Oligosaccharides and Polysaccharides which can be referred to as complex
carbohydrate. They constitute a large part of Rice, Yam, Noodles and bread.
Some simple carbohydrates
follow metabolic that result in the catabolism to glucose, while
Nutritionally, polysaccharides are more favored for humans because they are
more complex molecular sugar chains and take longer to break down - the more
complex a sugar molecule is the longer it takes to break down and absorb into
the bloodstream, and the less it spikes blood sugar levels. Spikes in blood
sugar levels are linked to heart and vascular diseases.
Protein
Proteins are complex
biological substances necessary to build protoplasm. They are largely peptides
and consist of units called amino acids. All proteins contains carbon hydrogen,
oxygen, and nitrogen. Some contain Sulphur, phosphorus, iron iodine and other
elements. They are usually from plants or animal origin. Every function in the
living cell depends on proteins. Excess amino acids are discarded, typically in
the urine. For all animals, some amino acids are essential (an animal cannot
produce them internally) and some are non-essential (the animal can produce
them from other nitrogen-containing compounds). Excess amino acids from protein
can be converted into glucose and used for fuel through a process called
Gluconeogenesis.
Fiber
Dietary fiber is the part
of a plant that is resistant to the body’s digestive enzymes. Only a relatively
small amount of fiber is digested or metabolized in the stomach or intestines.
Most of it ends up in the stool. Although most fiber is not digested, it
delievers several important health benefits, it retains water resulting in
softer and bulkier stool that prevents constipation and hemorrhoids. A high
fiber diet also reduces the risk of colon cancer, perhaps by speeding the rate
which stool passes through the intestine and by keeping the digestive system
clean, in addiction fiber finds substances that would normally result in the
production of cholesterol, and eliminates these substances from the body, it
helps lower Blood cholesterol levels, reducing the risk of heart disease. It
may help lower blood glucose levels because it can slow the absorption of
sugar. Additionally, fiber, perhaps especially that from whole grains, is
thought to possibly help lessen insulin spikes, and therefore reduce the risk
of type 2 diabetes.
Fats
Molecules consist of
carbon, hydrogen, and oxygen atoms. Fats are triglycerides - three molecules of
fatty acid combined with a molecule of the alcohol glycerol. Fatty acids are
simple compounds (monomers) while triglycerides are complex molecules (polymers).
Humans have a requirement for certain essential fatty acids such as Linoleic
acid(omega 6 fatty acids) and alpha-linolenic acid (omega 3 fatty acids) in the
diet because they cannot be synthesized from simple fatty acid in the diet.
Omega 6 can be found in vegetable oils while omega 3 is found in the green
leaves of plants and in selected seeds, nuts and legumes and also found in fish
oils.
Water
About 70% of the non-fat
mass of the human body is water. Nobody is completely sure how much water the human
body needs - claims vary from between one to seven liters per day to avoid
dehydration. We do know that water requirements are very closely linked to body
size, age, environmental temperatures, physical activity, different states of
health, and dietary habits.
Somebody who consumes a
lot of salt will require more water than another person of the same height, age
and weight, exposed to the same levels of outside temperatures, and similar
levels of physical exertion who consumes less salt. Most blanket claims that
'the more water you drink the healthier your are' are not backed with
scientific evidence. The variables that influence water requirements are so
vast that accurate advice on water intake would only be valid after evaluating
each person individually.
Micronutrient
Dietary minerals are the
other chemical elements our bodies need, apart from carbon, hydrogen, oxygen
and nitrogen. The term "minerals" is misleading, and would be more
relevant if called "ions" or "dietary ions" (it is a pity
they are not called so). People whose intake of foods is varied and well
thought out - those with a well balanced diet - will in most cases obtain all
their minerals from what they eat.
Minerals are often artificially added to some foods to make up for
potential dietary shortages and subsequent health problems. The best example of
this is iodized salt - iodine is added to prevent iodine deficiency, which even
today affects about two billion people and causes mental retardation and
thyroid gland problems. Iodine deficiency remains a serious public health
problem in over half the planet.
Potassium: it is a systemic (affects entire body) electrolyte,
essential in co-regulating ATP.
Deficiency - Hypokalemia
(can profoundly affect the nervous system and heart).
Excess - Hyperkalemia
(can also profoundly affect the nervous system and heart).
Chloride - It is key for hydrochloric acid production in the stomach.
Deficiency -
hypochleremia (low salt levels, which if severe can be very dangerous for
health).
Excess - hyperchloremia
(usually no symptoms, linked to excessive fluid loss).
Calcium- It is important for muscle, heart and digestive health. Builds bone, assists in the synthesis and function of blood cells.
Phosphorus- It is a component of bones and energy processing.
Magnesium- It processes ATP and required for good bones.
Zinc- It is required by several enzymes.
Iron- It is required for proteins and enzymes, especially hemoglobin.
Deficiency - anemia.
Excess - iron overload
disorder; iron deposits can form in organs, particularly the heart.
Manganese - It is a cofactor in enzyme functions.
Deficiency - wobbliness,
fainting, hearing loss, weak tendons and ligaments. Less commonly, can be cause
of diabetes.
Excess - interferes with
the absorption of dietary iron.
Copper - it is a component of many redox (reduction and oxidation) enzymes.
Deficiency - anemia or
Pancytopenia (reduction in the number of red and white blood cells, as well as
platelets) and a Neurodegeneration.
Excess - can interfere
with body's formation of blood cellular components; in severe cases
convulsions, palsy, and insensibility and eventually death.
Iodine- it is required for the biosynthesis of thyroxine (a form of thyroid hormone).
Deficiency -
developmental delays, among other problems.
Excess - can affect
functioning of thyroid gland.
Selenium- it is a cofactor essential to activity of antioxidant enzymes.
Deficiency - Keshan
disease (myocardial necrosis leading to weakening of the heart), Kashing-Beck
disease (atrophy degeneration and necrosis of cartilage tissue).
Excess - garlic-smelling
breath, gastrointestinal disorders, hair loss, sloughing of nails, fatigue,
irritability, and neurological damage.
Molybdenum - It has a vital role in uric acid formation and iron utilization, in carbohydrate metabolism, and sulfite detoxification.
Vitamins
Vitamins are
recognized as organic essential nutrients, necessary in the diet for good
health. (Vitamin D is the exception: it can be synthesized in the skin, in the
presence of UVB 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. Vitamins
are classified as water soluble (they can dissolve in water) or fat soluble
(they can dissolve in fat). For humans there are 4 fat-soluble (A, D, E, and K)
and 9 water-soluble (8 B vitamins and vitamin C) vitamins, a total of 13.
Water soluble vitamins
need to be consumed more regularly because they are eliminated faster and are
not readily stored. Urinary output is a good predictor of water soluble vitamin
consumption. Several water-soluble vitamins are manufactured by bacteria.
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