Transcript 03 Scientific basis of nutrition

Hygiene of nutrition, its ecological
and social problems.
Hygienic examination of quality of
food products. Scientific bases of
rational, preventive, dietary and
treatment food.
Аuthor:
Lototska O.V
1
Nutrition may be defined as
the science
of food and its
relationship to health. It is
concerned primarily with the part
played by nutrients in body
growth,
development
and
maintenance.
The word nutrient or "food factor" is used for
specific dietary constituents such as proteins,
vitamins and minerals. Dietetics is the practical
application of the principles of nutrition; it includes
the planning of meals for the well and the sick. Good
nutrition means "maintaining a nutritional status that
enables us to grow well and enjoy good health".
In various historical times structure of
nutrition and character of a nutrition
changed depending on
 development of industrial forces of a
society,
 climate-geographical conditions,
 direction of economic activity and so
on.
The character of nutrition of the
population was formed gradually
depending on an economic and cultural
level of development of the country, in
view of national customs and features.
Through centuries, food has been
recognized as important for human
beings in health and disease.
Good nutrition is a basic component of health.
The relation of nutrition to health may be seen from
the following view points:
Growth
and
development:
Good
nutrition is essential for
the attainment of normal
growth and development.
Not only physical growth
and development, but
also
the
intellectual
development,
learning
and
behaviour
are
affected by malnutrition.
Specific deficiency: Malnutrition is directly responsible
for certain specific nutritional deficiency diseases.
Good nutrition therefore
is essential for the
prevention of specific nutritional deficiency diseases
and promotion of health.
Resistance to infection: Infection, in turn, may aggravate
malnutrition by affecting the food intake, absorption
and metabolism.
Mortality and morbidity: The
indirect
effects
of
malnutrition
on
the
community are even more
striking - a high general
death
rate,
high
infant
mortality rate, high sickness
rate and a lower Expectation
of life.
'You are what you eat',
some people say.
If you eat rubbishy food,
you can't really expect to
grow up strong and
healthy.
But if you eat goodquality food, you've a
good chance of doing so.
That's just commonsense
really.
Generally, a healthy diet is said to include:
•Sufficient calories to maintain a person's metabolic
and activity needs. For most people the
recommended daily allowance of energy is 2,000
calories, but it depends on age, sex, height, weight,
and physical activity.
•Sufficient quantities of fat, including monounsaturated
fat, polyunsaturated fat and saturated fat, with a
balance of omega-6 and long-chain omega-3 lipids.
The recommended daily allowance of fat is 65-80
grams.
•Maintenance of a good ratio between carbohydrates
and lipids (4:1): four grams of the first for one gram of
the second.
•Avoidance of excessive saturated fat
•Avoidance of trans fat.
•Essential micronutrients such as
vitamins and certain minerals.
•Sufficient essential amino acids ("complete protein") to
provide cellular replenishment and transport proteins.
All essential amino acids are present in animals. A
select few plants (such as soy and hemp) give all the
essential acids. A combination of other plants may also
provide all essential amino acids (except rice and
beans which have limitations).
•Avoiding directly poisonous (e.g. heavy metals) and
carcinogenic (e.g. benzene) substances;
•Avoiding foods contaminated by human pathogens
(e.g. E. coli, tapeworm eggs);
•Avoiding chronic high doses of certain
foods that are benign or beneficial in small
or occasional doses, such as
foods that may burden or exhaust normal
functions (e.g. refined carbohydrates without
adequate dietary fiber);
foods that may interfere at high doses with
other body processes (e.g. refined table
salt);
foods or substances with directly toxic
properties at high chronic doses (e.g. ethyl
alcohol).
•Combination of foods eaten and timing of meals so
that hunger is kept in check.
Food Guide Pyramid
Function of nutrition
Provision of energy
Body building and repair
Maintenance and regulation of
tissue functions
CLASSIFICATION OF FOODS
1.Classification by predominant functions:
Energy-giving foods. These constitute fats and
carbohydrates. They are also called protein sparer. Proteins
also produce energy to some extent. Cereals, roots and tubers,
dried fruits, sugars and fats belong to this group. They supply
heat and energy to the body.
Body building foods. These are foods rich in proteins,
mineral salts and water. Milk, meat, fish, pulses, oilseeds and
nuts fall in this category.
Protective foods. These constitute inorganic salts, vitamins
and minerals. They include proteins and water. Milk, eggs,
liver, green leafy vegetables and fruits are included in this
group. They build our bones, teeth, muscles, soft tissues, blood
and other body fluids. They provide material for repair in the
body as wear and tear goes on constant.
2. Classification by origin:
• Foods of animal origin
• Foods of vegetable origin
3. Classification by chemical
composition:
• Proteins
4. Classification by nutritive value:
• Fats
•Cereals and millets
• Carbohydrates
•Pulses (legumes)
• Vitamins
•Vegetables
• Minerals
•Nuts and oilseeds
•Fruits
•Animal foods
•Fats and oils
•Sugar and jaggery
•Condiments and spices
•Miscellaneous foods
Balanced diet is one, which will meet a person's
caloric need and contain all nutrients, particularly
proteins, and vitamins. In addition, the food should
satisfy the taste and desire of a person and should
have enough roughage to promote the peristalsis.
Balanced diet should have 50-60 % carbohydrates
30-35 % fats and 10-15 % proteins with necessary
vitamins and minerals. A balanced diet must
contain foods from the above three groups.
Importance of the main components
of food in nutrition of the man
Nutrients are organic and inorganic
complexes contained in food. There are about
50 different nutrients which are normally
supplied through the foods we eat. Each
nutrient has specific functions in the body.
Most natural foods contain more than one
nutrient. These may be divided into :
(i) Macronutrients: These are proteins, fats and
carbohydrates which are
often
called
"proximate principles" because they form the
main bulk of food.
(ii) Micronutrients : These are vitamins and
minerals. They are called micronutrients
because they are required in small amounts
which may vary from a fraction of a milligram
to several grams.
PROTEINS
The word "protein" means that which is of first importance.
Indeed they are of the greatest importance in human nutrition.
Proteins are composed of carbon, hydrogen, oxygen, nitrogen
and sulphur in varying amounts. Some proteins also contain
phosphorus and iron and occasionally other elements. Proteins
differ from carbohydrate and fat in the respect that they
contain nitrogen. Proteins are made up of simpler substances,
called amino acids. These are the building blocks of protein
Some 22 amino acids are stated to be needed by the human
body, out of which eight are called "essential".
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•
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Proteins are needed by the body:
For growth and development: They furnish the building
material, i.e. the amino acids from which the body proteins
are synthesized.
For repair of body tissues and their maintenance: It has
been shown that the body proteins are constantly being
broken down; they have to be replaced for which fresh
protein intake is required.
For synthesis of antibodies, enzymes and hormones:
Antibodies, enzymes and hormones contain protein. The body
requires protein to produce them.
Proteins can also furnish energy to the body, but generally
the body depends for its energy on carbohydrates and fats
rather than proteins.
Sources of protein
Animal sources:
Plant sources:
Protein requirements
Doctors recommended 1,0 g. protein/kg body
weight for an adult.
Daily allowances recommended by experts of
the World Health Organization (Geneva, 1976)
is 37 g of protein per day for the standard man
with mass of body 65 kg for professions of
average hardness (II group) and 29 g of protein
for the standard woman with body mass 55 kg.
Effects of protein deficiency:
Adults:
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Loss of weight,
underweight,
poor musculature,
anemia,
increased susceptibility to infection,
frequent loose stools,
general lethargy,
incapacity to sustained work,
delay in wound healing,
cirrhosis of liver,
oedema,
ascitis, etc.
Fats are composed chemically of carbon, hydrogen
and oxygen, only in different proportion than they are
contained in carbohydrates. There is less of oxygen in
fats than in carbohydrates. Fats are a form of
concentrated food and like carbohydrates, they are
used as body fuels for the production of heat and
energy. As fats are not soluble in water, the process
of digestion changes the fat into an emulsion form for
their absorption into the body. Liquid fats and those
which melt at body temperature are somewhat better
digested than those which are much harder.
Fats serve the following functions:
• Dietary fat is a concentrated source of energy.
One gram of fat supplies 9 calories of energy.
• Fats are carriers of fat-soluble vitamins, e.g., vitamins
A, D, E and K.
• Dietary fat supplies "essential fatty acids".
Linoleic acid, one of the essential fatty acids, prevents
scaly skin formation.
• The fat layer below the skin plays an important role in
maintaining our body temperature.
• Fats provide support for many organs in the body
such as heart, kidney, intestine etc.
• Foods containing fats are tasty.
Animal sources:
These are ghee, butter, fat of
meat, fish oils, etc.
Vegetable sources: These are various
vegetable oils such as groundnut,
gingely, mustard, cottonseed,
safflower (kardi) and coconut oil.
CARBOHYDRATES
Chemically
carbohydrates
are
composed of carbon, hydrogen and
oxygen
as
the
name
implies.
Polysaccharides are various starches
which are converted into two
molecules saccharides i.e. cane sugar,
beet sugar, milk sugar and malt sugar.
These on further, glucose and
digestion change into single molecule
monosaccharides fructose.
Foods that are high in
carbohydrates: Breads,
pastas, beans, potatoes, bran,
rice and cereals.
The original source of all starches and sugars is green
plants. When plants have excessive sugar and they need
to store it, as reserve supply of food, plant body is
capable of changing its sugar into starch. Carbohydrates
are abundantly present in food. All carbohydrates have
to be changed into glucose and fructose before they can
be absorbed into the body.
1 gm of carbohydrates yields 4.1 calories of heat.
The daily requirement of carbohydrates varies from
50 to 60% of total energy intake.
The carbohydrates are chief sources of energy. In the
active muscles, the glucose is oxidized for the
production of energy and warmth. Glucose which cannot
be used immediately, is converted into glycogen and
stored in the liver and muscles or converted into fat and
stored under the skin.
There are three main sources of carbohydrate:
Starches:
These are present in cereals
(rice, wheat); roots and
tubers (potatoes).
Sugars:
(a) Monosaccharides: glucose, fructose,
galactose.
(b) Disaccharides: Sucrose, lactose, maltose.
(c) Cellulose: This is the tough fibrous lining
found in vegetables, fruits, cereal, etc.
It is hard to digest and has no nutritive value.
However, cellulose acts as "roughage" and
prevents constipation.
VITAMINS
These are complex organic substances contained
in food and are very essential for the normal
growth and nutrition of animals. In fact, they are
vital accessory food factors required for the
maintenance of optimum, health. They are present
in various foods in minute quantities and diet
devoid of vitamins, if taken for some period, gives
rise to certain diseases known as deficiency
diseases and may ultimately even cause death.
They do not supply energy but are simply
protective foods.
vitamins
Water-soluble
Vitamins
Fat -soluble
Vitamins
Thiamine (B1)
A (retinol)
Riboflavin (B2)
Niacin (B3)
Pyridoxine (B6)
Pantothenic acid
Cobalamin (B12)
Ascorbic acid
Folic acid
E (tocopherol)
D (calciferol)
K (menadione)
Diseases, that is direct or mediate
related with a nutrition
1. Alimentary disease,
illness caused by
deficiency or
surplus of
components of
nutrition.
The
secondary
illnesses of insufficiency
or excessive nutrition,
which is developed as
complication
on
a
background
of
wearisome
illnesses
(surgical,
infectious,
oncology and others.)
2.
3. Disease of
multifactor nature
that very much
frequently
develops on a
background of
genetic
predilection, for
example,
atherosclerosis,
gout, idiopathic
hypertension, etc.
4. Disease, which
are transferred by a
nutritional way
(some infections
diseases and
intestinal worms,
alimentary
poisonings).
5. Alimentary
intolerance atypical reaction to
nutrition, for
example alimentary
allergy,
idiosyncrasy.
Illnesses caused by improper nutrient
consumption
NUTRIENTS
DEFICIENCY
EXCESS
Calories
Starvation
Obesity, diabetes
mellitus, Cardiovascular
disease
Simple
carbohydrates
Marasmus,
starvation
diabetes mellitus
Complex
carbohydrates
Marasmus,
starvation
Obesity
Saturated fat /
trans fat
none
Cardiovascular disease,
Unsaturated fat
Rabbit
starvation
Obesity
Cholesterol
none
Cardiovascular
disease
Protein
Marasmus
Sodium
hyponatremia
Iron
Anemia
Ketoacidosis,
Rabbit starvation,
kidney disease
Hypernatremia,
hypertension
Hepatitis C,
cirrhosis, heart
disease
Iodine
Goiter,
hypothyroidism
Iodine Toxicity
(goiter,
hypothyroidism)
Vitamin A
Xerophthalmia and
Night Blindness
Vitamin B1
Beri-Beri
Vitamin B2
Cracking of skin and
Corneal Unclearation
Niacin
Pellagra
Vitamin B12
Pernicious Anemia
Vitamin C
Scurvy
diarrhea causing
dehydration
Vitamin D
Rickets
Hypervitaminosis D
(dehydration, vomiting,
constipation)
Vitamin E
Hypervitaminosis A
(cirrhosis, hair loss, birth
defects)
dyspepsia, cardiac
arrhythmias, birth defects
Hypervitaminosis E
(anticoagulant: excessive
bleeding)
Nutritional Diseases:
1. Protein Calorie Malnutrition
(PCM).
(i)
Kwashiorkor. It results from
consumption of very low protein in
diets of low biological values, yet
providing just enough energy to
satisfy the needs of the child. This
condition is usually seen in children
between the age group of 1-4 years.
This symptom is characterized by
pitting
oedema,
anemia,
retarded growth, loss of
appetite, diarrhoea, scanty
hair growth...
• (ii) Marasmus. It is a clinical condition
of
protein
energy
malnutrition,
primarily due to total deprivation of
the requisite calories required by the
body. It usually occurs in the age
group of 1/2 to 5 years. This
syndrome is characterized by failure
to gain weight, wasting of
muscles and of subcutaneous fat.
The child feels good appetite but
is irritable.
• (iii) Marasmic-Kwashiorkor. Patients
suffering from Marasmic-Kwashiorkor
show clinical symptoms of both
Marasmus and Kwashiorkor.
3. Mineral Deficiencies
(i) Deficiency of iodine in water and feed leads to
goitre or cretinism.
3. Mineral Deficiencies
(ii) Lack of flourine ( < 0.5
ppm) in water leads to
caries.
(iii) Calcium deficient diets
lead to rickets and
osteomalacia.
3. Mineral Deficiencies
(iv) Iron deficiency diets lead to anaemia,
(v) There are other important minerals like copper,
selenium etc. Usually their requirements are so
little that deficiency conditions do not occur.
4. Vitamins Deficiencies
(i)Lack of vitamin A results in xerophthalmia,
Bitot's
spots,
night
blindness
and
keratomalacia.
4. Vitamins Deficiencies
(ii) B Complex:
Deficiency of Thiamine
leads to beriberi.
Niacin deficiency results in
pellagra.
Riboflavin deficiency
symptoms
are
angular
stomatitis,
cheilosis,
scrotal
dermatitis
and
corneal
vascularisation.
(iii) Vitamin C deficiency leads to scurvy, spongy bleeding
gums, haemorrhages in skin and other haemorrhages,
(iv) Vitamin
osteomalacia.
D
deficiency
result
in
rickets
and
(v) Vitamin K deficiency leads to hypoprothrombinaemia,
which further leads to haemorrhages.
5. Problems of Overnutrition (eating too much)
Proteins/fats/carbohydrates
•
Cardiovascular disease
•
Some cancers
•
Diabetes mellitus
•
Insulin resistance
•
•
Obesity The main features of obesity are
overweight and fatness. It is mostly caused by
overeating and intake of abundance of calories
Metabolic syndrome
Vitamin poisoning
•
(i) Hypervitaminosis A is at times caused by excess
of vitamin A therapy. The manifestation are
headache, nausea, vomiting, irritability and anorexia.
Carotenaemia is also caused due to excessive
consumption of carrots which is characterised by
yellow skin with normal conjunctiva
Vitamin poisoning
(ii) The toxic manifestations of hypervitaminosis D are
anorexia, nausea, vomiting, thirst, polyuria and
drowsiness. Calcium and phosphorus levels in
serum and urine are raised. Calcium may be
deposited in many tissues also
(iii)
Fluorosis
occurs
if
fluorine is available > 1,5
mg in 1 liter water. It is
characterised by (a) dental
fluorosis,
i.e.,
mottled
enamel of teeth and
(b) skeletal fluorosis
i.e.,
dense
bone
formation,
severe
spondylitis and even
calcifications
of
ligaments of spine and
tendinous inflamation
of other muscles in
severe cases.
Food allergies
Some people have allergies or sensitivities to
foods which are not problematic to most people.
This occurs when a person's immune system
mistakes a certain food protein for a harmful foreign
agent and attacks it. About 2% of adults and 8% of
children have a food allergy.
Commonly food allergens are gluten, corn, shellfish
(mollusks), peanuts, and soy. Most patients present with
diarrhea after ingesting certain foodstuffs, skin
symptoms (rashes), bloating, vomiting and regurgitation.
The digestive complaints usually develop within half an
hour of ingesting the allergen.
Rarely, the food allergy chelce can lead to
anaphylactic shock: hypotension (low blood pressure)
and loss of consciousness. This is a medical emergency.
An allergen associated with this type of reaction is
peanut, although latex products can induce similar
reactions.
Depending on quality the food-stuff can
be divided on such groups:
1.Products of high quality - the products which may be
used without restrictions.
2. Non-standard. The products, which have the
certain deviations from requirements of state
standards or specifications, but it does not interfere to
their realization (for example, chicken eggs of mass
less 40g etc.).
3. Conditionally suitable. It is products, which can be
used after additional processing.
4. Substitutes (ersatz). The products with reduced
value as natural substitutes, for example, barley and
acorn coffee. They are allowed to realization, provided
that the consumer would be informed, what kind
product is offered to him.
5. Food Adulteration
It is products, in which
premeditatedly qualitative structure are changed to
hide the certain disadvantages or sings of decay. Such
products are forbidden to realize to the population.
6. Low-quality. The products concern to those, which
are not suitable to nutrition in any way, that is, which
have the expressed signs of decay (rotting, etc.).
Food poisoning
is an acute illness
caused
by
ingestion of food
contaminated by
bacteria, bacterial
toxins,
viruses,
natural poisons, or
harmful chemical
substances.
There are 3 types of food
poisoning :
bacterial (microbic)
etiology
non -bacterial (nonmicrobic) etiology
There are three main types of causes of
food poisoning:
Biological hazards:
•
•
•
•
viruses
bacteria
toxins
parasites
•
•
•
•
pesticides
preservatives
cleaning supplies
toxic metals
Chemical hazards:
Physical hazards:
• foreign objects (e.g., hair, glass, staples) that
contaminate food accidentally
• naturally occurring objects (e.g., bones, leaves or
stems)
Food usually becomes contaminated from poor
sanitation or preparation. Food handlers who do not
wash their hands after using the bathroom or have
infections themselves often cause contamination.
Improperly packaged food stored at the wrong
temperature also promotes contamination.
The typical symptoms of food poisoning are:
•Diarrhea
•Vomiting
•Stomach Cramps
•Headache
•Fever
Food poisoning by bacterial
etiology
Food poisoning by bacterial etiology are
divided into:
 Food infections (toxic-infections),
• Food toxemia ( Food toxicosis),
•mixes (mixed etiology).
Food infections (Toxic-infections)
- are diseases caused by microorganisms, which in a
great many got into organism and poisoned it by the
toxins.
The cause of toxic-infection can be
E.coli bacteria,
genus Proteus,
Cl.Perfringens,
Bac.Cereus,
Vibrio parahaemolyticus,
Enterococcus and other unstated microorganisms.
.
Food toxemia
Food toxemia (Food-toxicosis) - diseases
caused y toxins, produced in food products by
toxic strains of Clostridium botulinum and
Staphylococcus aureus.
• Botulism is a disease caused by the toxins (poisons)
produced by several members of the group of
bacteria called Clostridium botulinum. These
bacteria are found in soil throughout the world and
produce spores that are able to survive in a dormant
state until more favourable conditions allow them to
grow.
Botulism in humans is most often
the result of eating food containing
the toxin. Botulinum neurotoxins
are also a serious bioterrorism
concern because the toxins are
relatively easy to make and deliver
and are highly lethal.
Symptoms produced by each toxin type are quite
similar. The first symptoms of botulism may include
• Double vision
• Blurred vision
• Drooping eyelids
• Slurred speech
• Difficulty swallowing
• Dry mouth
• Muscle weakness
Symptoms of foodborne botulism usually
begin within 18 to 36 hours after eating
contaminated food, but can occur in as
few as 6 hours or as much as 10 days
afterward.
Staphylococcus aureus
This bacteria is frequently present in human skin, hair,
nasal cavity, throat and wounds.
Foods (e.g. lunch boxes,
cakes,
pastries,
sandwiches)
which have been subject to
various handling procedures, with
no
subsequent
cooking
or
reheating before consumption, are
easily
contaminated
by
Staphylococcus aureus. Symptoms
of food poisoning caused by
Staphylococcus aureus include
nausea, vomiting, abdominal pain,
diarrhea etc.
Poisoning classification of nonmicrobic origin
Poisoning
by
products,
poisonous by its nature
Poisoning by products, which
become toxic for some time
Poisoning by admixtures of
chemically toxic substances
Poisoning by products, poisonous by
its nature :
1.Vegetable origin:
- poisoning by mushrooms (amanita phalloides, amanita
virosa, entoloma lividum, hypholoma fasciculare);
- poisoning by plants (datura stramonium, hyoscyamus
niger, conium maculatum, atropa belladonna, aconitum,
sambucus nigra, ect.);
2.Animal origin: -
roes of some types of fishes
Mushroom Poisoning
All poisonous mushrooms cause vomiting and
abdominal pain. Other symptoms vary greatly
depending on mushroom type. Generally, mushrooms
that cause symptoms early (within 2 hours) of
ingestion are less dangerous than those that cause
symptoms later (usually after 6 hours).
Amanita muscaria
AMANITA FALLOIDES
Poisonous fish
Datura stramonium
Atropa
Belladonna
Poisoning by products,which become toxic
for some time.
1.Vegetable origin:
•kernels of stone-fruits drupe (apricots, peaches,
cherries);
•-
bean of uncooked (raw) haricot;
•-
germinated and green potatoes.
2.Animal origin:
•liver of some types of fishes (pike, mackerel
(scomber);
•- honey in some time .
Poisoning by admixtures of
chemically toxic substances
•
pesticides;
•
heavy metals;
• nitrates and nitrites.
Prevention
Safe steps in food handling, cooking,
and storage are essential to avoiding
food-borne illness. Bacteria cannot be
seen, smelled, or tasted, which may
be on any food.
Safe shopping
•Buy cold foods last during your
shopping trip. Get them home fast.
•Never choose torn or leaking
packages.
•Do not buy foods past their "sell-by"
or expiration dates.
•Keep raw meat and poultry separate
from other foods.
Safe storage of foods
•Keep it safe; refrigerate.
•Unload perishable foods first and
immediately refrigerate them. Place raw
meat, poultry, or fish in the coldest section
of your refrigerator.
•Check the temperature of your
appliances. To slow bacterial growth, the
refrigerator should be at 40°F, the freezer
at 0°F.
•Cook or freeze fresh poultry, fish, ground
meats, and variety meats within two days.
Safe food preparation
•Keep everything clean!
•Wash hands before and after handling raw
meat and poultry.
•Sanitize cutting boards often in a solution of one teaspoon
chlorine bleach in one quart of water.
•Do not cross-contaminate. Keep raw meat,
poultry, fish, and their juices away from
other food. After cutting raw meats, wash
hands, cutting board, knife, and counter tops
with hot, soapy water.
•Marinate meat and poultry in a covered
dish in the refrigerator. Discard any
uncooked/unused marinade.
Safe cooking
•Cook ground meats to 160°F; ground
poultry to 165°F. Beef, veal, and lamb
steaks, roasts and chops may be
cooked to 145°F; all cuts of fresh
pork, 160°F. Whole poultry should
reach 180°F in the thigh; breasts
170°F.
•Keep hot foods hot and cold foods
cold.
•Never leave food out more than two
hours (or more than one hour in
temperatures above 90°F).
•Bacteria that cause food poisoning
grow rapidly at room temperature.
Thank you
for your attention!