Transcript File - Faculty Of Medicine

Faculty of Medicine
Introduction to Community Medicine Course
(31505201)
Unit 2 Nutrition and Nutrition Assessment and Diet
The Nutrients & their Categories.
By
Hatim Jaber
MD MPH JBCM PhD
27-09-2016
Attention!!!!!!!!
•
•
•
•
Week 2 Unit 2 Nutrition and Nutrition Assessment and Diet
Sun 25-9 Introduction and Terminology used in nutrition
Tue 27-9 The Nutrients & their Categories
Thu 29 -9 Spectrum of public nutrition problems: Malnutrition
& its Ecology and Common nutritional disorders in Jordan
• Week 3 Unit 2 (cont.) Nutrition and Nutrition Assessment and
Diet
• Sun 2-10 =====================================
• Tue 4-10 Assessment of Nutritional Status. Anthropometric
Assessment.
• Thu 6-10 Breast feeding & Breast milk. Formula feeding
Presentation outline
Time
Nutrients classifications
12:00 to 12:10
Macronutrients and their functions
12:10 to 12:30
Micronutrients and their functions
12:30 to 12:40
Water , vitamins and minerals
12:40 to 12:50
Background definitions
• Nutrients: “Chemical substances in food that nourish
the body by providing energy, building materials, and
factors to regulate needed chemical reactions.”
• (Organic and inorganic complexes contained in food
are called nutrients).
• Essential nutrients: Must be provided by food because
the body does not produce them in sufficient
quantities or can not make them at all.
• Nonessential nutrients: Healthy, well-nourished
bodies can make them in sufficient quantities to
satisfy their needs.
The Nutrients
Copyright 2005 Wadsworth Group, a division of Thomson Learning
Nutrients are classified into :
• A. Macronutrients (carbohydrates, fats,
and proteins).
1. Provide calories for energy
2. Needed in large quantities
• B. Micronutrients (vitamins, minerals,
and water).
Needed in smaller amounts
Six categories of nutrients
1. Carbohydrates: contain carbon, hydrogen, and
oxygen combined in small molecules called
sugars and large molecules represented
mainly by starch.
2. Lipids (fats and oils): contain carbon,
hydrogen, and oxygen as do carbohydrates,
but the amount of oxygen is much less.
Triglyceride is the main form of food fat.
3. Proteins: contain carbon, hydrogen, and
oxygen, plus nitrogen and sometimes sulfur
atoms arranged in small compounds called
amino acids. Chains of amino acids make up
dietary proteins.
Six categories of nutrients (cont’d):
4. Vitamins: are organic compounds that serve
to catalyze or support a number of
biochemical reactions in the body.
5. Minerals: are inorganic elements or
compounds that play important roles in
metabolic reactions and serve as structural
components in body tissues such as bone.
6. Water: is vital to the body as a solvent and
lubricant and as a medium for transporting
nutrients and waste.
about 45 essential nutrients
Energy and food
• The energy in foods is expressed as kilocalories.
One kilocalorie represents the amount of heat it
takes to raise the temperature of one liter of
water 1°C
• A person needs about 2000 kilocalories a day to
meet his or her energy needs. In common usage,
people refer to kilocalories as calories, which is a
much smaller energy unit:
1 kilocalorie contains 1000 calories.
Carbohydrates
• There are three types- sources of carbohydrates food sugar, starch and
cellulose
• 1- Sugar: Sugar is also called simple carbohydrate. Fruits, honey and sugar
are some sources of sugar.
• 2- Starch: starch is called complex sugar. Plants store energy in the form
of starch. When we eat plant products containing starch, our digestive
system breaks down starch into glucose. This glucose is absorbed in blood
and provides energy. Some foods give carbohydrates to our body in the
form of starch. These are cereals, potatoes, sweet potatoes etc. Some
other foods give carbohydrates in the form of sugar. For example sugar,
honey, jam, jiggery, etc.
Starch and sugar are the main source of energy and essential for
synthesis of certain non-essential amino acids
• 3- Cellulose: complex carbohydrates not digested but form the bulk of
stools.
---Optimum requirement of carbohydrate in balanced diet 50-70%of total
energy intake.
• One gram of carbohydrate gives four kcal.
• An adult person needs 400-420 gms of carbohydrates everyday.
Carbohydrates are classified into:
• Monosaccharide are seldom found free in
nature and are the simplest form of
carbohydrate.
• Disaccharides and polysaccharides consist of
monosaccharide linked together.
• Also carbohydrates are classified into simple
and complex carbohydrates.
• Monosaccharides: Glucose (blood sugar),
Fructose(fruit), Galactose (milk)
• Disaccharides: Sucrose (table sugar=glucose and
fructose), Lactose(milk- glucose and galactose),
Maltose
• Polysaccharides: (Starch in plants and Glycogen
in human and animals)
- Digestible: Amylose, Amylopectin, Resistant
starch, Dextrins and Glycogen (animal
carbohydrate)
- Indigestible: dietary fibers: cellulose, pectin,
gums….
Dietary Fiber and Functional Fiber
•
•
•
•
•
•
•
•
Cellulose
Beta-glucans
Chitin and chitosan
Hemicellulose
Pectins, gums, and mucilages
Fructans
Algal polysaccharides
Lignin
Role of Fiber in Digestion and
Absorption
•
•
•
•
•
•
•
Prevent constipation
Increase fecal volume
Decrease GI transit time
Slowed or decreased nutrient absorption
Bind cholesterol and minerals
Reduce the risk of cancer and GBS
Modify serum lipid concentrations
– Short-chain fatty acids
Glycemic Index (GI)
• Is the blood glucose response to a given food,
compared to standard food (glucose or white
bread)
• Relative ability of different dietary
carbohydrates to raise blood glucose levels
• Advantages of foods with low glycemic index
(GI)
Functions of Carbohydrates
Sources
-Give energy and feeling of
fullness
-increase the bulk of our food.
-Spare proteins to perform
other functions
-Helps to make the food tasty.
- Prevent ketosis
Starch sources: cereals – like
wheat rice, bajra, maize,
potatoes, sweet potatoes,
calocasia, etc.
sugar sources: sugar, honey,
jaggery, sweets, jam,
murabba, etc.
Proteins
Are nitrogenous compounds, composed of amino acids
Complete proteins:
• Foods containing all the essential amino acids
Examples: fish, meat, eggs, milk, cheese
Incomplete proteins:
• Foods that are missing some essential amino
acids Examples: Legumes, nuts, whole grains
Amino Acids and Protein
• Essential amino acids
• Nonessential amino acids
• 9 of the 20 amino acids are called
essential amino acids because you must
obtain them from the foods you eat
since your body cannot make them.
Structure and Function of the 20
Amino Acids Required by Humans
Amino acids marked with an asterisk (*) are essential.
Structure and Function of the 20 Amino Acids
Required by Humans–cont’d
Amino acids marked with an asterisk (*) are essential; those with a double asterisk (**) are essential in infants and in chronic diseases.
Structure and Function of the 20 Amino
Acids Required by Humans–cont’d
Amino acids marked with an asterisk (*) are essential; those with a double asterisk (**) are essential in infants and in chronic diseases.
Dietary Protein Quality
• Limiting amino acid
• Net protein utilization
• Protein digestibility corrected amino
acid score (PDCAAS)
• Denaturation
• Vegetable vs animal protein
• Food processing
• Complementary proteins
• High biological value protein(HBV protein):
any HBV protein in adequate amount
provides the body needs of amino acids ___
all animal proteins are HBV except gelatin
• Low biological value protein(lBV protein)
where some of essential amino acids are
either missing or of inadequate amount== all
plant except soybeans
Reference protein
• Ideal protein – is protein that fulfils the
following theoretical criteria:
- contains all essential amino acids in optimal
amount for human being
- fully digestible and utilizable by the body>
Functions
•
•
•
•
•
•
Formation cells: cytoplasm
Formation essential biological compounds : Hb
Regulation of fluids movement: osmotic pressure
Regulation the acid-base balance: as buffers
Supporting immune system: antibody
Production of energy: 4 kcal
Fats
• Fats are groups of insoluble compounds and
include:
- Fatty acids
- Triglycerides (glycerol: sugar alcohol+3 fatty acids)
95% of dietary fat = energy and storage
- Phospholipids: one phosphat +2 fatty acids
( brain, hormones and corticosteroids…)
- Cholesterols: LDL and HDL
•
•
•
•
•
cholesterol A waxy substance found in the blood and cells
and needed for synthesis of cell membranes, vitamin D, and
hormones.
low-density lipoprotein (LDL) Blood fat that transports
cholesterol to organs and tissues; excess amounts result in
the accumulation of fatty deposits on artery walls.
• high-density lipoprotein (HDL) Blood fat that helps
• transport cholesterol out of the arteries, thereby protecting
• against heart disease.
Types of Lipids
• Triglycerides
• Phospholipids (e.g., lecithin)
• Sphingolipids, alcohols, waxes,
isoprenoids, and steroids (including
cholesterol)
• Glycolipids
• Synthetic lipids (MCT, structured lipids,
fat replacers)
Other Lipid Issues:
Eicosanoid Synthesis
Fatty Acids
---essential acids to be supplied in food
•
•
•
•
Saturated (SFA)
Monounsaturated (MFA)
Polyunsaturated (PUFA)
Location of double bonds; how named:
– Omega-6
– Omega-3
• Essential fatty acids
Trans-Fatty Acids
Repeated heating UFA(plant)---TFA
• Trans versus cis format
• Sources of trans-fatty acids
– Partially hydrogenated margarine, shortening,
commercial frying fat, high-fat baked goods,
salty snacks
• Negative health effects: +LDL, -HDL,
neonatal…
Lipids
• Functions
– Energy (9 kcal/g)
– Organ positioning, protection
– Fat-soluble vitamins and phytochemicals
•
•
•
•
•
•
•
•
•
•
•
•
•
•
dietary fi ber Nondigestible carbohydrates and lignin that are
intact in plants.
functional fi ber Nondigestible carbohydrates either isolated
from natural sources or synthesized; these may be added to
foods and dietary supplements.
total fi ber The total amount of dietary fi ber and functional
fi ber in the diet.
soluble (viscous) fi ber Fiber that dissolves in water or is
broken down by bacteria in the large intestine.
insoluble fi ber Fiber that does not dissolve in water and is
not broken down by bacteria in the large intestine.
vitamins Carbon-containing substances needed in small
amounts to help promote and regulate chemical reactions and
processes in the body.
Vitamins
• Vitamins are organic (carbon-containing)
substances required in small amounts to
regulate various processes within living cells
• Humans need 13 vitamins; of these, four are
fat-soluble (A, D, E, and K), and nine are watersoluble (C and the B-complex vitamins thiamin,
r ibofl avin, niacin, vitamin B-6, folate, vitamin B12, biotin, and pantothenic acid).
Minerals—Inorganic Micronutrients
• Minerals are inorganic (non-carbon-containing)
elements you need in relatively small amounts
to help regulate body functions, aid in the
growth and maintenance of body tissues, and
help release energy
• Function: Assists with the
transport of materials in the body
by making up most of the liquid part
of blood (plasma), helps regulate
body temperature, and helps break
down food in the digestive system
• Food sources: vegetables, fruit,
milk
Water—Vital but Often Ignored
• Water is the major component in both foods
and the human body: You are composed of
about 50–60% water.
• You can live up to 50 days without food but
only a few days without water.
Other Substances in Food
• Antioxidants When the body uses oxygen or
breaks down certain fats or proteins as a normal
part of metabolism, it gives rise to substances
called free radicals
• free radical An electron-seeking compound that
can react with fats, proteins, and DNA, damaging
cell membranes and mutating genes in its search
for electrons; produced through chemical
reactions in the body and by exposure to
environmental factors such as sunlight and
tobacco smoke.
Daily exercise and weight control