Carbohydrates, Fats and Proteins.ppt

nutrition

1. SMPA 108:
FOOD, NUTRITION AND HEALTH-
CARBOHYDRATE, FATS AND PROTEINS

2. Learning outcomes
Be able to
•enumerate the various food groups and their relevance
to nutrition
•Name three classes of nutrients that supply energy to the
body
•Describe the roles that carbohydrates, fats and proteins
play in the body

3. Types of nutrients
Macronutrients, body building or energy-yielding
nutrients: Carbohydrates, Proteins and Lipids.
Micronutrients or protective foods: Vitamins and minerals.

4. Energy from Foods
Calories (unit of energy): a measure of the amount of energy
transferred from food to the body.
Carbohydrate, fat, and protein -main sources of energy in a
diet.
The amount of energy a food provides depends on how much
carbohydrate, fat, and protein it contains.
–1 gram of CHO = 4 kilocalories (kcals) of energy.
–1 gram of protein = 4 kcals
–1 gram of fat yields 9 kcals.
Fat is more energy dense than carbohydrate or protein.

5. Essential nutrients
These nutrients are essential to human life. These essential nutrients
or indispensable nutrients need to be gotten from the diet.
The body cannot produce them or they cannot be produced in large
sufficient amounts for optimal health.
Different foods contain different nutrients in varying amounts.
Combinations, variety of foods provide a wider range of nutrients.

6. Source of nutrients
Green plants intercept sunlight through their leaves and
capture it within the chemical bonds of glucose.
Proteins, fats, and other carbohydrates are synthesized
from this simple carbohydrate to meet the needs of the
plant.

7. Cont’d
Animals and humans obtain these nutrients and the energy they
contain by consuming plants and the flesh of other animals.
The body makes use of the energy from dietary carbohydrates,
proteins, fats, and alcohol.
This energy is locked in chemical bonds within food and is released
through metabolism.

8. Classification of nutrients
oSix classes of nutrients
oCarbohydrates, fats, proteins (macronutrients)
oVitamins, minerals (micronutrients)
oWater
oMacro nutrients -constitute the bulk of the food we eat,
they provide energy and chemical building-blocks for
tissues.

9. CARBOHYDRATES (CHO)
•are made of carbon, hydrogenand oxygenwith the general
formula of C
m(H
2O)
n
•Major source of energy for the body’s functions.
•1 gram of carbohydrates contains 4 Calories.
•Daily CHO intake should be 45-65% of total calories.

10. Classification of Carbohydrates
A. Simple Carbohydrates (CHOs)
•1) Monosaccharide–simplest form of sugar.
–a) Glucose –blood sugar (grapes, corn and blood)
–b) Fructose –sweetest of simple sugar. (honey, fruits and vegetables).
–c) Galactose –not found in free foods. Galactose is gotten when the
lactose is broken down.
•Simple CHOs are water soluble, absorbed quickly in the
bloodstream and provide quick energy.

11. Classification of Carbohydrates
•2). Disaccharides: Made up of 2 monosaccharide units.
–a) Sucrose –ordinary table sugar (glucose + fructose)
–b) Lactose –milk sugar (glucose + galactose)
–c) Maltose –malt sugar (glucose + glucose). It is present in
germinating grains

12. Classification of Carbohydrates
B. Complex Carbohydrates (Polysaccharides)
–complex sugar
–Composed of many molecules of simple sugars
–e.g. Starches, Glycogen & most types of fibre
•Starches –are not water-soluble and require digestive enzymes called
amylasesto break them down. E.g.: rice, wheat, corn, carrots etc.
•Glycogen –the animal starch/ animal form of stored CHO
•Dextrins–they are produced by the breakdown of starch.

13. Classification of Carbohydrates
•Cellulose –Non-digestible by humans.
–composed of long unbranched glucose units
–lower the blood glucose level of people with diabetes.
–forms the main constituent of the cell wall in most plants
•Pectin –Sources from fruits and are often used as a base for jams &
jellies. Oranges, apples, grapes have high pectin content.
•Hemicellulose –indigestible,
–found in pectin, woody fibres, leaves, stems.

14. Functions of Carbohydrates
•Main source of energy for the body.
•Protein sparing action
•Cellulose stimulate peristaltic movement of the gastrointestinal tract.
Absorb water to give bulk to the intestines.
•Lactose encourage the growth of beneficial bacteria.
•Glucose is the sole source of energy in the brain.

15. Sources of Carbohydrates
•Whole grains
•Fruits e.g. Bananas, watermelon etc.
•Milk
•Sugar, sweets, honey

16. Common Diseases
•Overweight
•Diabetes
•Tooth Decay

17. Deficiency
•Ketosis –disease caused by lack of carbohydrates, in which
the acid level of the body is raised
•Protein-Energy Malnutrition (PEM)
–Marasmus –Caloric deficiency

18. Fats / lipids
-Are made up of carbon, hydrogen &
oxygen
-Most concentrated form of energy,
contains 9 Calories per gram fat
-Fats, oils, and waxes belong to the
group of naturally occurring
organic materials called lipids.
-Lipids are insoluble in water but
soluble in other organic solvents.

19. Fatty acids (FA)
•Fats consist of fatty acids with carbon chains of 4 -22
carbon molecules in the chain
•Hydrogen + FA →solid fatty acids during manufacturing of
some food products like vegetable spreads (i.e.
Hydrogenation).
•FA are carbon molecules with a methyl group at one end &
a carboxyl acid at the other end

20. Forms of Fatty Acids
•Saturated FA –fat molecules that have no double bonds
between carbon molecules because they are saturated with
hydrogen molecules. Usually solid at room temperature
–Considered as the type of fat that raises blood
cholesterol level and may lead to coronary heart disease
–Sources: butter, lard, fatty beef, poultry with skin,
cheese, cream, palm oil & coconut oil.

21. Forms of Fatty Acids
•UnsaturatedfattyAcids-haveatleastonedoublebond.
Theyareliquidsatroomtemperature.
–Monounsaturatedfattyacids(MFAs)containonlyone
doublebond.↓LDLChol.without–veeffectonHDL
•Sources:oliveoil,canolaoil,peanutoil,avocado,peanut
butter
–Polyunsaturatedfattyacids(PUFAs)containtwoor
moredoublebonds.
•Sources: sunflower oil, soybean, corn oil

23. Essential fatty acids -Omega-3 and omega-6 fatty acid
A polyunsaturated fatty acid that has its first double bond located
three carbons away from the methyl (CH
3) end is an omega-3 fatty
acid.
Whilst an omega-6 fatty acid is a polyunsaturated fatty acid that has
its first double bond located six carbons away from the methyl end.

24. ESSENTIAL FATTY ACIDS CONT’D
•Humans cannot synthesize ω-6 and ω-3 fatty acids.
•However they can desaturate and elongate linoleicacid(C18:2 ω-6)
to arachidonic acid (C20:4 ω-6), and alpha-linolenicacid(ALA)(CI8:3
ω-3) to Eicosapentaenoicacid (EPA) (C20:5 ω-3) and
Docosahexaenoic acid (DHA) (C22:6 ω-3).
•Thus linoleic and ALA acids are essential in the diet.

25. ESSENTIAL FATTY ACIDS CONT’D
The longer chain fatty acids (C20:4 etc.) are components of cell
membranes and are precursors of eicosanoids such as
prostaglandins (dilate arterioles and capillaries to reduce
blood pressure, thromboxanes (constricts blood vessels,
platelet aggregation), and leukotrienes (perform immune
related functions).

26. ESSENTIAL FATTY ACIDS CONT’D
BENEFICIAL EFFECTS OF OMEGA 3 FA
•Derivatives of ω-3fatty acids from diet (oily fishes) or fish oil
can have beneficial effects on some disease states
•Some of the beneficial effects are
–improved brain function during aging,
–protection from cardiovascular disease, arthritis,
inflammatory conditions, and neurologic disorders and
type 2 diabetes.

27. Functions Of Fat
•Energy source: Important source of calories to provide a continuous
supply of energy.
•Fat provides essential fatty acids
•Cushions vital organs such as kidney against injury
•Fat is a carrier for fat soluble vitamins (A,D,E,K)
•↑palatability by improving taste perception and appearance of food.
•Provides satiety and delays onset of hunger.

28. Sources of Omega 6 and Omega 3
•Omega 6 are from plant oil sources such as corn oil,
soyabean oil, sunflower oil and from nut and seeds.
•Omega 3 sources -From fatty fish such as salmon,
mackerel, tuna, walnut and flaxseed.
Walnut
Flaxseed

29. Cholesterol
•Cholesterol is a major component of all cell membranes. It is required
for synthesis of sex hormones, bile acids, and vitamin D. It is also a
precursor of steroid hormones.
•Cholesterol is endogenously produced in the body and is also
obtained through animal foods only
•But Cholesterol is a major factor in the development of heart
diseases
•Daily intake should not exceed 300mg/day

30. Types of cholesterol
•Lipoproteins –transport blood cholesterols
–Low Density Lipoprotein (LDL)
–High Density Lipoprotein (HDL)
•Low Density Lipoprotein Cholesterol (LDL-C) -A complex of lipids
and proteins, with greater amounts of lipid than protein, that
transports cholesterol in the blood. High levels are associated with
an increased risk of atherosclerosisand coronaryheartdisease.

31. CONT’D
•High Density Lipoprotein Cholesterol (HDL-C) -A complex of
lipids and proteins in approximately equal amounts that
functions as a transporter of cholesterol in the blood. High
levels are associated with a decreased risk of atherosclerosis
and coronary heart disease.

32. Source of Dietary Cholesterol
•Egg yolk, fish roes, mayonnaise and shell fish, whole milks,
cheese.
•Fat on meat, bacon, sausages, cream, ice cream, butter
and most commercially made cakes, biscuits and pastries.

34. PROTEINS
The building blocks of the body (16% of body weight in
adults is protein
• It contains the elements of carbon, hydrogen, oxygen and
nitrogen.
• Amino acids are the basic component of proteins

35. AMINO ACIDS
•Amino acids are known as the building blocks of protein.
•They perform many important functions such as:
–building cells,
–protecting the body from viruses or bacteria,
–repairing damaged tissue.
•There are 20 different amino acids. Amino acids are linked together
to form peptides, which are small chains of amino acids. The peptides
are then linked together to form larger proteins.

36. Types of Amino Acids
•Essential Amino Acids –are necessary for good health but cannot be
produced by the body and so must be supplied in the diet.
–Histidine, Isoleucine, Leucine,Lysine, Methionine, Phenylalanine,
Threonine, Tryptophan and Valine
•Non essential Amino acids: alanine,aspartic acid,asparagine,
glutamic acidandserine
•Conditionally essential:-they are only essential in specific
circumstances like in infancy
–arginine,cysteine,glycine,glutamine,proline, andtyrosine

37. Complete and Incomplete Protein
•Complete –contain all essential amino acid in sufficient
quantities to supply the body’s need
•Sources: proteins from animals. E.g. Meat (beef, pork, lamb), Eggs,
Milk, Diary products, Poultry (chicken, turkey, duck)and Fish
•Incomplete –those deficient in one or more essential
amino acids.
•Sources : Plant (grains, legumes, seeds and nuts)

38. Functions of Proteins
•Structural: protein is important for the structure of the body.
Structural tissues like the skin and muscle are made of protein. E.g. of
structural protein is collagen
•Transport: proteins act as transport carriers in the blood and body
fluids for many molecules and nutrients. E.g. Hb, lipoproteins
•Hormonal: proteins or amino acid chains serve as building blocks for
hormones production. E.g. insulin
•Enzymes: all enzymes are proteins
•Immune function: antibodies are protein molecules.
•Buffering function: they are involved in the maintenance of blood pH.
E.g albumin acts as a buffer

39. Deficiency
•PEM
•Burns
•Protein deficiency results in
–Poor wound healing
–Muscle wasting
–Stunted growth
–Susceptibility to infection
–oedema

40. END
OF
LECTURE