Note
Final Exam-please check final schedule
Ms. Natasha Harrietha, a dietitian, will give a
lecture on Thursday, 19 March from 10:05-10:55
am. You will be responsible for the material she
presents.
Atlantic Superstore Tour-Sydney River -24 March10 am
Lecture 24 – 10 March 2016
Proteins
Proteins
Comes from the Greek word protos meaning of
prime importance
What are they?
-chains of amino acids
-an amino acid is an organic acid with a
side group and an NH2 group attached
Functions of proteins in the body
-structure
-hair, nails, cells
-mechanical functions
motor proteins
-eg contractile proteins in
muscle
Functions of proteins in the body
-enzymes
-aid in reactions- make the reactions
go faster
-hormones
-signals to cells
-eg insulin
-antibodies
-help fight infection
Functions of proteins in the body
-fluid balance
-osmotic influence
-acid base balance
-charge on certain proteins affects pH
-channels
e.g.-move ions into and out of cells
Functions of proteins in the body
-pumps
-move substances across cell wall by use of
energy
-transport
-eg -lipoproteins transport fat in bloodstream
-carry fat soluble vitamins
-source of energy and glucose
-when protein is broken down it gives
energy
Functions of proteins in the body
-used to make neurotransmitters
Digestion of protein
-stomach acid
-denatures-straightens out proteins –readies
them for small intestine digestion of
proteins
-small intestine- enzymes attack proteins and
make them into amino acids
Absorption of protein
Amino acids moved across intestinal wall into
blood
Transport of protein
No special needed-the amino acids are water
soluble
Metabolism
Individual amino acids assembled into proteins
humans need
How are proteins made in the body?
-remember protein in is not protein out
-proteins are made from copies of DNA
Excretion
Proteins are broken down into amino acids and
then amino acids are further broken down- urea
is one product of amino acid breakdown, urea
and other components of protein breakdown are
put in the urine and excreted
Nitrogen balance
-positive nitrogen balance- more protein being
made than broken down –pregnant female
-zero nitrogen balance- protein is being made as
fast as it is being broken down-healthy person
-negative nitrogen balance- protein is being broken
down faster than it is being made eg illness
Recommended intake of protein
Infants 0-6 months 2.2 g/kg body weight/day
Children
1-1.6 g/kg body weight/day
Adults
0.8 g/kg body weight/day
Seniors
0.8 g/kg body weight/day
-For all about 15-20 % of daily energy intake
-Must be high quality (complete) protein
Protein quality
Complete proteins –correct balance of essential
amino acids
Definitions of two types of amino acids
-essential and non-essential
Most animal proteins are complete
Many plant proteins are incomplete- exception
soybean protein
Complementarity
Beans and rice
Beans and corn
Rice and lentils
Pasta and beans
Peanut butter on bread
Estimating protein intake
Food labels will allow you to do this
Following Canada’s food guide will allow you to
estimate this
Vegetarianism
Various types of diets in vegetarianism-progressive
risk of inadequate protein intake going from
omnivores to fruitarians
Health risks
Vegans-low in iron, calcium, zinc, vitamin D
and B6 and B12
-higher intakes of oxalates
Fruitarian-limited in many essential nutrients
Supplements of deficient nutrients frequently
required for vegans and fruitarians
Protein deficiencies
Protein energy malnutrition (PEM)
Marasmus
Wasting- skin and bones look
Not enough energy or protein
Kwashiokor
Evil spirit that affects first child
when the second one is born
Enough energy not enough protein
Swollen belly appearance
Excess protein intake
Risk of cancer, heart disease and
osteoporosis and renal failure