Protein
The word protein originated from a Greek word proteios meaning “to hold first place”
or “is of prime importance”. Mulder a Dutch chemist, proposed the name in 1840 and
until now, the word is used due to its unique function of building and repairing cells
and other specialized roles in metabolism that cannot be accomplished or performed by
other nutrients.
Proteins have the elements: carbon, hydrogen and oxygen. However, it is the nitrogen
content of protein that distinguishes it from the other organic compounds.
essential Semi essential Non-Essential
Histidine Arginine Glutamic Acid
Isoleucine Tyrosine Aspartic Acid
Leucine Cystine Alanine
Lysine Glycine Proline
Methionine Serine Norleucine
Phenylalanine Citrulline
Threonine Hydroxyglycine
Hydroxyproloine
Tryptophan
Valine
1. According to Composition
1. Fibrous proteins-consist of long coiled or folded chains of amino acids bound together in
parallel line. They are found in the protective tissues of animals such as skin, hair, tendons,
feathers, scales and fons of fish. These are insoluble in water and are able to provide support for
cells and tissues.
Keratin- chief protein in hair
Collagen-connective tissue, in tendons and bone matrices Fibrin-of a blood clot
Myosin-of muscle
Elastin-in blood vessel walls
2. Globular proteins- are proteins wherein its structure is coiled and tightly wounded and is
relatively soluble in water.
Casein –in milk and cheese Albumin in egg whites and milk Globulin-in red blood cells
2. According to Nutritional quality
a. Complete protein- contains all essential A.A.
-high biological protein
-sufficient for growth and can maintain life (All Animal Sources)
2. Partially complete protein- can maintain life but cannot support growth (wheat-gliadin,
Legumes- legumin)
Functions of Protein:
1. Builds and repair body tissues
2. Important for growth
3. Source of Energy
4. Regulator of body processes
5. Body building (enzymes, hormones, antibodies, cells)
Protein Malnutrition
Clinical Manifestations:
-weight loss
-malaise (feeling of discomfort or of uneasiness)
-dry and scaly skin
-Hyperproteinemia
-Growth retardation
-General weakness
-Reduce resistance to infection
-nutritional edema (swelling in the body)
-pallor (Paleness especially of the face)
Protein Energy Malnutrition- Protein Calorie Malnutrition
Marasmus Kwashiorkor
A. Age group 0-2 years old Usually infants 1-3 years old
Failure to breastfeed Usually older children
Substitution of breast milk Weaning child with starchy
B. Cause
with dirty and diluted milk diet
formulas (rice,corn,bananas,tubers)
without high protein foods
Milk,eggs,fish and meat
C. Important features Wasting(Weak)
General Appearance Edema or bloated Bloated
Skin and bones appearance lower legs
Old Man’s face
Factors Affecting Protein Utilization
A. Immobility-causes negative balance particularly in bedridden persons (geriatrics)
- Inactivity and inadequate intake of food
B. Emotional Stress- fear, worry, anxiety and anger)
-increase secretion of adrenaline results to negative nitrogen balance
C. Lack of Calorie Intake
D. Inborn Errors of Metabolism-due to lack of enzymes needed for protein utilization
Factors Affecting Protein Requirements
1. Body size
2. Effect of Growth
3. Effect of Pregnancy
4. Effect of Aging
Ways of Improving Protein Quality
To increase the nutritive value of protein foods here are the ways on how to increase its value.
1. Fortification- refers to the addition of amino acids in desirable levels so that food
contains more than what originally exists(Lysine added to bread)
2. Enrichment-to restore what was lost during the milling process by adding an amino
acid according to Food and Drugs standard(Lysine to cerelac)
3. Supplementation-refers to the addition of protein rich foods to regular diet so as to
increase total protein content and improve its standards.(high protein milk given in
addition to lugao or fruits and vegetables)
4. Complementation-refers to the combination of food proteins such that one lacking in an
essential amino acids is provided by another rich in that amino acid.(rice and monggo,
soybean and wheat, soybean and nuts, cottonseed and corn, soybean and corn, soybean
and red kidney beans.
Your rich sources of your protein are:
Animal Sources:
Meat (lean), internal organs (liver, heart, kidney, etc.)
Chicken, eggs
Fish, shellfish
Milk and milk products
Plant Sources:
Munggo and other dried beans (garbanzos, tokwa, etc.)
Nuts (peanuts, etc.)
Recommended Daily Serving for a Normal Adult:
Fish- 1 ¾-2 servings,
one serving………….= 2 medium-sized fish, about 16cm long or 55-60 gm. each as purchased
or about 3cm cube cooked lean meat, 30 gm or 2 medium sized eggs, 50 gms, each or 11/2 cups
of cooked dried beans and Dried beans/nuts…………………1/2 cup, cooked and
eggs………………………………..1/2 piece
