Interest approach: A number of years ago my grandfather and grandmother bought a Model T Ford. It did good service for some time, but one fateful day the old Ford refused to go. A garageman was called, and the Ford was towed in. Investigation revealed the fact that a part of the motor was worn out, and only upon its replacement could the machine be made to go. I can visualize grandmother making a remark something like this: "John, did you ever get this car checked over like I told you to?"
"Why, no, Mary, it has been doing fairly well, and the salesman said it didn't need any repairs. I didn't think it would need anything for a long time yet."
In grandmother's reply we find the salient thought of our lesson today : "John, don't you know that all running things require repairs?"
Just as an automobile requires repair, so the human body requires certain kinds of foods to keep the delicate mechanism in repair. Foods can be eaten to fill, but not all foods function in building body tissue and keeping it in repair. The class of foods which does this important work is called protein.
I. WHY WE NEED PROTEIN.
- Integral part of every cell in the body.
- Necessary for building of blood, formation of digestive juices (pepsin) and hormones (secretion of thyroid gland).
- Keeps muscle tissue renewed and repaired.
- Protein used up or lost from the body each day must be made up in our food.
II. WHAT IS PROTEIN?
I. Made up of many smaller simpler parts called amino acids, which in turn are made up of carbon, hydrogen, oxygen, nitrogen.
2. Protein is the only class of foods which contains nitrogen. This constituent makes it capable of building and repairing tissue.
III. KINDS OF PROTEINS.
1. Many kinds of proteins—each one made up from a certain combination of amino acids. Illustration: show how from twenty-six letters in the alphabet many words and sentences can be made. When a protein is digested, it is broken down into individual parts—amino acids. When a body
protein is built up, a combination of amino acids is possible that is different from that in the digested protein. At least eight amino acids, essential for building or repairing body tissues.
2.Complete proteins—contain all eight of the essential amino acids.
3.Incomplete proteins—lacking in one or more of the essential amino acids, or containing them in very small amounts.
4.The amino acid make-up of a protein determines the nutritional value of that protein.
Example : Casein of milk contains all eight essential amino acids ; therefore a protein of high quality. Gelatin, one of the proteins of animal origin, lacking in at least two of the essential amino acids, and therefore a protein of poorer quality.
IV. SOURCES OF PROTEINS.
I. Most foods contain some protein.
a. Milk, cheese, eggs, wheat germ, dried legumes, nuts, are good sources for vegetarians.
b. Cereals are fair sources.
c. Fresh fruits and vegetables contain small amounts.
2. Most foods contain more than one kind of protein.
a. Milk contains casein and lactalbuminboth complete proteins.
b. Wheat contains five different kinds of proteins, only two of which are complete. The quantities in which they occur make the wheat kernel as a whole deficient in the quantity of essential amino acids. A small amount of milk added to wheat will supply the deficient amino acids, thus making this combination a complete source of protein.
3. Select protein foods from various sources, both of complete and incomplete type, making the possibility greater of getting all essential amino acids.
V. How MUCH PROTEIN NECESSARY?
1.Quantity of protein needed by an adult de-
pends on his size, not upon his activity.
2.Growing child requires from one and a half to two times as much protein per unit of body weight as adult.
3.Standard protein requirement set by nutritionists, one gram per kilogram of body weight, or about one-half gram per pound of body weight.
Example: Person weighing 130 pounds needs about 65 grams of protein daily. One's protein intake may be calculated by consulting tables showing protein content of servings of foods.
4.Food pattern for a day. Protein needs of average-sized adult. Check your day's protein intake.
(See PDF for daily intake)
VI. RESULTS OF INSUFFICIENT PROTEIN.
1. Tissue degeneration.
2.Poor physical tone.
3.Lowered resistance to disease.
4.Severe protein deficiency results in hunger swelling.
5.Premature old age.
VII. CAN WE GET TOO MUCH PROTEIN?
I. A lacto-ovo vegetarian diet properly balanced, with liberal intake of fruits and vegetables, will not be too high in protein.
2. Diet containing generous amounts of meat likely to be overbalanced from standpoint of protein.
Summary and Application
1. Our bodies need constant renewal, or repair, to be kept in best running condition. -
2. Body suffers if it does not get enough protein.
3. Proteins are repair foods.
4. Many kinds of proteins.
5. Proteins from different sources differ in quality.
6. We should get protein from many different sources.
7. Taking more protein than the body needs is wasteful.
8. Based on your normal weight, determine your protein requirement,
9. Check your protein intake with your requirement.
Illustrative Material
I. Small wooden blocks may be used to illustrate the amino acids, which may be built up to illustrate a protein. The eight essential amino acids should be colored differently from the rest of the blocks.
2.Large chart or poster showing grams of protein in servings of a few of most common foods.
3.Display actual foods indicating actual protein content: Soybeans, round steak, eggs, milk, cottage cheese, peanuts may be arranged on a table in portions providing ten grams of protein each. The cost of these ten-gram protein portions can be figured at local existing prices, thus showing the comparative costs of these foods as sources of protein.
