Are the basic materials of every body cell.
Body cells are constantly wearing out. As a result, they are continuously in need of replacement Of the six nutrients group, only proteins can make new cells rebuild tissue. By the age of 4 years, body protein content reaches the adult level of about 18% of body weight. An adequate supply of proteins in the daily diet is essential for the maintenance of health. The word protein is a Greek derivation and means “of first importance”.
Contains carbon, hydrogen and oxygen but in different proportions. Most important nutrient group because it contains NITROGEN and some sulfur. Composed of chemical compounds called Amino acids.
Amino acids are sometimes called the building blocks of protein because they are combined to form the thousands of proteins in the human body. Hereditary determines the specific types of proteins within each person. Classification
There are 20 amino acids but only 9 are considered essential to human Essential amino acids are necessary for normal growth and development and must be provided in the diet Proteins containing all the essential amino acids are high biologic value and are called Complete proteins (high quality) The non-essential amino acids can be produced in the body if an adequate supply of amino nitrogen is provided in the diet. Essential Amino Acids
Non-Essentail Amino Acids
4. Aspartic acid
7. Glutamic acid
Incomplete Proteins (low quality)
are those that lack one or more of essential amino acids.
cannot build tissue without the help of other proteins.
The value of each is increased when it is eaten in combination with another incomplete protein, not necessary at the same meal but during the same day. In this way, one incomplete protein food can provide the essential amino acids the other lacks. The combination may thereby provide all nine essential amino acids. When this occurs, the proteins are called Complementary proteins. Gelatin is the only protein from an animal source that is an incomplete. Examples of Complementary Protein Foods
1. Corn and beans
2. Rice and beans
3. Bread and peanut butter
4. Bread and split pea soup
5. Bread and cheese
6. Bread and baked beans
7. Macaroni and cheese
8. Cereal and milk
Proteins are found in both animal and plant foods
The animal food sources provide the highest quality or complete proteins. Include meats, fish, poultry, eggs, milk and cheese
Despite the high biologic value of proteins from animal food sources, they also provide saturated fats and cholesterol. Complete proteins should be carefully selected from low-fat animal foods such as fish, lean meats, and low fat dairy products. Eggs should be limited to two or three a week
Proteins found in plant foods are incomplete proteins and are of the lower quality than those found in the animal foods. Even so, plant foods are important sources of protein. Ex.: Corn, grains, nuts, sunflower seeds, sesame seeds, and legumes such as soybeans, navy beans, pinto beans, split peas, chickpeas and peanuts Plant proteins can be used to produce textured soy protein and tofu also called analogues. Meat alternatives (analogues) made from soybeans contain soy protein and other ingredients mixed together to stimulate various kinds of meat. Meat alternatives may be canned, dried or frozen
Analogues are excellent sources of protein, iron, and B vitamins. Tofu is a soft cheese-like food made from soy milk
Tofu is a bland product that easily absorbs flavors of other ingredients with which it is cooked. Tofu is rich in high quality proteins and B vitamins and is low in sodium. Textured soy protein and tofu are both economical and nutritious...
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