Proteins and Amino Acids
Protein is a nutrient that is needed daily by the body. Protein has many functions:
Protein is a nutrient that is needed daily by the body. Protein has many functions:
- It helps to build, repair, and maintain body cells and tissues like your skin, muscles, organs, blood, and even bones.
- It also forms enzymes and hormones that enable your body to function normally. Enzymes enable chemical reactions to take place in your body. Hormones signal the appropriate enzymes to start working on what the body needs.
- Proteins as antibodies protect you from disease-carrying bacteria and viruses.
- Proteins help regulate the quantity of fluids in the compartments of the body to maintain your fluid balance. Protein also controls the composition of the body fluids.
- Proteins control your body’s acid-base balance. Normal processes of the body continually produce acids and their opposite, bases, which must be carried by the blood to the excretion organs. The blood must do this without allowing its own acid-base balance to be affected. The proteins in your blood accomplish this task.
- Only protein can perform all the functions described above. But it will be sacrificed to provide needed calories if insufficient fat and carbohydrates foods are not eaten. The body’s top-priority need is energy, and protein is a source of calories (4 calories per gram). As with all foods, if you eat more protein than you need, the extra will be stored as fat.
The Purpose of Amino Acids
During digestion, protein is crushed and mixed with saliva in the mouth. It then enters the stomach and comes in contact with very strong acid. This acid helps to uncoil the protein’s tangled strands. Stomach enzymes attack the protein bonds, breaking apart the protein strands into smaller pieces. The protein pieces enter the small intestine where the next team of enzymes accomplishes the final breakdown of the protein strands into free amino acids. The cells of the small intestine release the amino acids into the bloodstream.
Once the amino acids are circulating in the blood stream they are available to be taken up by any cell of the body. Amino acids combine with other amino acids to form the specific proteins needed by the body.
The many different proteins in your body are all made up of these amino acid building blocks. There are a total of 20 different types of amino acids with nutritional significance. The body cells connect these building blocks to form each specific protein that is needed.
Nine amino acids are considered ESSENTIALYour body cannot make them, and your food choices must supply them. Their names may sound familiar: histamine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
The other amino acids are NONESSENTIALYour body can make them if you consume enough of the nine essential amino acids during the day. Believe it or not, 10,000 different proteins may exist in a single cell of your body. Each one requires a different arrangement of amino acids.
Sources of Protein
Meat, fish, poultry, eggs, milk, cheese, yogurt and soybeans provide all nine essential amino acids. For this reason, they are considered high quality or COMPLETE proteins.
Plant sources of protein include legumes (dried beans, peas, and lentils), nuts, and seeds. Grain products such as barley, wheat, millet, rye, as well as many vegetables have smaller amounts of protein. These plant sources are all INCOMPLETE proteins because they do not contain all of the nine essential amino acids that the body needs.
It is possible to still get your complete proteins without eating animal products. Luckily, the essential amino acids present in one plant food can “connect” with the essential amino acids in another plant food to form a complete protein. This is the principle of a healthy vegetarian diet. There is no need for combining specific foods at each meal, as once thought. Your body can make its own complete proteins if you eat a variety of plant foods and eat enough calories throughout the day.
How Much is Enough
Health organizations recommend limiting your protein intake to 10-35% of your total calorie needs. My suggestion would be to try to shoot for 20-25% of your daily caloric intake as protein, unless there is an underlying health reason you need to limit your protein intake. In most cases, this example protein intake could still be considered healthy if it ranged from 50 grams (10% of intake) to 175 grams (35%).
To give you an idea of the amount of protein you can find in certain foods, check out the following list:
- 1 cup milk…8 grams
- 1 ounce cheese…7 grams
- 1 ounce meat…7 grams
- 1 egg…6 grams
- ½ cup legumes…7 grams
- 2 tablespoons peanut butter…8 grams
- ¼ cup nuts…6 grams
- ½ cup cooked non-starchy vegetable…2 grams
- 1 serving of grain (1 slice bread, ½ bun, 1 c. dry cereal, 1 small muffin)…3 grams
The power of protein is easy to achieve. Obviously, with the great availability of animal foods and nutritious grains and vegetables, most of us have little trouble meeting and probably exceeding our protein needs
