The word ‘protein' was created by Dutch Chemist, Geradus Mulder, in 1838. It came from the Greek word ‘protos,' meaning "of prime importance."
The human body, after water, is largely made up of protein. When we eat protein rich foods, digestive juices in the stomach and intestine break the protein down into what are called amino acids. These amino acids then enter the blood stream and travel to the body's cells, where they are remade into 10,000 different proteins needed by the body.
The Function of Protein
The body uses protein for growth, and to maintain and repair bone, muscle, connective tissue, internal organs, skin and blood. Protein is the main component of our organs, muscles, and the glands of the immune system. Every living body cell contains protein; and all body fluids, except urine and bile, contain protein. Cardiac muscle is built with protein. Hormones, antibodies, and the enzymes that regulate the body's chemical reactions, are all made of protein. Protein is used to make hemoglobin, which is part of red blood cells, and carries oxygen to every part of the body. Without the right protein, cuts won't heal, and blood won't clot properly.
Protein Sources from Foods
A complete protein is made up of 22 amino acids. Our body can make 13 of these naturally; these are called the nonessential amino acids. The other nine amino acids are called the essential amino acids, because it is essential that we get them from the foods we eat. In this way protein is divided into the two categories: Nonessential and essential.
Of the essential amino acids (the ones we must get from the foods we eat), some are complete proteins and some are incomplete proteins.
Animal proteins from meat, fish, poultry, milk, eggs, and cheese are complete proteins because they contain all nine of the essential amino acids.
Plant proteins that come from grains, fruits, vegetables, beans, and nuts, are incomplete proteins because they are low, or lacking, in one or more of the nine essential amino acids.
Strict vegetarians (vegans) who do not eat meat, eggs, or dairy products, can get an adequate supply of protein from the plant foods they do eat as long as they eat a wide variety of foods, in sufficient quantity, to sustain a normal weight.
Dietary Recommendations
The average adult needs 50-65 grams of protein a day, or about seven grams of protein for every 20 pounds of body weight. A balanced diet provides most Americans with adequate protein.
Typical Sources and Average Grams of Protein
* Lean meat, poultry or fish - one four ounce serving: 25-35 grams
* Cooked beans or lentils - one cup serving: about 18 grams
* Low fat cottage cheese - one cup serving: about 28 grams
* Peanut butter - two tablespoons: about 8 grams
* Whole wheat bread - one slice: 3 to 6 grams
* Vegetables - one serving: 1 to 3 grams
* Low-fat Milk - one cup: 8 grams
* Solid Cheese - two ounces: about 16 grams
The Role Calcium Plays
When protein is eaten, acids are released into the body. These acids are neutralized with calcium. When a diet is high in protein, more calcium is needed to neutralize the additional acid. If enough calcium is not consumed, some of the calcium needed to neutralize the acids may be pulled from the bones. Following a high protein diet for an extended period of time could weaken the bones.
Fat in Protein
It is important to pay attention to the fat content in the protein you eat. A six-ounce broiled Porterhouse steak will provide about 38 grams of protein, but will also provide 44 grams of fat, and 16 of them will be saturated fat. This is almost three-quarters of the recommended daily intake for saturated fat. The same quantity of salmon will provide 34 grams of protein, with only 18 grams of fat, and only four of those will be saturated fat. A cup of cooked lentils provides 18 grams of protein, and under one gram of fat.
Soy's Role as a Protein Replacement
The American Heart Association has stated that soy protein has little direct effect on cholesterol. It has said, however, that soy foods are good for the heart and blood vessels because they usually replace less healthful choices, like red meat. Soy contains polyunsaturated fat, fiber, vitamins, minerals, and is low in saturated fat.
Some studies have suggested that concentrated supplements of soy proteins may stimulate the growth of breast cancer cells. Large studies, now underway, should offer better information regarding soy and breast cancer risk.
Protein and Weight Control
A diet that is low in saturated and trans fats, but high in protein, may decrease the amount of triglycerides in the blood, and be good for the heart.
Fat can be shed more quickly on a high-protein, low-carb diet than on a low-fat, high-carbohydrate diet. There are several reasons for this. First of all, protein foods empty more slowly from the stomach. This means you will feel fuller longer and possibly have to eat less often. Also, protein has a gentle, steady effect on blood sugar levels as opposed to the steep rise that comes from a meal high in carbohydrates. Finally, the body uses more energy to digest protein than it uses to digest fats or carbohydrates in our diet.
Side Effects
The typical American diet provides adequate protein. One government study, however, did estimate that as many as 50% of elderly people, living in nursing homes in the United States, suffer from protein-calorie malnutrition.
Millions of people in underdeveloped countries around the world are unable to get enough protein from their diets. This causes a form of malnutrition characterized by growth failure, loss of muscle mass, decreased immunity, weakening of the heart and respiratory system, and eventual death.
Diets too high in meat can lead to high cholesterol and gout. These diets can also put a strain on the kidneys.
End Note
There is no reason to go overboard with protein. Fruits, vegetables, and whole grains are also needed to provide fiber, vitamins, and minerals to a well-balanced diet. However, choosing high-protein foods, that are low in saturated fat, can help your heart and, with care, your waistline.
Hot Tip!
Capsaicin, which is the substance that makes hot peppers so "hot," is best neutralized by casein, the main protein found in milk!l