"IT IS A wonderful process that trans forms the food into blood and uses this blood to build up the varied parts of the body." —The Ministry of Healing, p. 295. Ellen White wrote these words at a time when it was thought that tissues "wear and tear." There was no idea of "the dynamic equilibrium of body constituents," yet she advanced some bold theories that hard work and dedication have since confirmed.
"A wonderful process"—this is especially true of proteins, those substances that are found in all the foods we eat and that help us to grow and to maintain our body tissues. The word protein itself has a connotation of essentiality. Coined from the Greek word proteios, by Mulder in 1839, it meant "to take first place." Since then, it has come to be understood that not only proteins but all the essential nutrients take first place.
Structurally, all proteins are made of about twenty amino acids. These building blocks are linked together in a sequence that is specific for each protein. One protein may be composed of hundreds of amino-acid units. Thus, proteins may have different functions according to their amino-acid makeup. Our bodies cannot manufacture eight of the twenty amino acids. The foods we eat must supply them. Thus, the quality of a protein is measured by the kind and amounts of the essential amino acids it contains.
How does this "wonderful process," the integration of a food into blood and tissue, take place? It is not simple. There are yet unknown details. But the overall pathway is known—the trans formation of food into usable particles that can enter the body and, transported in the bloodstream, nourish and become part of every cell.
It is a step-by-step process. In the mouth the food is mashed by the teeth, which are aided by the tongue. With saliva providing the moisture, it is kneaded to a semisolid paste—the bolus. Pushed by the tongue against the pal ate, the bolus is forced into the open pharynx with muscles coming into play in such a way that the mass is propelled down the esophagus into the stomach.
Once the food is in the stomach, a churning, mixing, milling, and pushing takes place so that some constituents can be separated. The juice secreted by the stomach lining contains hydrochloric acid and enzymes. Pepsin is the main enzyme that starts the breakdown of proteins into smaller protein sub-units, and the protein links are broken at certain sites, thus preparing the proteins for further enzyme attacks in the intestine. The work of digesting proteins merely begins in the stomach. This task is completed in the small intestine.
As the content of the stomach is emptied in small batches into the small intestine, a concerted effort immediately begins on all fronts. The pancreas sends its enzyme-rich juices into the small intestine. During the churning and propelling of intestinal content, enzymes unhinge or separate other specific links, starting from the outside or from the inside of the protein structure. This at tack proceeds seemingly without letup until the protein is broken down into its constituent amino acids. The resulting mixture little resembles the original protein. Consequently, the protein has not only lost its identity but its function and its form. At this point, whether or not the original source of the protein was flesh meat or plant makes no difference at all. What is important is that the essential amino acids the body needs are there.
Then the passage of amino acids across the cell membrane of the small intestine begins. They cannot freely cross that obstacle by themselves, but there are a few mechanisms called carrier systems that actively move specific amino acids across into the cells that make up the lining of the small intestine.
The lining cells use some amino acids for their own needs, but the greater portion proceed into the blood through vessels that take nutrients from the intestines to the liver.
The liver, like a great factory, uses the incoming amino acids to form proteins for its own refinements or for manufacturing such export products as blood albumin. It also strips some amino acids of their nitrogen and uses the skeleton for making glucose. The nitrogen is recycled to form urea, an excretion product, or it is incorporated into a suitable carbon skeleton to form other amino acids. However, the most important function of the liver is the regulation of the flow of amino acids into the bloodstream so that a certain level is constantly maintained.
The amino acids in the bloodstream reach the most remote cells of the body. This free amino-acid pool, or reservoir, is maintained not only by the liver but also by the constant give-and-take be tween the tissues and the bloodstream in a process called "the dynamic equilibrium of body constituents."
Ellen White explains it this way: "There is a constant breaking down of the tissues of the body; every movement of every organ involves waste, and this waste is repaired from our food. Each organ of the body requires its share of nutrition." —Ibid.
The Cell Likened to an Estate
When amino acids enter a body cell, the business of building body protein really begins. If, in our imagination, we enlarge a cell to the size of a house and its surrounding gardens, many features become clear. The large surrounding gardens you visualize represent the cytoplasm, in the middle of which stands the house (nucleus) and many other smaller buildings where work is done. The nucleus guards the information of the cell, thus maintaining its identity and integrity. In it are 23 pair of chromosomes that contain valuable coded messages situated in a twisted double-stranded structure known as DNA (deoxyribonucleic acid). Located along this strand are the genes that have the key to our inheritance. This information can be transcribed in a coded message to a mirror-image strand, the RNA (ribonucleic acid). Thus the coded message in RNA will tell what kind of protein will be formed and for what purpose.
In the gardens there are various smaller structures called ribosomes along covered paths (endoplasmic reticulum) that crisscross the property. Some paths end in flat structures (the Golgi apparatus) beside the nucleus. The messenger RNA (the strand with the coded message formed in the nucleus) lines the ribosomes. Here protein molecules are assembled.
Meanwhile the amino acids in the garden (cytoplasm) wait for a special guide to take them to the ribosomes. The amino acids are first groomed (activated) so that they can be picked up more easily by a "guide" (transfer RNA). There is at least one guide for each amino acid, and each guide easily recognizes its own charge. Once together, the guide and the amino acid search for the specific space where that particular amino acid is needed. Then carefully the amino acid is placed in the allotted spot. There can be no error. Just one malfunction and the protein would be faulty and unable to perform its function. The guide has to read his cue accurately.
And so the protein strand grows with the incorporation of each of the amino acids in the predesigned model to form a chain characteristic for that tissue or function. Some of the completed protein strands are used within the cells, and some are taken through the covered paths (endoplasmic reticulum) to the flattened structures (the Golgi) to be readied for their integration into other body tissues or body functions.
In writing of the process of trans forming food into blood and thus building up the varied parts of the body, Ellen White adds, "This process is going on continually, supplying with life and strength each nerve, muscle, and tissue."—Ibid. Thus the protein of food is incorporated into blood and tissue by a concerted effort of all the important machinery of the body.
When the body has no further use for a given protein molecule, it is broken down in a way we do not yet clearly understand. To return to our simile, there are incinerators in the garden for removing leftover or nonusable things. The cell also has some disposal units, the lysosomes, containing powerful enzymes to digest any nonusable protein and incorporate the resulting amino acids into the storage areas of the gar den. Thus, constantly, proteins are built up and degraded, a turnover that varies with each kind of protein. Proteins of the small intestine have a turnover of a few days, whereas collagen, from the connective tissue, has a turnover measured in years. But the process is continuous, according to the functions and needs of specific tissues.
How Much Protein Do We Need?
We should eat some protein daily. The requirement is not large. It is recommended that an average man (154 pounds) needs about 56 grams, whereas an average woman (128 pounds) needs about 46 grams. These amounts are more than adequate and can be met by a varied diet. "Grains, fruits, nuts, and vegetables constitute the diet chosen for us by our Creator. These foods, prepared in as simple and natural a manner as possible, are the most healthful and nourishing. They impart a strength, a power of endurance, and a vigor of intellect, that are not afforded by a more complex and stimulating diet." —Counsels on Diet and Foods, p. 81. Ellen White also adds: "In grains, fruits, vegetables, and nuts are to be found all the food elements we need." —Ibid., p. 92.
Although there is a continual breaking down and building up of body proteins, there is no increased need for protein for physical activity. The notion that an athlete has to eat a big red steak comes from custom or from a misconception about the role of protein. Von Liebig, in the past century, said that protein is needed for activity. Later, other scientists, including Voit and Pettenhoffer, found that nitrogen excretion is not increased during exercise, which indicates that protein is not involved in physical activity, as once was thought.
Ellen White put it this way: "It is a mistake to suppose that muscular strength depends on the use of animal food. The needs of the system can be better supplied, and more vigorous health can be enjoyed, without its use."—Ibid., p. 396.
The information explosion has touched every phase of knowledge. We now have more specific details than ever before about proteins and their utilization by the cells of the body. Such information only helps strengthen our confidence in the God-given principles of health reform.
