Role of Protein
A protein-restricted diet has to be combined with adequate calorie
intake. Other recent studies have shown that complete fasting can be
just as harmful as protein feeding since an increased breakdown of body
proteins occurs releasing urea and potassium which must be eliminated by
the kidneys. To offset this effect of complete fasting,
a diet with adequate amounts
of carbohydrates and fats
should be used for its "protein-sparing action." (Such a diet will be
fully discussed later on in this article.)
Protein in food is broken down during digestion into amino acids. These amino acids are then taken by the individual cells and rebuilt into the proteins needed for the cell's particular type of tissue. (A kidney cell, for example, will use the amino acids to rebuild kidney tissue.) This is known as protein anabolism. At the same time, protein and amino acids which the body can no longer use or no longer needs are disintegrated (protein catabolism} and eliminated. Most of the end products of protein catabolism are eliminated in the urine as nitrogenous substances, usually, about 87% in the form of urea.
The Protein See-Saw
Now, every gram of protein contains on the average .16 grams of nitrogen. A person is said to be in protein (or nitrogen) balance when he eliminates the same amount of nitrogen that he takes in. In other words, if you consumed 16 grams of nitrogen (from the protein) in your meals, you would have to eliminate 16 grams of nitrogen to be in protein balance. If you were to eliminate less than this, you would be said to be in positive protein balance. (This happens during periods of growth or during pregnancy when the body is using more protein than what it usually needs for "wear and tear" to build up body tissue.) However, if you were to eliminate more nitrogen than what you take in the food, you would be said to be in negative protein balance for you would be using up some of the body protein as well as the food protein. (This can happen during a fever, or in undernutrition or starvation. )
Obviously, if this state of affairs were to continue for long, you would eventually die for you would use up all your body protein. But long before this would happen, you would find that you had lost all your resistance to infection (your body uses protein to form anti-bodies)
and to shock and the time your body needed for healing wounds, infections and other tissue injuries would be much greater. Worse, still, your liver would be very susceptible to damage.
So that in cases of chronic kidney disease, the protein problem is a difficult one. Often, because the sick kidney may allow the protein molecule to pass through its membranes (normally, it's too large to pass through healthy kidney membranes) large amounts of protein are lost in the urine. Such a state of "proteinuria" (also known as albumin-uria) is one of the first signs of kidney disease.
Ehret thought that the protein was excreted in the urine because the body could not take it. More recently, Drs. Stieglitz and Kimble have stated that proteinuria might "well be a defense mechanism, even in nephritis." They believe that the protein in the blood might combine with toxins so as to make them harmless and be able to excrete them via the kidneys.
But, whatever the reason
for the proteinuria, if it is excessive and continued for long, it can result in a severe protein deficiency unless the amount
lost in the urine is made good by the diet.
So, though you must maintain protein balance, if you have weak kidneys you must be sure to make up protein losses without overstraining your kidneys past the point where they can no longer excrete urea.
To do this, you must consume the very minimum amount of protein necessary to maintain protein balance. You can determine this minimum by taking a protein-free but otherwise adequate diet for a few days and then adding protein in small amounts each day until
your urinalysis shows that you have reached protein equilibrium. This figure varies from person to person. Different investigators have arrived at figures which range from 1/3 to 2/3 grams of protein per kilogram of body weight. As you can see, they are rather below the minimum allowances recommended by the National Research Council. Nonetheless, the textbook, "Human Physiology" edited by Nobel prize winner, Ber-nardo Houssay, notes:
"Careful observations made on human subjects have shown that it is possible to keep in excellent health with small amounts, e.g., 40 to 50 gm. daily (Chit-tenden), 35 gm. (Sherman) and even 22 gm. (Hinhede)."
The National Research Council recommends approximately twice the true physiological minimum requirements to provide a "margin of safety," so as to prevent deficiencies due to the ingestion of poor-quality protein (that is, protein which does not contain all of the eight essential amino acids or does not contain them all in adequate amounts).
You can take that this does not happen by eating a daily diet which contains 35 grams, more or less, of high quality protein and/or poor-quality proteins which supplement each other (such as, for example, do grains and legumes). The table lists the minimum and the recommended requirements of the eight essential amino acids, while the one on lists the amino acid content of the more common protein foods. Using these two tables you will not find it difficult to plan a protein-balanced diet which will not overstrain your kidneys.
Heart Disease Factor
This over-concentration or proteins is more than only dangerous to the weakened kidneys, as Ehret, Kuhne, etc. pointed out long ago and as statistics on cardiovascular and kidney diseases are bearing out. At the annual meeting of the American Society for Clinical Investigation (May 6th, 1957) a group of research workers from the University of Pittsburgh showed evidence that animal fats—as is so widely accepted today— were not the only factors in high blood cholesterol levels. High protein diets also raised the levels.
Excessive protein intake, then, can very easily be a cause of hardening of the arteries and, thus, of the high blood pressure which is nearly always present in cases of nephritis.
Let's summarize what we've discussed before.
Your kidneys are remarkable in their ability to take punishment. Nature has endowed them with a capacity for work approximately 400% more than what they need under normal circumstances.
Nature in her wisdom has provided the same excess reserve for the heart, liver, lungs, etc. because she knows that should one of these vital organs fail, the body cannot live.
But it's this very excess reserve that makes people foolhardy. Like spendthrifts they waste their golden assets until they are bankrupt. And because of this very excess, kidney disease is silent—and treacherous. The spendthrift patient does not realize his reserves are vanishing until one day they are all depleted—and then it's too late. So, if you've had a history of kidney troubles, take stock of yourself now—you may be near the point of no return.
Your kidneys will heal themselves—if you give them the chance. And to give them this chance you must provide them with two things: rest and the tools they can use to regenerate themselves.
This type of diet is one which is low in proteins by present day comparisons, but which is nonetheless, adequate.
It has been shown conclusively that the greater the amount of protein in the diet, the greater the amount of work for the kidneys which must excrete the toxic and acid end-products of protein metabolism. Studies have also shown that the average diet of even the poorest income group in the United States over-concentrates on proteins by as much as 200% to 300 c/f above the recommended minimum daily requirements which are already high in themselves!
On the other hand, we cannot cut down so much on our protein intake that we do so at the expense of our over-all health. Proteins are essential for normal wear and tear; for the replacement of blood plasma and hemoglobin, for tfae formation of antibodies, etc. The tables which appear at the end of the page, will help you navigate between this devil and this deep blue sea.
Essential Amino Acid Content of Some Foods
* Soy bean amino acid content is expressed as percentage in 100 gms of crude protein so that values are comparatively low
Amino Acid Requirements