Proteins and Amino Acids
Proteins form a major part of our structure and are essential for all
biosynthetic functions. About 3% of the total body protein is recycled every day
(approximately 200 grams). In a healthy adult, net protein loss in a day may be
as low as 2 grams. This mean that protein intake of 2 grams per day can replace
losses. Dietary requirements for protein increase with activity, growth, and
protein losses, especially following injury or during illness. The average
American diet supplies 10-14% of total calories as protein. Protein digestion
and absorption are generally efficient. A minimum protein intake for a normal
adult is approximately 25 grams.
Loss of protein-tissues occurs with malnutrition, following surgery, injury,
and chronic illness. Adequate intake of energy molecules, both carbohydrate and
fats, is said to "spare protein", permitting a small protein intake to maintain
positive nitrogen balance. In metabolic studies, the total amount of nitrogen
intake is compared with the total excretion of nitrogen to assess protein
balance. Excess amino acids may be converted to fuel.
When amino acids are "burned" as a fuel, ammonia (NH3] is the waste
product. Ammonia must be carried to the liver, converted to urea and excreted by
the kidneys. One of the penalties of amino acid excess is ammonia excess, a
potential cause of body malfunction following a high protein meal. The blood
measurement of urea nitrogen (BUN) shows the balance between urea production by
the liver and excretion by the kidneys. The BUN rises in kidney failure and
serves as a measure of ammonia or nitrogen. In liver disease, reduced ability to
synthesize urea leads to ammonia accumulation.
Ammonia is neurotoxic and contributes to the syndrome of brain dysfunction in
liver failure, hepatic encephalopathy. Patients with reduced kidney or liver
function are required to restrict protein, since their ability to handle the
nitrogen waste of oxidized amino acids is limited. Fluctuating levels of ammonia
influences brain cell function; they should be considered whenever brain
function is abnormal. Some children are born with metabolic abnormalities in the
handling of amino acids and ammonia. They often present with malfunctioning
brains.
Amino Acid Requirements & Intolerances
The need for specific amino acids is difficult to determine. There is a wide
range of needs and tolerances among different individuals. Amino acids appear to
be relatively easy to obtain in adequate amounts, even on simple vegetarian
diets with no meat, fish, eggs, or milk, provided that different vegetables are
combined. Mixing a legume with a grain or with a tuber should provide a complete
amino acid mixture, as well as a good variety of vitamins and minerals.
Protein-deficiency anxiety is not well-founded in affluent countries. Some of
the non-essential AA's may become essential if their synthesis is blocked by
enzyme deficiencies. In order for protein synthesis to proceed, all the amino
acids must be supplied at the same time. Since we are mammals, all mammalian
proteins tend to have the same set of AAs as our own. Plant proteins may be
deficient in lysine, threonine, and tryptophan. Vegetables should be combined to
achieve a complete the AA set. Corn or maize, for example, is deficient in
lysine, although many years of corn-breeding research have produced hybrid corns
with increased lysine content. The substitution of the newer corn hybrids may
eliminate protein malnutrition where this is a staple plant.
Some patients on very limited diets (rice and a few vegetables alone, for
example) seem to ingest sufficient essential amino acids to remain well, at
least for several months even though their food may be deficient in essential
AAs. A minimal diet presents minimal problems to one's metabolism. A protein
deficient diet may be better tolerated than a protein excess diet.
We have thought a lot about the relationship between the food intake of
protein and the intakes of pure amino acids in one of our elemental nutrient
formulas. A naive assumption is that amino acid intake and protein intake are
the same. If you decide that a patient needs 75 Grams of protein per day and you
want to replace the protein with amino acids, you assume you have to give them
75 grams of amino acids. Not so.
If you look at RDA values for protein, you get the wrong idea that amino acid
intake level has to the same as protein intake but we believe that a daily
intake of 25 to 30 grams of free form amino acids will be adequate for most
people, most of the time. RDA protein values are crude approximations based on
food protein values. The proteins in foods have to be digested into dipeptides
and free amino acids before nutrients are available and protein digestion is
incomplete Some percentage of food protein is wasted in the digestive tract.
The trick is that if amino acids arrive in high concentrations, the liver is
obligated to destroy most of them; so that high protein intake is wasteful if
you want the amino acids to be utilized as protein building blocks and as
neurotransmitter substrates.
You have to know that the body recycles amino acids and becomes every
efficient when protein intake is low; the loss of amino acids can drop to about
2 grams per day. Amino acid proportioning is relevant to how
amino acids are admitted to cells and how they are utilized. The concept of
protein quality is used to express the idea that all the 9 essential amino acids
have to be present before any of them can be used to make proteins. Plants may
have incomplete amino acids sets, for example, and protein deficiency symptoms
can appear even when the protein intake is adequate.
On the positive side of the equation, if a completely available, precisely
engineered amino acid set is available, the total daily requirement is lower the
RDA values for food protein intake As a rule of thumb we recommend calculating
the RDA protein requirement in Grams and supplying 30 % to 50% of that value as
Alpha AAX, a blend of amino acids (available separately in Alpha AAX or combined
with other nutrients in Alpha ENF, Alpha PMX, and Alpha DMX.)
Inborn Errors Of Metabolism
Some amino acid abnormalities are overt and abnormal amounts of an
under-utilized amino acid or excessive amounts of an abnormal metabolite
accumulate in the blood and are excreted in the urine. Specific disorders of
amino acid intolerance are well described in infants and children with major and
often life-threatening, disorders. These disorders occur when the DNA code is
defective or not read properly into correct enzyme construction. The patterns of
the major inborn errors of metabolism have minor versions in individuals who are
less obviously dysfunctional. The major amino acid disorders are readily
diagnosed by clinical and laboratory examinations; the minor manifestations are
difficult to detect. Disorders of amino acid metabolism demonstrate what happens
when a specific enzyme is deficient or malfunctions. There are two basic
consequences:
- An amino acid, which should be utilized, accumulates or follows another
route of metabolism and produces toxicity.
- The products usually made from the amino acid are unavailable with a
defective enzyme system.
Amino acid intolerance in newborn infants shows up as failure to thrive or as
grave life-threatening illnesses. The intolerance may be singular and specific,
or it may be a more generalized inability to metabolize amino acids. All the
branch-chain amino acids not incorporated into protein structure or functional
molecules are processed through a common system, which is found in the
mitochondria of all cells. We can call this Mitochondrial Amino Acid Processor,
MAAP.
MAAP allows us to burn excess AA's as fuel by breaking down amino acids in a
sequence which requires 3 enzymes and the co-factors, Biotin, Vitamin B12, and
magnesium. If the enzymes are deficient or fail to function properly, amino acid
processing is blocked. The more severe blocks result in a gravely ill infant who
is sleepy or unconscious, projectile vomits, smells odd, and displays prolific
growth of the yeast, candida, appearing in the mouth as "thrush" or on the skin
as red scalded-looking areas, especially in the diaper area. The most afflicted
infants die of dehydration and infection and not all can be saved, even by the
most skilled management. Their urine shows abnormal amounts of amino acids
(aminoaciduria) and ketosis, which results from the increased oxidation of fatty
acids as a fuel.
MAAP may malfunction when the cofactors Biotin and VMB12 are missing. A good
way to check the functional presence of VMB12 is to measure the urine excretion
of Methylmalonic Acid, the second-step product of MAAPs processing, which
accumulates if VMB12 deficiency limits its conversion to the step three product,
Succinyl CoA. Succinyl CoA is the pivotal molecule, linking amino acid
metabolism to carbohydrate metabolism. If your MAAP cannot turn amino acids into
succinyl CoA, then you do not want to eat many of them.
Biotin is supplied in our food, but also by colon bacteria, as a
by-product of their metabolism. Reduced dietary intake, coupled with
interference with colon biotin production by antibiotics, colonics, or surgery
is required before deficiency is manifest. Biotin deficiency will cause MAAP
dysfunction. An interesting relationship is the interference of biotin
absorption by a protein in egg white, Avidin. High intake of raw eggs can induce
biotin deficiency. Some errors of metabolic processing of biotin are known and
may be corrected by administering high daily doses of biotin.
