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The Hayflick Limit Theory
Pictured: Dr. Leonard Hayflick
The Hayflick Limit Theory of Aging (so called after its discoverer Dr. Leonard Hayflick) suggests that the human cell is limited in the number of times it can divide. Part of this theory may be affected by cell waste accumulation (which is described in the Membrane Theory of Aging).
Working with Dr. Moorehead in 1961, Dr. Hayflick theorized that the human cells ability to divide is limited to approximately 50-times, after which they simply stop dividing (and hence die).
He showed that nutrition has an effect on cells, with overfed cells dividing much faster than underfed cells. As cells divide to help repair and regenerate themselves we may consider that the DNA & Genetic Theory of Aging may play a role here. Maybe each time a cell divides it loses some blue-print information. Eventually (after 50-odd times of division) there is simply not enough DNA information available to complete any sort of division?
We also know that calorie restriction in animals significantly increases their life-span. In essence less fed animals live longer. Is this because they are subject to less free radical activity (see the Free Radical Theory of Aging) and therefore less cellular damage? Or is it that insulin and glucose damage (see the Cross-Linking Theory of Aging and the Neuroendocrine Theory of Aging for details) is less prevalent in them than in overfed animals?
The Hayflick Limit indicates the need to slow down the rate of cell division if we want to live long lives. Cell division can be slowed down by diet and lifestyle etc., but it is also surmised that cell-division can be improved with many of the protocols of the other aging theories described herein.
The use of ribonucleic acids (RNAs, the building-blocks of DNA), improve cell repair processes, enhance cellular capabilities and increase the maximum number of cell divisions in animals and vitro tests. Human clinical studies with RNA supplements such as NeyGeront ® and RN13 ® indicate that there are a number of biological, physiological and practical improvements for geriatric patients.
If laboratory results prove true also for the individual, then Carnosine will be another potent Hayflick Limit extender.
The Mitochondrial Decline Theory
The mitochondria are the power producing organelles found in every cell of every organ. Their primary job is to create Adenosine Triphosphate (ATP) and they do so in the various energy cycles that involve nutrients such as Acetyl-L-Carnitine, CoQ10 (Idebenone), NADH and some B vitamins etc.
ATP is literally the life giving chemical because every movement, thought and action we make is generated from it. Yet very little ATP can be stored in the body.
It is estimated that a 180 lb. man needs to generate an average of 80-90 lbs. of ATP daily! Under strenuous exercise the use of ATP may rise to as much as 1.1 lbs. per minute! But reserves of ATP are considered to be no more than 3-5 ounces, thus under those same strenuous exercise conditions that's approximately 8-seconds worth! Thus it becomes apparent that the mitochondria have to be very efficient and healthy, in order to produce a continuous supply of essential ATP for the necessary repair and regenerative process to occur.
Chemically speaking, under normal conditions the mitochondria are fiery furnaces and subject themselves to a lot of free radical damage (see the Free Radical Theory of Aging). They also lack most of the defenses found in other parts of the body, so as we age the mitochondria become less efficient, fewer in number and larger. Accordingly, ATP production declines.
As organs cannot borrow energy from one another, the efficiency of each organs mitochondria are essential to that particular organs repair processes and functions. If a particular organs mitochondria fail, then so does that organ (which of course can lead to death).
Enhancement and protection of the mitochondria is an essential part of preventing and slowing aging. Enhancement can be achieved with the above mention nutrients, as well as ATP supplements themselves. Protection may be afforded by a broad spectrum of anti-oxidants substances, as well as substances such as Idebenone and Pregnenolone.
Of particular use may be Acetyl-L-Carnitine and Hydergine, both of which have been proven in experiments to greatly improve the mitochondria condition of aged animals.
The Cross-Linking Theory
The Cross-Linking Theory of Aging is also referred to as the Glycosylation Theory of Aging. In this theory it is the binding of glucose (simple sugars) to protein, (a process that occurs under the presence of oxygen) that causes various problems.
Once this binding has occurred the protein becomes impaired and is unable to perform as efficiently. Living a longer life is going to lead to the increased possibility of oxygen meeting glucose and protein and known cross-linking disorders include senile cataract and the appearance of tough, leathery and yellow skin.
Indeed, you can see cross-linking in action now. Simply cut an apple in half and watch the oxygen in the air react with the glucose in the apple as it turns yellow and brown and eventually becomes tough.
Diabetes is often viewed as a form of accelerated aging and the age related imbalance of insulin and glucose tolerance leads to numerous problems; these have been called Syndrome X. In fact, diabetics have 2-3 times the numbers of cross-linked proteins when compared to their healthy counterparts.
The cross-linking of proteins may also be responsible for cardiac enlargement and the hardening of collagen, which may then lead to the increased susceptibility of a cardiac arrest.
Cross linked proteins have also been implicated in renal disorders.
It is also theorized that sugars binding to DNA may cause damage that leads to malformed cells and thus cancer.
The modern diet is of course a very sweet one and we are bombarded with simple sugars from soft drinks and processed foods etc. One obvious example to reduce the risk of cross-linking is to reduce sugar (and also simple carbohydrates) in ones diet. Some pharmacological interventions that could help reduce the carbohydrate/ starch/ glucose intake and affect, include Acarbose and Metformin.
But other supplements are also appearing that show great promise in the battle to prevent, slow and even break existing cross-links. Two of the most important at present are Aminoguanidine and the amino-acid Carnosine.
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