Topics to be covered
Definition
Starting at what is commonly called middle age, operations of the human body begin to be more vulnerable to daily wear and tear; there is a general decline in physical, and possibly mental, functioning. In the Western countries, the length of life is often into the 70s. The upward limit of the life span, however, can be as high as 120 years. During the latter half of life, an individual is more prone to have problems with the various functions of the body and to develop any number of chronic or fatal diseases. The cardiovascular, digestive, excretory, nervous, reproductive and urinary systems are particularly affected. The most common diseases of aging include Alzheimer's, arthritis, cancer, diabetes, depression, and heart disease.
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Description
Human beings reach a peak of growth and development around the time of their mid 20s. Aging is the normal transition time after that flurry of activity. Although there are quite a few age-related changes that tax the body, disability is not necessarily a part of aging. Health and lifestyle factors together with the genetic makeup of the individual, and determines the response to these changes. Body functions that are most often affected by age include:
- Hearing, which declines especially in relation to the highest pitched tones.
- The proportion of fat to muscle, which may increase by as much as 30%. Typically, the total padding of body fat directly under the skin thins out and accumulates around the stomach. The ability to excrete fats is impaired, and therefore the storage of fats increases, including cholesterol and fat-soluble nutrients.
- The amount of water in the body decreases, which therefore decreases the absorption of water-soluble nutrients. Also, there is less saliva and other lubricating fluids.
- The liver and the kidneys cannot function as efficiently, thus affecting the elimination of wastes.
- A decrease in the ease of digestion, with a decrease in stomach acid production.
- A loss of muscle strength and coordination, with an accompanying loss of mobility, agility, and flexibility.
- A decline in sexual hormones and sexual functioning.
- A decrease in the sensations of taste and smell.
- Changes in the cardiovascular and respiratory systems, leading to decreased oxygen and nutrients throughout the body.
- Decreased functioning of the nervous system so that nerve impulses are not transmitted as efficiently, reflexes are not as sharp, and memory and learning are diminished.
- A decrease in bone strength and density.
- Hormone levels, which gradually decline. The thyroid and sexual hormones are particularly affected.
- Declining visual abilities. Age-related changes may lead to diseases such as macular degeneration.
- A compromised ability to produce vitamin D from sunlight.
- A reduction in protein formation leading to shrinkage in muscle mass and decreased bone formation, possibly leading to osteoporosis.
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Theories on the Causes of Aging
Theoretical Disclamer
While thinking about these theories, one must remember the differences between cause and effect. Some are based on observations of aging cells. While the following theories may be valid causes of aging, they may also simply note an effect of the aging process. For example, gray hair is found primarily in the elderly, but does not play an active part in the aging process. Also keep in mind that individually, these explanations do not account for the complex process of biological aging. Thus, aging may be most accurately described by the synthesis of several of the following theories.
Current theories can, in general, be separated into two groups:
DNA Damage Theories
Aging is caused by accumulated damage to DNA, which in turn inhibits cells' ability to function and express the appropriate genes. This leads to cell death and overall aging of the organism.
- DNA Damage/Repair Theory
- Free Radical/Oxidation Theory
- Mitochondrial DNA Theory
- Radiation Theory
Built-In Breakdown Theories
Aging is a direct consequence of genetic programming. The causes for aging are directly built into the genome and cellular structure, as a sort of molecular clock.
- Disposable Soma Theory
- Genetic Theory
- Immunological Theory
- Telomere Theory
DNA Damage/Repair Theory
DNA damages occur continuously in cells of living organisms. While most of these damages are repaired, some accumulate, as the DNA Polymerases and other repair mechanisms cannot correct defects as fast as they are apparently produced. In particular, there is evidence for DNA damage accumulation in non-dividing cells of mammals. These accumulated DNA damages probably interfere with RNA transcription. It has been suggested that the decline in the ability of DNA to serve as a template for gene expression is the primary cause of aging. Most damage comes in the form of oxidative damage, and hence is likely to be a prominent cause of aging.
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Free Radicals & Anti-Oxidants
Free Radicals
In general, a free radical is any molecule with one or more unpaired electrons in its valence shell. In the discussion of aging, the free radicals of importance are oxygen-based molecules such as superoxide (O2-), hydroxy radical (OH), singlet oxygen (O), hydrogen peroxide (H2O2), and hypochlorous acid (HOCl). Free radicals, though attractive and charming, are damaging to the body because they are extremely reactive; they tend to rip electrons off of other molecules in order to pair off their lone electrons. In other words, free radicals are strong oxidizing agents.
Unfortunately, free radicals cannot be avoided since they are byproducts of essential reactions in the body, such as the process of metabolizing oxygen. Free radicals can also be found in abundance in the environment: air pollution, tobacco smoke, radiation, toxic waste, and certain chemicals.
Free radicals wreak havoc at a cellular level since they are able to:
- break off cell membrane proteins, thereby destroying cellular identity.
- fuse membrane lipid & proteins, hardening the cell membrane and leading to brittle and nonfunctional cells.
- disrupt the nuclear membrane. Free radicals may expose genetic material in the nucleus, leaving the DNA open for mutation or destruction.
- burden the immune system by damaging immune cells.
- cause chronic diseases.
These effects are known as oxidative stress, and may lead to DNA mutations, cell death, and disease, all of which contribute to the overall effects of aging. To prevent oxidative stress, one should reduce environmental burdens in the body (chemicals/heavy metals), reduce stress, improve the quality of one's food supply, and (if possible) increase one's antioxidant mechanisms.
Antioxidants
Antioxidants are the body's solution to oxidative stress. These molecules neutralize free radicals by supplying them with extra electrons. This exchange results in lowering the reactivity of the free radical and leaving the antioxidant itself with an unpaired electron. The structure of an antioxidant, however, is not damaging to the body since it is stabilized through chain reactions with other antioxidants.
Known antioxidants include:
- enzymes such as glutathione peroxidase, catalase, superoxide dismutase.
- nutrients including vitamins C and E, beta carotene, selenium, cystene, uric acid.
- synthetic molecules such as DSMO, BHT, and BHA.
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The Free Radical / Oxidation Theory
This, perhaps one of the most respected and well-studied theories, rests on the fact that oxidants induce a variety of distinct biochemical changes in target cells. Hydrogen peroxide is considered one of the more troublesome oxidants, as it diffuses into target cells where site-directed hydroxyl radical formation injures specific targets. DNA is particularly sensitive to hydroxyl radical-induced damage: both DNA strand breakage and base hydroxylations can be detected. The breakage of the DNA strand activates a DNA binding protein (poly(ADP-ribose)polymerase), which forms polymers of ADP-ribose bound to various nuclear proteins using NAD as its substrate. NAD turnover under these circumstances increases so dramatically that it affects ATP synthesis, to the point where high enough concentrations inactivates mitochondrial ATP synthesis.
If the concentration of hydrogen peroxide is high enough, these pathways will lead to cell death, and, therefore, hydrogen peroxide-induced alterations will not be passed on to future generations. If, however, cells are exposed to sub-lethal concentrations of hydrogen peroxide, the ensuing injury could cause permanent and transmissible cellular alterations which could be biologically detrimental. For instance, if hydroxyl anion-induced DNA damage fails to be repaired or is improperly repaired, this DNA damage could lead to genetic alterations such as mutations, deletions, and rearrangements. Moreover, if these genetic alterations occur in critical genes that are involved in cell growth and differentiation, they could lead to deregulated cell growth and differentiation and ultimately contribute to the malignant transformation of cells. Hence, the growing number of free radical diseases includes the two major causes of death, cancer and arteriosclerosis.
Since hydrogen peroxide easily defuses through cell membranes, hydroxyl anion formation may occur extra- or intracellularly, depending on the availability of transition metals. Because of its high reactivity, the hydroxyl radical will always cause site- directed damage at the site of its formation. However, the body does possess some natural antioxidants in the form of enzymes which help to curb the dangerous build-up of these free radicals, without which cellular death rates would be greatly increased, and subsequent life expectancies would decrease.
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Mitochondrial DNA Theory
This theory suggests that the loss of effectiveness of one of the cell's key organelles paves the way for age-related degenerative diseases. The mitochondria, which are the energy-producing bodies within a cell, have their own genome (mtDNA). This mtDNA is synthesized at the inner mitochondrial membrane near the sites of formation of highly reactive oxygen species. Mitochondrial DNA seems unable to counteract the damage inflicted by these by-products of respiration because, unlike the nuclear genome, it lacks advanced repair mechanisms. Thus, the cell loses its ability to produce energy, and gradually dies. This theory is supported by observations confirming the genomic instability of mitochondria, as well as widespread mtDNA deletions and other types of injury to the mitochondrial genome.
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Radiation Theory
This theory is focused primarily on the aging of skin cells, as they are most directly affected by external sources of radiation. Radiation can create free radicals in cells, as the radiation strikes surrounding water molecules and other proximal targets. Thus the aging process goes back to the free radical theory on aging mentioned above, with radiation serving to increase its rate. Experimental studies have recently shown that the shorter, more energetic spectrum of the ultraviolet range (UVB) is responsible for the dermal connective tissue destruction observed in photoaged skin. Also, it has been shown that UVA and infrared radiation contribute significantly to photoaging, producing, among other changes, severe elastosis. Thus, even small amounts of radiation is enough to accelerate the aging process, although this theory is, as they say, only skin-deep.
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Disposable Soma Theory
Soma, or somatic cells, are all the cells in the body except gametes and cells involved in gamete formation. This theory suggests that because of the requirement for reproduction, natural selection favors a strategy that invests fewer resources in maintenance of somatic cells than are necessary for indefinite survival. Therefore, energy will be spent to ensure minimum damage to molecular structures such as DNA, and to ensure that the animal remains in sound condition through its natural life expectancy in the wild, where accidents are the predominant cause of death. Since longevity is costly energy- wise, and since with age there is no longer any ability to reproduce and hence pass genetic material onto subsequent generations, there is simply no reason to keep an organism alive past its time of procreation.
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Genetic Theory
Experiments have shown that human cells will divide less than 100 times outside the body. Also, there is an inverse correlation between the number of cell divisions and the age of the person from which the cells were taken. This theory suggests that cell senescence is an active process, as even though they are unable to divide, senescent cells are actively metabolizing. It has been suggested that senescence is genetically programmed, and that its phenotype is dominant, illustrated by the fact that when normal and immortal human cells were fused, they showed limited division potential. Senescent cells express highly abundant DNA synthesis inhibitory mRNA's and produce a surface membrane associated protein inhibitor of DNA synthesis not expressed in young cells. Thus, this theory suggests that aging is predetermined in the genome, and that it is a dominant condition, although the onset of the phenomenon is still unknown.
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Immunological Theory
It is well documented that the effectiveness of the immune system peaks at puberty and gradually declines thereafter with advance in age. This seems to be based primarily on T-cells, and it is generally associated with an increase in susceptibility to infections as well as in incidence of autoimmune phenomena in the elderly. T-cells lose effectiveness in early life due to the decay of the thymus gland. In other words, the quality and quantity of T-cells begins to decline after puberty. Therefore, as one grows older, certain antibodies lose their effectiveness, and fewer new diseases can be combated effectively by the body, which causes cellular stress and eventual death.
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Telomere Theory
This theory suggests that cell death is caused by the shortening of telomeres, which are "caps" on the ends of chromosomes. It has been observed that with each cell division the telomeres are shortened by approximately 65 base-pairs. Telomeres function by permitting complete replication of eukaryotic chromosomes, and by protecting chromosome ends from recombination. It has been shown experimentally that cell strains with shorter telomeres undergo significantly fewer doublings than those with longer telomeres. These observations suggest that telomere length is a biomarker of somatic cell aging in humans and is consistent with a causal role for telomere loss in this process. When the telomeres get too short, the cell stops replicating at an appreciable rate, and so it dies off, which eventually leads to the death of the entire organism.
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Is the Aging Process Variable?
Diseases Involving Accelerated Aging
Several diseases have the effect of rapidly increasing the rate at which the carrier ages. For example, patients afflicted by progeria suffer from arteriosclerosis, coronary artery disease, congestive heart failure and non-healing fractures by the age of seven. Degeneration of hair follicles leads to balding. Most progeria sufferers die by the age of 30. Several other diseases are known to have similar effects, including Cockayne syndrome and Werner's syndrome.
Possibilities of Increased Lifespan
As things stand, the maximum human lifespan is about 120 years. As a whole, human knowledge is increasing at an exponential rate. By this logic, some scientists believe the human lifespan could be increased to between 400 and 1,000 years within the next 20 years. (Of course, we wouldn't really know for 400 more years...)
The following are some theories on increasing the human lifespan:
By increasing the amount of antioxidants in one's system, one will have less damaging free radicals in the body. The necessary antioxidants can be found in several sources:
- Multivitamin pills, especially Vitamins C and E.
- Beta cerotene
- Zinc
- Selenium
- Calcium
- Magnesium
- Chromium Picolinate
- Coenzyme Q-10
Telomerase has been discovered in some germs and cancer cells, but not in most normal organisms. This enzyme replaces/repairs shortened telomeres such that the cells are able to replicate (theoretically) forever. If the telomerase gene could be activated or spliced into regular human cells (assuming telomere theory is correct), human longevity would be greatly increased.
A mutant form of the gene age-1 in the worm C. elegans caused the worm's lifespan to double. The gene apparently codes for an enzyme important in the mediation of cellular communication and signal transmission. Increased lifespan was observed when the age-1 gene was nonfunctional.
Injection of growth hormone into men seemed to reverse some signs of aging. Experiments with other hormones, such as estrogen and testosterone, are ongoing.
How to Slow Down Aging Process
There are three types of aging – chronological age (which is your age according to your date of birth), biological age (which is measured by looking at certain bio markers), and psychological age (which is dependent on your attitude.)
It is now known that psychological age correlates more closely to biological age than chronological age. If you have the attitude that you get better as you grow older in every way – physically, emotionally, spiritually and socially, then you will age in a much more graceful manner.
The well known biological markers of aging include: blood pressure, bone density, body temperature regulation, basal metabolic rate, immune function, sugar tolerance, muscle mass, muscle strength, skin hickness (amount of wrinkles) immune function, and sex hormone levels.
If you want to slow down or even reverse these bio markers of aging, then practice one or more of the following:
1. Change your perception of time. Don't be in a hurry.
2. Get restful sleep.
3. Eat fresh, nutritious food.
4. Take at least two multivitamins with minerals every day.
5. Practice a mind body technique such as yoga or tai chi.
6. Exercise regularly.
7. Don't put toxins in your life, including toxic food, toxic
emotions, toxic relationships, and avoid toxic environments or toxic relationships.
8. Have a flexible attitude to minor hassles.
9. Look at so-called problems as opportunities.
10. Nurture loving relationships.
11. Always have an attitude of curiosity, learning, and wonder and spend time with children.
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Tips for Remaining Young
- Avoid processed foods and eat only freshly prepared meals. Most processed foods contain harmful fats (omega-6 fats), additives and even toxic metals. In addition, they contain too much salt and sugar.
- Eat five to 10 servings of fresh vegetables and some fruits every day. Choose nutrient-dense vegetables like broccoli, cauliflower, Brussels sprouts, kale, celery, parsley, tomatoes, mustard greens, turnip greens, collard greens, squash and onions. Because fruits are high in sugar, eat only limited amounts and avoid sweetened fruit juices. These foods contain vitamins, minerals and special substances called flavonoids that are powerful and versatile antioxidants. In addition, some of them often provide other brain-protective nutrients.
- Avoid Omega-6 oils (found in corn, safflower, sunflower, peanut, soybean and canola oils). You should not cook with these oils, nor should you use products that contain them (chips, breads, pastries, etc.).
- Consume at least two ounces of extra-virgin olive oil a day. This oil contains a number of powerful antioxidants, as well as healthy monounsaturated oil. You can use it on a salad or mix it with other foods.
- Take Omega-3 oil supplements and foods enhanced with this healthy fat. This includes Christopher eggs and other egg brands that contain Omega-3. These supplements should not be in gelatin capsules. Get the liquid form of highly purified fish oil. It is molecularly distilled to remove dangerous mercury, polychlorinated biphenyls (PCBs) and dioxins. Keep the oil refrigerated. And be sure to get oil that is high in DHA. The dose is 1,000 mg. of DHA each day. The Omega-3 oils reduce brain inflammation and cool down excessive immune activity.
- Avoid sugar. Sucrose, the sugar used in foods and as a sweetener, causes a greater insulin surge than glucose, the natural form. Extensive evidence has shown that sugar plays a major role in accelerating aging — especially brain aging. This is because sugar revs up the metabolism, which generates a storm of free radicals. In addition, sugar forms abnormal bonds with proteins and this dramatically accelerates aging. High sugar intake compounds the risk of Alzheimer’s disease over 300%. High fructose corn syrup is especially damaging.
- Eat complex carbohydrates that are low on the glycemic index. These include broccoli, cabbage, lettuce, onions and more. You can find the index on the Internet. These foods are absorbed slowly and help avoid an insulin surge (which can lead to hypoglycemia). It is also important to eat only limited amounts of carbohydrates each day. That means no more than two servings (a serving is a cup) with each meal.
- Drink a combination of white tea mixed with rosemary tea. These teas contain powerful antioxidants and have been shown to especially protect the brain against abnormal aging. Two cups a day should be adequate. White tea is the same as green tea but contains much lower levels of fluoride with higher levels of antioxidants.
- If you have amalgam (silver) fillings, find a dentist specially trained in their safe removal and have them taken out and replaced with ceramics. Contact the IAOMT organization (www.iaomt.com) for a list of trained dentists near you. The mercury from amalgams has been shown to vaporize in the mouth, at which point it is absorbed into the blood. In addition, the mercury can travel directly to your brain by way of the olfactory nerves in your nose.
- Avoid continuous stress. Unrelieved stress greatly increases free-radical production and lipid peroxidation in the brain, causing it to age abnormally and rapidly. Make sure you get at least eight hours of sleep a night. Regular moderate exercise is also an excellent way to relieve stress. It has been shown to slow brain aging. However, extreme exercise can have the opposite effect. The Omega-3 oils have also been shown to protect the brain against stress damage.
- Avoid depression. If you become depressed, seek treatment early. A number of studies have shown that depression causes a loss of memory and learning difficulties, and that over time the hippocampus of the brain (the memory and learning center) actually shrinks. Depression is best treated with regular exercise. Avoiding Omega-6 fats and increasing Omega-3s also helps. Omega-3 fats have been shown to improve depression and protect the brain from depression-related damage.
- Once a week, you should fast at least until dinner. Fasting once a week has been shown to dramatically slow brain aging and accelerate repair of this essential organ. Experiments have demonstrated that fasting causes the brain to generate growth-stimulating chemicals (brain growth factor and epithelial growth factor) that promote healing of damaged neurons.
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