Why do we age? Why do living creatures have a finite period of existence? What is the nature of the clock of life whose alarm we can’t turn off? As a species, human beings have now survived for 400,000 years, but not as individuals. Still, we can consider ourselves fortunate compared with some life-forms that measure their life spans in mere days . Among animals, the gastrotrich, a minute sea creature, has the briefest life expectancy-about three days-whereas the giant tortoise can live more than 170 years. Plants can live for extraordinary periods, like the Methuselah tree, a bristlecone pine found in California, which is estimated to be 4,725 years old. People fall somewhere in the middle range.
Lest you think this is science fiction, we have already seen an increase in life span of about three months every year since the mid nineteenth century: This is generally attributed to the industrialization of food production, which created a readily available food supply; and to the introduction of childhood immunizations and antibiotics. But some researchers believe that even with the most advanced medical care, the average human life span has very little room to increase further. In fact, there is evidence that in some countries, like Russia, life span can even backslide. The discovery of substances that could extend life is therefore both very intriguing and very controversial, and must be examined in the context of scientific trial and error and, most important, through confirmation by other scientists, the litmus test of scientific progress.
What Is Normal Aging?
“Satchel” Paige, who was still pitching in major league baseball in his fifties, once asked, “How old would you be if you didn’t know how old you were?”
Chronological age-(the number of years you’ve lived )-doesn’t necessarily correlate with physiological age. If we can prevent chronic diseases and disability through diet, exercise, and avoiding environmental hazards such as pollution and pesticides, we can stay much younger than our chronological age. Of course, corning from a family blessed with long life in its genetic history can also help.
Certainly aging does not manifest itself in the same way in every person. Genetic predisposition and lifestyle are major additional influences on aging. To discover just what happens to various organs as people age, the National Institute on Aging supported the Baltimore.
Causes of Aging
Longitudinal Study of Aging, which has tracked more than 1,400 men and women, ranging in age from their twenties to their nineties.
What are the symptoms of aging – Different Organs Are Affected by Aging ?
The heart wall thickens, gradually losing its effectiveness as a pump. Maximum oxygen consumption during exercise declines with each decade of adult life by about 10 percent in men and 7.5 percent in women.
Cholesterol and calcium build up, thickening and stiffening the arteries. The decrease in elasticity and the narrowing of the arteries lead to high blood pressure.
Between the ages of twenty and seventy, maximum breathing capacity declines by approximately 40 percent. A gradual decrease in the number of brain cells leads to selective impairment, particularly in memory.
The bladder gradually loses its tone, and incontinence or loss of control of urine may occur as the tissues weaken, particularly in women.
Body fat gradually increases until middle age. It then usually stabilizes until late life, when body weight tends to decline. Elderly individuals lose not only body fat but also muscle and thus develop sagging skin.
Between the ages of thirty and seventy; muscle mass declines by approximately 22 percent for women and 23 percent for men. (Exercise slows, and even reverses, this rate of loss.) Bone density and minerals are lost, particularly in women at menopause. This loss accelerates and leads to osteoporosis and fractures.
Vision begins to fade in the forties. There is increased susceptibility to glare and greater difficulty in seeing at low illumination. In older people, high-frequency tones are lost so that impairment with background noise becomes substantial. Hearing declines more quickly in men than in women.
All of these abnormalities occur eventually; but they can be greatly delayed and at times prevented by appropriate diet and exercise.
Theories of Aging
Many theories have been proposed to explain why we age and eventually die; however, none has gained supremacy.
“Next to the miracle of life itself, aging and death are perhaps the greatest mysteries.” Nevertheless, theories of aging can be divided into two groups: error theories and programmed theories.
1) Gene Theory of Aging
This theory is derived from Darwin’s evolutionary theory of natural selection. It supposes that we inherit genes that limit our lifespan amongst other species.
2) Theory of Programmed Cell Death
All cells in our body are made up of chromosomes which contain the genetic material, called DNA. This theory suggests that each time a cell divides, these chromosomes become shorter, thereby limiting the number of cell divisions. During infancy and childhood, cell divides rapidly. But as we age, cell division slows down and eventually stops.
3) Aging as a Consequence of Oxidative Stress
When our body is subjected to stress (e.g. illnesses, toxins, chemicals), we produce a lot of free radicals in the body. These free radicals can damage the cells and organs of the body, causing premature cell death.
4) Aging as a Consequence of Hormone Losses
Hormones are chemicals in the body which are vital for bodily functions. Take for instance, estrogen which is a female sex hormone. Aside from its reproductive function, estrogen has also a role in maintaining bone density. Hence during menopause, when estrogen is low in women, the risk for osteoporosis which is common in elderly women is high.
5) Aging as a Result of High Energy Consumption
The energy consumption hypothesis says that burning more calories can increase damage to cells, resulting in more rapid aging. On the other hand, severely restricting calorie intake can prolong life and slow down the progression of age related symptoms. Thus, the slower your body metabolism is, the longer your life will be.
Error Theories of Aging
Perhaps the most notable error theory concerns free radicals. In every cell, there are hundreds of mitochondria, tiny organelles that convert oxygen and glucose into adenosine triphosphate (ATP). ATP is the energy-releasing molecule needed for almost all cellular reactions. In the normal process of “burning” oxygen and carbohydrates, mitochondria form by-products called free radicals, created when the mitochondria combine oxygen with hydrogen to form water and an oxygen molecule escapes with an extra electron.
These oxygen atoms with a free or unpaired electron (free radicals) are unstable and break down into several additional types of free radicals that attempt to “steal” electrons from other molecules. Sometimes this is helpful, as when free radicals destroy bacteria or other invaders. However, in excess, free radicals can damage the membranes of cells, the proteins within cells, and even the DNA itself.
Oxidative damage to proteins, membranes and genes.
This Oxidative damage called as “oxidative stress” has been implicated in the cause of many diseases such as cancer and Alzheimer’s and has an impact on the body’s aging process.
There are other sources of free radicals besides the mitochondria, however, such as sun exposure, radiation, tobacco smoke, and other environmental factors. In fact, radiation therapy to treat cancer depends on free radicals generated by the radiation to kill the cancer cells. Free radicals have been implicated in all aspects of aging, from degenerative disorders to cancer, cataracts, atherosclerosis, and brain degeneration, as we will see.
To neutralize these free radicals that cause damage through oxidation, cells call upon antioxidants. In a healthy body, nutrients like vitamins C and E, along with various enzymes, are powerful antioxidants that normally prevent damage by the free radicals. Antioxidants are now often added to food and drinks, which are then called “functional foods.”
– (A) Oxygen and glucose generate cellular energy (ATP) and in the process form destructive free radicals. (B) Excessive free radicals damage cellular membranes, mitochondria, and DNA.
Marketed as containing nutrients to protect cells from damage due to oxidation, 1,013 products making “high antioxidant” claims were introduced in 2006.
The Mars chocolate company recently put an antioxidant label on its Dove chocolate and saw its business double in a year. In the first three months of 2007, more products with antioxidant claims came out than in all of 2004. The best source of antioxidants, however, isn’t packaged foods, according to nutritionists, but natural (and preferably organically) grown fruits and vegetables.
Another error theory of aging is that of cross-linking. People who have elevated blood sugar, particularly diabetics, are subject to developing what are called advanced glycation end products (AGEs). In this process, glucose molecules attach themselves to proteins or fats. Anyone who has basted a Thanksgiving turkey and watched the skin turn brown and stiff is seeing AGEs in action. The cross-linked glucoseprotein material is responsible for the stiffening and has a similar effect on human skin and on the connective tissue that supports our joints, tendons, and internal organs. The number of AGEs increases with age and accelerates the process of aging and organ failure. This is especially evident in diabetics who develop premature heart, kidney, and/or blood vessel damage, plus cataracts all accelerated by AGEs.
A third error theory is that of repetitive damage to the DNA in the nucleus and the mitochondria of the cell. Each of the trillions of cells in the body strives to maintain a balance between a continual assault by oxygen-free radicals, the sun’s ultraviolet radiation, and other toxic agents, and the normal mechanisms needed to repair the damaged DNA. When the repair system is overwhelmed, genetic mutations in the cell’s DNA accumulate over time. This results in cellular deterioration, malfunction, and even cancer. Damage to the mitochondrial DNA is thought to cause many muscle disorders, as well as inflammatory diseases such as Alzheimer’s.
Error theories include the belief that over time, cells simply begin to function poorly and wear out and that “most aging is just the ‘dry rot’ we program into our cells by sedentary living, junk food, and stress.” Although the body is composed of trillions of cells, most live only a few weeks or months, then die and are replaced in an endless cycle. Although this isn’t entirely true for all organs (such as the brain and heart), our cells do create a “new” body approximately every three months-leaving many opportunities for errors in cell reproduction. Cancer is an example of just such a mistake.
Programmed Theories of Aging
These theories involve loss of organ function at a specific rate as we age. One such theory of aging involves the endocrine glands, which produce hormones such as estrogen, “testosterone, growth and thyroid hormones, DHEA, and melatonin“. All of these hormones gradually decrease with age.
For example, human growth hormone from the pituitary gland normally peaks at around age thirty and then gradually declines thereafter . A study by David Rudman in the New England Journal a/Medicine in 1990 showed that in elderly patients, growth hormone supplements led to improved memory, decreased age related stomach fat, thicker muscles and skin, and an overall feeling of wellness. In a follow-up article in 2003, also in the New England Journal of Medicine, Mary Lee Vance expressed concerns about Rudman’s study because of the lack of evaluation of long-term side effects and also the fact that more recent similar studies had shown no strength improvement. Although still controversial, today human growth hormone supplementation has become an underground cult movement.
Hormones, produced by various glands, are chemicals that control the activities of organs and other parts of the body. For example, the male sex hormone, testosterone, formed in the testicles, has a profound effect on muscle size and strength, as well as sex drive and mood. Testosterone production peaks in early adulthood, then tapers off as we age. The National Institute on Aging is investigating the role of testosterone supplementation in delaying or preventing frailty in the elderly. Similarly, the female sex hormone, estrogen, made in a woman’s ovaries, has a powerful effect on bone growth and development; it also regulates the menstrual cycle. Deficiencies in this hormone may result in osteoporosis and menopausal symptoms. Other hormones such as DHEA and melatonin are also touted as antiaging, and at times even miraculous in their effects on general health. All of these hormones can be measured in the blood. If they are low, replacement can indeed be life transforming.
A decline in immunity also falls under programmed aging. The immune system, composed of the tonsils and adenoids, thymus gland, lymph nodes, spleen, lymphatic vessels, and cells in the bone marrow, produces powerful blood cells and substances that neutralize or kill invaders such as bacteria, viruses, and other foreign bodies. When our immune system is strong, we have few colds or infections and our energy level is high. When we are exposed to the high bacterial count in a crowded airplane, for example, we become sick to varying degrees, depending on the strength of our immune system. With age, the organs in the immune system gradually fail, so that we become much more susceptible. Fortunately, there are ways to enhance the immune system to better fight infections, such as including natural xeno factors in our foods.
Mental stress and depression have long been known to weaken the immune system. In ancient Rome, Galen, the physician to the gladiators, observed that bereavement and depression from the death of a spouse could itself lead to an early death. Beginning in the 1980s, a new field called psychoneuroimmunology emerged to decipher the biochemical connections between the mind and body The biblical statement ‘as a man thinketh, so he shall be” may well be accurate. It turns out that when we are depressed, our thoughts and feelings suppress cells in our immune system, increasing our susceptibility to sickness. When we use positive thinking, meditation, and prayer and have a strong family support system, we are much more effective at warding off disease.
The final programmed theory of aging relates to telomeresrepetitive DNA sequences at the end of chromosomes. Like the plastic covering on the ends of shoelaces, these telomeres help to keep the chromosome intact. Each time cells divide, our telomeres get shorter. It is thought that over time the telomeres become so short that their function is disrupted, leading to cells that no longer divide and proliferate. By measuring the length of telomeres, we can get some idea of how many cell divisions have already occurred and how many remain before a particular cell can no longer replicate.
This biological clock keeps track of the cell’s age and serves as a molecular marker to measure cellular division. As the telomeres fray, cells wear out, and the organism dies. This raises two important questions: How do the cells that make up the next generation- the male sperm and the female egg-avoid this fate, and how do cancer cells continue to grow?
Dr. Jerry Shay and Woody Wright, professors in the department of cell biology at the University of Texas Southwestern Medical Center, have provided the answer. They discovered that an enzyme called telomerase enables cells to replace the lost telomeres and then to divide indefinitely In the case of the reproductive cells and stem cells (the master cells, with the ability to grow into anyone of the body’s more than two hundred cell types), this is a necessary and important process, but when the telomerase gene is activated erroneously in other cells, it can allow tumors to grow unchecked. Cancer research has been focusing on drugs to block telomerase, and the precise role of telomere shortening in aging and cancer is one of several research avenues that scientists continue to pursue vigorously.
In reviewing these various theories of aging, it becomes immediately apparent that aging has multiple causes. In mammals, aging is dependent in large part on the type of maintenance mechanisms evoked to slow this decay and deterioration of our cells and organs. We are referring to the repair of DNA, defense systems against oxygen free radicals, enhancement of the immune response, removal of defective proteins and mutated cells, and the detoxification of harmful chemicals in our diet.
These maintenance mechanisms bring us directly back to the xeno factor, for researchers are finding that the plant chemicals found in xeno factors perform all of these functions. By activating specific mechanisms within our cells, they help to control inflammation, regulate cell survival, repair cells, and prevent cell death. As antioxidants, they work to enhance the all-important performance of the immune and endocrine systems.
Signs that the Skin is Aging
* fine wrinkles
* thin skin that is more fragile and susceptible to damage (cuts, tears, bruises) and takes longer to heal
* transparent (see-through) skin
* dull and lifeless appearance to the skin and it becomes less plump
* greater visibility of skin pores
* hollowed cheeks and eye sockets
* loss of skin firmness on the hands and neck
* sagging skin in the face, neck, and upper arms and loss of the skin’s elastic nature
* dry, flaky and itchy skin (eczema)
* spider veins – veins that are fine and red, purple, or blue in colour that have the appearance of spider legs all clustered in one area and usually appear on the feet, ankles, and thighs
* varicose veins – enlarged leg veins that are bulging and blue in colour
* varicose ulcers – infection in the area of a varicose vein often around the ankles; affected areas are usually swollen, red, itchy and may contain pus
* purpura – rupture of blood vessels leading to the presence of flat purplish patches under the skin
* cherry angiomas – small bright red raised bumps cause by dilated blood vessels and usually found on the trunk of the body
* reduction in the amount of sweating (cooling of the skin is affected)
* reduction in the amount of oil or lipid production and therefore more dry skin care problems
* hair loss or unwanted hair on certain skin areas
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