Your Glands and You

Visiting the Hormone Kingdom: Your Glands and You

How many of you have one-sided and somewhat negative preconceived notion about "hormones." Aren't they something that makes teenagers wild and sexually crazed, that makes women with PMS miserable and cranky, that has some connection with getting fat, feeling depressed, and developing acne? Won't hormones cause cancer?

Well, there's a little bit of truth in all of those fears. Anything as potent as hormones has the potential to be harmful, if taken in excess and not used properly. Hormones must be harmonized; they must be kept in perfect balance, just like the instruments in a symphony orchestra. As we age, that balance is interrupted by a disproportionate decline in some of the more essential hormones, creating an imbalance and discord in our bodies. The resulting symptoms are often considered to be inevitable accompaniments of aging.

Our goal is to restore a harmonizing balance in a very natural and healthy way. If hormones are not balanced, and if some are given in excess relative to others, adverse side effects will occur. Anything that has a major role to play in the body can have a negative role to play as well if misused.

Hormones can be very potent, and even tiny amounts can have major effects. Adrenaline, for example, is secreted in such minute amounts that the concentration necessary to produce a fight-or-flight reaction is equivalent to one drop in a railroad tank car.

Endocrine glands secrete hormones directly into your bloodstream. From there, they get carried to other organs and to tissues throughout your body. All the pro-longevity hormones discussed in this book are endocrine hormones, secreted directly into the blood. So we'd better inspect the glands from which they originate.

Suppose you're walking down Main Street when a tiger steps out from between two parked cars, opens its large, toothy mouth and, fixing that special look on you that tigers always reserve for tasty morsels, roars hungrily. Your heart begins to pound very fast, you start to move away, and as soon as you're within sprinting distance of a solid door, you cover the ground in record time, open the door, and slam it shut just an instant before six hundred pounds of big cat arrives on the other side, late for lunch. You notice that you're shaking badly. That was an adrenaline surge! Adrenaline, which originates in the central core of the adrenal glands, is the fight-or-flight hormone released into the bloodstream in response to stress and threat.

Or, more realistically, let's say it's May, the time when young people's hearts turn to romance, and you're a young man. You're walking down Main Street when suddenly you see that special young lady walking toward you, as ravishing as ever, charmingly costumed, and smiling your way. Your heart begins to beat harder, your whole body begins to tingle, and the combination of sensations, emotions, and anticipations you're experiencing is fairly indescribable. The suggestion that romance is nothing more than hormones is one I'd never dream of making, but I'm sure there's testosterone involved in this equation somewhere. Testosterone is the male sex hormone produced primarily in the testicles but also, to a lesser extent, in the adrenals.

We're talking endocrinology, and when I tell you that this extraordinary team of hormones secreted by the endocrine glands not only powers your flight-or-fight mechanism and underlies your sex drive but also permits you to grow, allows you to fight infection and heal injury, controls your inner heating apparatus, permits and encourages a good night's sleep, balances the levels of minerals in your body, and adjusts the burning of fuel for energy—then I think you'll understand that deploying the proper quantities of these natural substances daily is every bit as crucial to your continued existence as breathing air.

Moreover, it's now known that the endocrine glands are crucially involved in the timing mechanism of your aging clock. We don't just wear out as we get older, we are phased out. There is a precise, hidden pattern of messages communicating from our glands to the rest of our bodies that corresponds to how far we've come and how far we still have to go. Naturally, accident or illness—perhaps self-inflicted due to our lifestyles—can terminate our time on this planet long before our biological clocks would otherwise have run down. But even if we live with wonderful prudence, the clock is ticking.

Can it be slowed? Can the hands of the clock be turned back? We're not certain, but our present knowledge indicates that the hormonal approach offers us the best chance yet for performing such delicate clockwork alterations. Scientists have succeeded in giving mice life spans that are 30 percent greater than the normal maximum for that species. In my view, that's adjusting the biological clock.

One of the most effective methods used has been endocrine supplementation. Hormone secretion decreases at a predictable rate with age in humans as well as mice. By merely restoring levels to those present in healthy young adulthood, many of the adverse accompaniments of old age can, at least partially, be reversed and forestalled in the future.

Before we consider this novel method for extending your life span and for improving the quality of your more mature years, let's look at the endocrine system gland by gland.

FROM THE BOTTOM UP

We'll start our tour with the gonads—the woman's ovaries and the man's testes. These are the endocrine system's chief production plants for the sex hormones.

We're all familiar with the physical results of the sex hormones—the curves, the breast development, the softer skin of women; the larger muscles, the deeper voice, the relative hairiness of men. Certainly the functional differences in anatomy and the specialization of reproductive function are sufficiently obvious, too. Though many hormones combine in the production of these delightful variations, the two dominant stimulators are testosterone in men and estrogen in women.

That's not the end of the effective action undertaken by these potent anabolic steroids—which is, of course, what the sex hormones are. Anabolic means that they stimulate growth and healing of tissues. These hormones support protein synthesis, bone structure, skin tone, muscle strength, the health and functioning of neural networks in the brain, and many other aspects of strength and vitality. It is not surprising that the sex hormones have such powerful effects. Youthfulness is strongly associated with physical vigor as well as sexual vitality. Nothing more vividly indicates that we're still young, still participants in the game of life, than our sexual urges.

It's only logical to ask whether, by reversing an age-related decline in the sex hormones, we can reverse other aspects of aging as well. And, certainly, the answer appears to be a qualified yes. The last twenty years have fully demonstrated the powerfully vitalizing effects of estrogen supplementation on postmenopausal women; there are some indications that the next twenty will show somewhat similar effects in males who use testosterone supplementally. In the case of men, however, a fundamental difference is that the degree to which male testosterone levels decline with age slower and is far less predictable.

Moving slightly upward in the body we reach the uterus in women and the prostate gland in men. They are, of course, closely related to the sex organs, part of the whole apparatus of reproduction. During pregnancy the uterus manufactures massive quantities of progesterone in order to promote normal functioning of the placenta, the link between the blood supply of the mother and the baby. The ovaries also produce progesterone during the second part of the monthly menstrual cycle.

The prostate gland—source of so much male discomfort in the second half of life—produces various constituents of seminal fluid and also contains a tiny vestigial uterus that never develops further in men. Unfortunately, in the anti-aging scheme of things, the prostate's function is often a negative one; it's the prime male site for cancer. And it often tends to enlarge with age, causing obstruction to the flow of urine from the bladder.

The Tour Continues

The next endocrine gland that we reach in our journey toward the brain is the pancreas, the source of your body's insulin. In healthy people, the pancreas will function efficiently until the end of life, but in people with diabetes there is (depending on the type of diabetes) either a shortage of insulin or a resistance in the body to insulin's effects. Insulin does not really have a place as a pro-longevity hormone. Without it you would simply die. Fortunately, since 1922 it has been possible to provide it by injection to successfully treat diabetes.

Insulin is released whenever we eat carbohydrates such as starches or sugar. It functions to facilitate the transport of blood sugar (glucose) into our cells for fuel. Glucose is stored in the liver and muscles as a complex carbohydrate called glycogen. If insulin is not doing its job properly, then the excess glucose is more easily converted to fat and the breakdown of fat for energy is also impaired. On the other hand, if insulin takes too much glucose out of the blood stream (hypoglycemia), we feel weak and tired and counterregulatory hormones (largely created by the adrenal glands) are released to convert glycogen and/or fat back into glucose, the body's main source of energy.

It's quite typical for the body to use insulin less efficiently as we get older. More insulin is produced to compensate and the resulting increase in blood levels of insulin are now known to accelerate the diseases of aging. Careful diet and exercise can minimize that problem.

Twin Powerhouses

Traveling upward we pass the kidneys and find, at the top of each of them, two little but spectacularly potent glands called the adrenals. In their center (the medullas), the adrenal glands produce adrenaline, the hormone that so spectacularly jump-starts our emergency action system. Adrenaline ignites a high speed burn-off of the starch called glycogen that insulin stores in our muscles and livers. This causes an almost instantaneous rise in blood levels of glucose, fueling the flood of energy that we need for action. Adrenaline also speeds the heartbeat and the breathing rate.

On the outer layer or cortex of the adrenals, one of the body's major hormones, DHEA (dehydroepiandrosterone), is manufactured from cholesterol and DHEA the body makes a wide spectrum of other steroid hormones, including aldosterone, which preserves minerals in the body, and cortisone, which controls immune responses and also affects energy and mineral metabolism.

DHEA is also one of the raw materials from which the reproductive organs make sex hormones, and thus it is now justifiably regarded as one of the most important hormones in the human body. It is significant, therefore, that DHEA declines steadily and predictably with age. When you're in your twenties, your cup is filled to overflowing with DHEA. After that, the long slide starts.

DHEA is sensitive to the immediate conditions of your physical and mental life. Illness depletes it, as does severe stress of any kind.

A Gland That Shrivels

The next hormone-producing center is in the chest behind the heart and is called the thymus gland. The thymus is one of the major organs of the immune system—indeed, in childhood, it's absolutely essential to developing an immune system in the first place. Its principal task is the creation of T lymphocytes, the specialized cells (killer cells) that find helper cell lymphocytes and eliminate bacteria, viruses, and foreign matter from the body. In late childhood the thymus is the size of a plum, but at puberty it begins to shrink. By the time we reach old age, it's the size of a small raisin and relatively inactive. It's interesting that, statistically, a human being is least likely to die at the age of twelve, when his or her thymus is in full flower. Although some of the functions of the thymus actually get transferred from the thymus to other areas-such as the lymph nodes and bone marrow-as we get older, so that we can continue to make lymphocytes, there's still good reason for thinking that the steady shrinking of the thymus is bad news and heralds the eventual decline and fall of our immune system.

The good news is that three of the pro-longevity hormones I'll be telling you about—DHEA, melatonin, and growth hormone—can slow or, according to some research, actually reverse some shrinkage of the thymus. By so doing, they may slow, perhaps even halt, the decline of immunity with age. And a body that can defend itself against illness is a body that is far more likely to live into a second century.

In Charge of the Furnace

The next stopping point on our endocrine tour of the body is the thyroid, a butterfly-shaped gland about two inches wide and weighing about an ounce, which is located just beneath the voice box at the front of the throat. This remarkable little organ regulates our metabolism. That is to say, it controls the production of energy in our cells. When the fuel from food and stored fat is combined with oxygen in our cells, chemical energy is produced. That is what powers movement, body heat, cellular activity, muscular activity, growth, healing, circulation, brain function, and every other function necessary for life. We'll talk in detail about the thyroid—its proper functioning, its occasional disorders—elsewhere.

Thyroid hormone sometimes diminishes unduly with age, a condition called hypothyroidism. Less often, the thyroid becomes overactive and produces excessive thyroid hormone. The effects of either state can be quite damaging to one's health. A person with insufficient levels of thyroid hormone (hypothyroidism) will feel sluggish and cold, will gain weight, and will experience a slowdown in most of the body's vital functions. Overproduction of thyroid hormone (hyperthyroidism) causes fatigue, anxiety, tremulousness, sweating, weight loss, and sometimes heart failure.

Fortunately, modern medicine is quite capable of normalizing thyroid production or supplementing inadequacies as needed. More problematic is diagnosing the difficulty to start with. Controversy swirls around the most effective methods of determining thyroid malfunction. I'll be talking about these methods at some length. A malfunctioning thyroid is definitely not conducive to good health and longevity.

The thyroid gland also produces calcitonin, a hormone that regulates bone formation and various other functions in the body. Calcitonin is a fairly recent discovery and is not yet fully understood. It is sometimes admininstered as a treatment for osteoporosis and bone pain.

And Now for the Command Centers

The thyroid gland's production of hormone is controlled by another hormone, TSH (thyroid-stimulating hormone), which is itself a product of the pituitary gland. Many a medical writer has somewhat colorfully termed the pituitary the body's "master gland." I agree with that description. Once we arrive at the pituitary, we truly have reached a higher order of endocrine gland.

With a few exceptions, such as growth hormone, the pituitary does not produce the hormones that do the heavy labor of regulating physical processes. Instead, it produces hormones that stimulate other glands to produce hormones.

The advantages of such a system are plain. The pituitary is the guardian of a balanced production of endocrine chemicals. It functions much like the thermostat in your home to regulate heating or cooling systems. If the body begins to produce too much estrogen or testosterone, too much thyroid hormone, or too much cortisone, then the pituitary lowers its output of stimulating hormones, and endocrine production in the lower glands declines. If hormone levels are too low, then the chemical message causes the "thermostat" to be turned up. In medical language, this is called a feedback system, and, if you are healthy, it works beautifully.

The pituitary is a small organ at the base of the brain, hidden and protected in the middle of the head. It weighs less than a gram (one-fortieth of an ounce) and is connected by a thin stalk to the hypothalamus, which is the lower-most part of the brain itself. Perhaps the hypothalamus, as part of the brain, should be called the master gland! These two glands function in such close interconnection that they can hardly be thought of apart. The hypothalamus has sensors that detect circulating blood levels of the many specific hormones that the pituitary controls. In response to the information, it sends chemical messengers to the pituitary to regulate production by the lower endocrine centers up or down as needed.

The hypothalamus really is the body's thermostat—and quite literally so in matters of temperature. We only function efficiently when our temperature is within a degree or so of the ideal 98.6 degrees Fahrenheit (37 degrees Centigrade), which is the conventional number quoted in the textbooks. Each of us may vary from that slightly. But if our temperature is more than one degree above or below our personal ideal, we begin to experience symptoms of malfunction. The hypothalamus has a whole range of techniques for bringing us back to normal, starting with the most obvious: shivering to heat us when we're cold and perspiring to cool us when we're hot, and endocrine glands to produce their hormones. Thus by means of a hormone called ACTH (adrenal cortical stimulating hormone), the pituitary governs the output of cortisone and other specific adrenal cortical hormones by the adrenal gland. In a similar fashion, it directs the production of the sex hormones through pituitary-controlling hormones called gonadotrophins (trophic means "to stimulate the growth of").

More delicately, the hypothalamus signals the pituitary to signal the thyroid that something's amiss. And the thyroid, through its control of energy release with thyroid hormone, definitely has the capacity to do something about it.

Before we go on to the last endocrine gland, the pineal, we must mention that the pituitary has another function and releases another hormone that has a major function throughout the body all on its own—human growth hormone (HGH). It is rather ironic that this is the substance that more obviously than any other seems capable of altering human aging. Until just a few years ago, HGH was considered a profoundly uninteresting and nearly unnecessary hormone once we reached adulthood. Perhaps the name was part of the confusion. Clearly needed for the growth of children, what was the point of a "growth" hormone once we had achieved our full growth?

We now know that HGH is vitally necessary all through life; it's your body's all- purpose repair and maintenance hormone. HGH is actually misnamed. It should be called the "repair and maintenance" hormone. Thyroid deficiency in childhood likewise results in dwarfism, but we do not call thyroid a "growth hormone."

The source of our education is people who lost their pituitaries through trauma or surgery or who, for some congenital reason, are unable to produce growth hormone. When that happens in childhood, growth virtually comes to a halt. Before growth hormone became available, such children matured as dwarfs, the so-called "Tiny Tim" syndrome. In the 1970s, growth hormone extracted from the pituitaries of human cadavers became available in minute quantities and was used exclusively for the clinical treatment of children with the most severe growth deficiencies. Then in 1985, genetic engineering produced growth hormone from recombinant DNA, and the potential supply of the hormone became limitless. Without that development, it's quite likely we wouldn't have felt inspired to write this book, for it now appears that HGH is perhaps the most powerful pro-longevity hormone so far uncovered.

You see, since 1985 it has become clear that, important as growth hormone is to children, it is equally important to adults, but in a different way. The children who grew to normal size with the aid of supplemental HGH have found after they were taken off the hormone that was initially given to promote growth, the developed a different set of problems as HGH-deficient adults. Muscle strength and energy was low. Cell regrowth, repair of injuries, and upkeep of major organs declined. Adults who lose their pituitaries due to surgery or accident suffer these same problems, even if they are receiving supplements of all the other hormones for which the pituitary is responsible. This is starting to change for those who are lucky enough to have physicians who can obtain and will prescribe HGH for them. At another page on this website, we'll look at some of the extraordinary transformations—virtual rebirths of vitality—that growth-hormone-deficient adults have enjoyed once their deficiency is corrected. But remember, HGH declines with age in virtually everyone.

The significance of all this for you and me is that, once we reach old age, we are by definition "growth-hormone- deficient adults!"

Your Body's Clock?

Finally we come to the pineal, which has been and to some extent still is the body's mystery gland. As far as we know, the pineal has only one function: to produce the hormone melatonin. A spate of books published recently, combined with media coverage, has insured that very few readers will be unaware that melatonin is supposed to be good for you. I also believe that it is good for you, and it will be discussed elsewhere. What we don't know for sure is whether the pineal, through its release of melatonin, is also important in actually regulating the body's rate of aging. There is interesting and suggestive evidence from animal studies indicating it just might have that function.

THE WHOLE PICTURE

Looking at the glands we've described above, you will see a very elegant, complex, and interrelated system that controls the most vital parts of our physical and mental functioning. The so-called vegetative functions such as digesting, breathing, and blood circulation tend to be more autonomous, but even those rely on a proper balance of hormones, to some extent. Our most important bodily functions are regulated by our endocrine hormones without our even thinking about it.

Need to burn fuel for heat and energy? Your thyroid will conscientiously command the rate of production, acting in response to guidance from the hypothalamus and the pituitary. Although thyroid problems are not uncommon, for many of us they will never occur. Thyroid does not decline predictably with age in everyone, but about 20% of the population will eventually becomes deficient.

If you must suddenly dodge danger or hasten to the rescue a loved one? Your adrenals will release adrenaline quicker than a flash. And so on, down the whole list of important functions we've been considering.

Now, what goes wrong as we get older? Not everything, happily. We still make adrenaline when in some great crisis it's required. If we're not afflicted with diabetes, our pancreas continues to make insulin and our tissues respond to its effects—although some degree of insulin resistance occurs in most adults past middle age, especially with weight gain.

But each and every one of us will have four different endocrine hormones that decline steadily and predictably with age. These are 1) human growth hormone (HGH), 2) DHEA, 3) melatonin, and 4) the major sex hormones, testosterone in men and estrogen and progesterone in women. The rate at which these hormones decline differs from person to person. By and large, the drop is drastic. An average adult will have lost more than 80 percent of at least three of these hormones on reaching the age of 75.

Studies have shown that these declining hormones are at particularly low levels among the inhabitants of nursing homes and in victims of heart attacks, strokes, senility, and cancer. Even before we consider the question of whether hormone replacement for all of these missing natural substances can extend life, it seems obvious that the millions of individuals who make it into their eighties and nineties would be living far more comfortable and competent lives if their hormone levels were closer to what they had been when they were young adults. I consider quality of life to be just as important as longevity.

Some scientists have speculated that the loss of these hormones may be a necessary adaptation to the increasing weakness and inefficiency of our aging metabolism. Clinical experience and many scientific research studies on replacing those hormones in the elderly indicate that any potential risk involved in hormone supplementation is small when measured against the well-established advantages. And those advantages are of such a nature that they both improve the quality of life and also increase the probability of living longer.

For instance, among the most common and tragic causes of disability and death in the elderly are bone fractures, particularly broken hips. Yet we now know that estrogen supplementation dramatically decreases bone loss in women, as does testosterone replacement in men. Growth hormone also appears to increase bone density in both sexes, while the increased muscle strength and alertness that it produces, together with improved balance and coordination, are also important in preventing falls, the most common cause of bone fractures in the elderly.

DHEA and melatonin may be equally as important for maintaining quality of life in an older body. Moreover, there is a flood of evidence appearing in scientific journals showing that—in addition to all their other benefits—these hormones deliver formidable reinforcements to the immune system. As you grow older, your immune system is, frankly, slowly dying. This can be reversed. As little as five years ago, no one suspected such a reversal was possible.

This survey and overview of our endocrine glands should give you a sense of the big picture. Elsewhere on this Internet website you can Now it's time to look at the pro-longevity hormones one by one.