Honey, you need to get yourself some hormones.

--From the movie Fried Green Tomatoes (1991)

At least since the dawn of recorded time, humans have searched for the elixir of youth. Shamans sought the magical potion; herbalists, the miracle plant. Spanish explorer Juan Ponce de León pursued his quest halfway around the world, to what is now Florida. But he needn't have traveled so far from home. As modern-day "explorers" of medicine and science know, the real fountain of youth has been inside the human body all along.

What has the power to keep us youthful and disease-free for a lifetime? Human hormones, the substances naturally produced by various components of the endocrine system: the adrenal glands, ovaries, pineal gland, pituitary gland, testicles, and thyroid gland. Understanding how changing levels of hormones influence the aging process--for better or for worse--gives us tremendous leverage in our bid to slow down and even turn back the hands of time.

By maintaining optimum amounts of certain hormones in the bloodstream, hormone replacement therapy has genuine potential to put the brakes on aging. Already, millions of folks have begun tapping into the anti-aging effects of dehydroepiandrosterone (DHEA) and melatonin, which include enhanced energy, better sleep, improved stress tolerance, and an overall healthier body. And millions of women who are going through or past menopause have discovered the benefits of natural estrogen and progesterone replacement, a risk-free alternative to synthetic hormone replacement.

To some, hormone therapy may seem unproven or even dangerous. Indeed, hormones are powerful substances that must be used properly and carefully. But when taken in amounts that exactly match the body's shortfall--no more, no less--natural hormones catapult out of the questionable quagmire of synthetic hormones and into the realm of safe, scientifically sound preventive medicine.

Chairmen of the Bod

Biochemically speaking, hormones operate differently than vitamins, minerals, and other essential nutrients. Hormones oversee and regulate the complex dance of metabolic activity within your body, while essential nutrients do the actual work (as antioxidants, catalysts, and structural components). If your body were a Fortune 500 company, all of its hormones would sit on the board of directors, while essential nutrients would man the assembly lines. Hormones make the top-level decisions about what will get done, how, when, and by whom. And like top executives, they are quite effective even in small numbers.

Detecting and correcting hormone deficiencies can pay huge dividends in terms of longevity. Maintaining hormone levels comparable to those of our twenties and thirties not only slows aging but also makes us healthier and improves our quality of life. In the next several chapters, you'll discover how hormone replacement can prevent and reverse the physical and mental changes that we usually view as "normal" consequences of getting older: impaired immunity, brittle bones, fragile blood vessels, atrophied muscles, loss of memory, insomnia, weakness, fatigue, and loss of libido.

Can hormone replacement really accomplish all this? Absolutely. By supporting the Renewal process, it helps your body to heal itself faster and protect itself better. So you become healthier--and you live longer.

Giving Nature a Hand

The phrase hormone replacement implies that hormones are missing. They don't actually disappear. Your body simply makes fewer of them.

Once you reach your thirties, your body begins a long--and hopefully slow--decline. Driving this gradual deterioration is the diminished output of hormones by the various glands and organs of the endocrine system. The drop in productivity doesn't just happen, by the way. It is programmed into your genes.

As hormone production slows down, the aging process speeds up. In fact, the rate at which hormone production decreases (or the steepness of the curve, as we scientists say) directly determines the rate of aging. Your body makes less of these crucial anti-aging hormones as you get older.

• DHEA and pregnenolone

• Melatonin

• The sex hormones--estrogen, progesterone, and testosterone

• Thyroid hormone

By restoring these hormones to predecline levels, you can slow and even reverse the aging process. Research has shown that hormone replacement combats disease, revitalizes the body, and primes you for extra decades of life.

Of course, each type of hormone performs a very specific set of tasks within your body. DHEA has perhaps the most profound influence on the aging process. In fact, DHEA therapy alone may extend life span, according to some experts. Melatonin governs the body's sleep-wake cycle and, in supplement form, makes an excellent sleeping aid and jet lag remedy. The hormone also scavenges free radicals, which fights the effects of stress, inhibits the development of cancer, and controls the body's aging clock. Natural estrogen and progesterone combine to ease a woman's passage through menopause as well as to safeguard her health after menopause--without increasing her risk of cancer, as synthetic sex hormones do.

Based on my own research and experience, I'm thoroughly convinced that natural hormone replacement therapy plays an essential part in human health and maximum life span. I count myself among the thousands of doctors around the world who prescribe natural hormone replacement therapy to patients. We use natural hormones in two ways: first, as treatment for specific symptoms (such as estrogen for hot flashes, testosterone for low libido, and thyroid hormone for fatigue); and second, as preventive medicine to compensate for declining hormone production, which forestalls the aging process.

Natural hormone replacement therapy comes with two simple but important rules for its safe and effective use. First, a hormone supplement must have the exact same molecular structure as the hormone that your body produces naturally. Not similar, but identical. Second, the supplement dosage should raise the level of hormone just enough to match the amount that floated around your bloodstream prior to age 30. This is called a physiologic dose, and it's what your body is accustomed to. When hormone therapy backfires, it's because one of these two rules has been violated.

Only Natural Will Do

Close may count in horseshoes, but not in hormone replacement. Your body desires, expects, and deserves the real thing. It cannot be reprogrammed to accept anything less, especially not in such an intimate role.

Synthetic hormones have some of the same benefits as natural hormones. But they also have some undesirable effects. Most notably, the lookalikes upset your finely tuned endocrine system.

Hormone receptors located on the surface of every single cell are designed to recognize and lock onto the hormones that your own body makes. But if a synthetic hormone approaches an empty receptor, the imposter can just as easily attach. There's a price to be paid for this transgression. First, with the lookalike occupying the receptor site, the real hormone cannot hook up with the cell. Second, the lookalike doesn't behave as it should. Like a party crasher, it shows up uninvited and disrupts the action.

The indiscriminate use of synthetic hormones is responsible for some of the most profoundly shocking and woeful chapters in the history of medicine. Fake estrogen and progesterone, for example, have already caused far too many women to develop cancer and to die prematurely. Years before these hormones gained notoriety, diethylstilbestrol (DES)--a synthetic hormone with a molecular structure similar to progesterone--was linked to uterine cancer. In this case, however, the cancer affected the daughters of women who took DES during pregnancy to prevent miscarriage.

Then, too, farmers continue to spray tons of hormone-mimicking pesticides on the public food supply. The pesticide molecules can trigger inappropriate hormonal reactions and the uncontrolled formation of cancer cells.

Lookalike hormones are to blame for a great deal of needless human suffering. Just take a look at the package insert or the Physicians' Desk Reference listing for any synthetic hormone. Pay special attention to the sections labeled "Adverse Reactions," "Precautions," and "Contraindications," where you'll find long lists of side effects. These are your body's way of saying, "What is this stuff? I'm not sure how to use it."

If synthetic hormones are so detrimental to human health and longevity, then why do they stay on the market? Because their natural counterparts, while more effective, are also much less profitable. You see, drug companies cannot patent natural compounds. So they spend millions of dollars on research to develop patentable fakes. Basically, they're trying to reinvent the wheel, but their versions amount to the endocrinological equivalent of wobbling. Second-guessing nature, as the drug companies have, is bound to produce second-rate compounds that are unsafe and more likely to cause adverse reactions. These wannabe hormones are not the same as real hormones, nor will they ever be.

Nature has already done the research to determine precisely which hormones you need. These are the substances that your body is genetically programmed to make. They have sustained you for this long, and they will continue to do so. They simply can't be improved upon.

No amount of experimentation can disprove nature's research or improve upon the hormones that she has created. A little synthetic embellishment of nature's original "recipe" can make a hormone patentable and profitable--as well as toxic. This, we now know, is an invitation to disaster.

Natural hormone replacement supplies exact replicas of the compounds that are manufactured by your body. It offers the same benefits as synthetic hormone replacement, but with none of the inherent risks.

The point is this: Your body has gotten really attached to the hormones and other molecules that it makes for itself. It doesn't like surprises, and it doesn't appreciate substitutes. This is why synthetic lookalikes produce unwanted effects. The real thing never has and never will.

Quantity Counts, Too

For natural hormone replacement to work as it should, the dosage should closely approximate the maximum hormone level maintained by the body. This amount, the physiologic dose, is just what the body needs, as determined by nature over tens of thousands of generations. (A higher amount, called a pharmacological dose, is used to achieve a druglike effect.)

This underscores an important point: Hormone replacement, when administered properly, only restores a hormone to its optimum level. The therapy never advocates taking more of a substance than the body can actually use. Such an overdose could actually create more health problems than it treats or prevents.

The Right Doc for the Job

In the following chapters, I'll be profiling each of the anti-aging hormones and offering some guidelines for supplementation. But because determining the right hormone dosage is so critical, I urge you to consult a doctor who has experience with natural hormone replacement therapy. He can help you set up your own hormone replacement program, monitor its effectiveness, and recommend adjustments as necessary.

Finding the right doctor can be a bit of a challenge. From what I've observed, physicians' attitudes toward hormones can range from skeptical to schizophrenic. For example, many mainstream doctors espouse hormone replacement therapy for women at or past menopause. (Unfortunately, they usually prescribe synthetic hormones such as Premarin, an "estrogen" that's extracted from horse urine, and Provera, a fake progesterone.) But these same doctors express serious reservations about DHEA, pregnenolone, and melatonin--even though the natural forms of these hormones are much safer and better tolerated than the synthetic stuff they're giving to their female patients. "We want more proof," these doctors say. "We want more studies."

Of course, estrogen and progesterone are not the only hormones that decline with age. Nor does diminished hormone output affect only women. So if physicians can embrace estrogen and progesterone replacement, why can't they accept other types of hormone replacement as well?

If your doctor seems reluctant or uncomfortable when discussing natural hormone replacement therapy, you may need to look for someone else.

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Now that you understand the basic principles of natural hormone replacement therapy, let's take a closer look at each of the anti-aging hormones. First up: DHEA and pregnenolone, the dynamic duo that may do more than any other substances to slow and reverse the aging process.