It is often necessary to make decisions on the basis of information sufficient for action, but insufficient to satisfy the intellect.

--Immanuel Kant (1724-1804), German philosopher

I hear it all the time from my patients: "Dr. Smith, I'm eating just like you told me to--lots of grains, beans, fruits, and vegetables, nothing fatty or sugary. Now you're recommending supplements, too? Taking so many pills just doesn't seem natural. If Mother Nature felt I needed extra nutrients, wouldn't she have put them in my food?"

It's a perfectly valid question, and one which you may have wondered about at one time or another. I'll tell you exactly what I tell my patients: If you want to fight disease and achieve maximum life span, you can't do it with diet alone. You need the extra nutritional boost that only supplements can provide.

Lots of folks take supplements nowadays. For as many as 40 percent of American adults--about 100 million of us--these pills have become nutritional staples. They're also the backbone of a thriving, $10-billion-per-year industry.

In many ways, supplements are to humans what fertilizer is to plants. Give a plant adequate amounts of sunlight and water, and it will survive. Add some nutrient-rich fertilizer (organic, of course), and the plant will thrive.

For us humans, the same principle applies. A healthful, balanced diet supplies the body with sufficient nutrients to carry out routine tasks. Supplements such as vitamins, minerals, essential fatty acids, phytochemicals, and more enrich the body's internal environment to fortify cellular protection, repair, and regeneration and support the Renewal process.

Mother Nature's Ulterior Motive

Of course, supplements, at least as we know them, haven't been around all that long. How did our ancestors survive without them? To be painfully blunt, they didn't.

You see, Mother Nature has never cared about optimum health. Nor has she concerned herself with longevity. Her main objective is survival and propagation of the species. So she programmed us humans to survive on even the crummiest diet, nutrition-wise, into our twenties, when we're old enough to reproduce. Beyond that, we're on our own.

This genetic twist is a throwback to primitive times, when supermarkets and refrigerators didn't exist and food was not always plentiful. Those who could stay alive on very slim pickins had a tremendous survival advantage.

Over thousands of years, one generation has passed its "survival genes" on to the next. So thanks to our ancestors, we are equipped to subsist on minuscule amounts of the essential nutrients, just in case a famine comes along. But as I said before, this insurance policy remains effective only into our twenties--just long enough for us to reproduce. It includes no provision for aging.

By the time we reach our twenties, we have established lifelong eating habits. And because our survival genes have protected us from the adverse effects of our dietary transgressions, we have no reason to believe that what we're eating (or not eating) is doing us any harm. So we continue feeding ourselves nutritionally vacant junk foods, unaware that they're quietly eroding our health. Often we don't see the effects for several decades.

The point here is this: Even with a lousy diet, we can remain fairly healthy through our first 30 to 40 years of life. But if we want to achieve optimum health and maximum life span, the nutritional bare bones just won't cut it. We need to eat nutritious foods, and we need to take supplements.

In the Red

In part 2, I introduced you to the Anti-Aging Diet, which is designed to get your dietary habits on track for Renewal. If you're like most Americans, you haven't been eating as healthfully as you could.

The standard American diet gets 45 percent of its calories from fat and another 35 percent from sugar. In other words, 80 percent of the calories we consume provide none of the nutrients that our bodies need. Incredibly, despite our dietary excesses and an epidemic of obesity, as a nation we are underfed.

One interesting study examined the incidence of vitamin deficiencies in a randomly selected group of hospital patients. Using the Recommended Dietary Allowances (RDAs) as the standards, 88 percent of the 120 patients came up short in at least one vitamin. Many showed multiple deficiencies. Only 12 percent tested at "normal" levels.

Diet is not the sole force behind the national plague of nutrient deficiencies. Other factors include the following:

• Alcohol consumption (depletes B vitamins, vitamin C, most minerals, and antioxidants)

• Allergies and infections (deplete vitamins A and C and zinc, among other nutrients)

• Exposure to air pollutants and other toxins (depletes antioxidants)

• Smoking (depletes antioxidants)

• Stress (depletes all nutrients, especially B vitamins and vitamin C)

Some people simply require more of certain nutrients than the general population does. Children and older adults tend to need a bit extra, as do pregnant women. Others with increased nutritional demands include those who diet and those who exercise strenuously.

Then, too, some foods that we eat because we think they're healthful have actually been stripped of their nutrients before they get to our plates. Whole wheat loses 75 percent of its B vitamins, minerals, and fiber when it is milled into flour. Likewise, rice loses most of its vitamins, minerals, and fiber when it's polished to turn it from brown to white. Even the soil that these and other plant-derived foods grow in is often nutrient-depleted.

Short by Any Standard

Nutrient deficiencies have become the norm in the United States. As the following statistics suggest, many of us are having a hard time fulfilling our bodies' most basic nutritional needs. The percentages in this table are based on the Recommended Dietary Allowances, which many experts now say are inadequate. Imagine how poorly we'd fare if the required nutrient intakes were higher.

The Price of Poor Nutrition

Initially, the body hints of a nutrient shortfall with any of a hodgepodge of minor symptoms: fatigue, weakness, insomnia, irritability, nervousness, depression, poor concentration, memory loss, aches and pains, recurrent infections, allergies, circulatory problems, and just not feeling good. These are the vague symptoms that drive patients to doctors, and drive doctors up a diagnostic tree. Because most conventionally trained physicians have little education or experience in nutrition, they're unable to make the connection between a patient's complaints and a nutrient deficiency. Then when the test results come back normal (as they usually do in such cases), the symptoms tend to be dismissed as "all in your head"--or, even worse, as "a natural part of aging."

If doctors do prescribe treatment, they usually bypass nutritional supplements in favor of drugs such as anti-inflammatories, antidepressants, tranquilizers, and the like. These not only mask symptoms but also deplete nutrient stores even further. This accelerates the degenerative process, which is the forerunner of disease and aging.

Chronic nutrient deficiencies invariably lead to serious health problems. Data collected from large populations show that as the availability of nutrients declines, the frequency of illness increases. Unfortunately, when heart disease, cancer, diabetes, osteoporosis, arthritis, or some other serious deficiency-driven condition develops, neither doctor nor patient is likely to realize that the symptoms had begun years before.

Explaining the Exceptions

Ultimately, nutrient deficiencies deprive us of years of life. The average American survives only into his seventies or, if he's lucky, his eighties. Yes, there's always someone who beats these odds and lives to a ripe old age--a 101-year-old Aunt Edna or Uncle Frank who eats nothing but junk food, swigs coffee all morning and downs a shot of whiskey before bed, smokes two packs of cigarettes a day, and has never swallowed a single multivitamin. The fact that such folks live as long as they do is truly remarkable. Unfortunately, they give the rest of us an opportunity to rationalize our own eating habits and lifestyles.

Very few individuals are so genetically well-endowed that they need only stay out of harm's way to survive to age 90 or beyond. For every one of them, there are thousands of the rest of us. And if they took better care of themselves, they could last even longer. Why, Aunt Edna or Uncle Frank might live to see 120.

Shoring Up with Supplements

All of us can take a giant leap toward longevity just by taking supplements. Supplementation not only protects against deficiency but also bridges the gap between average nutrition, which culminates in premature death, and optimum nutrition, which extends life span by decades. The extra nutrients that supplements provide prevent marauding free radicals from harming healthy cells, speed the repair and regeneration of damaged cells, and facilitate Renewal. The upshot of all this is a longer, healthier, more vital life.

Supplements are intended to enhance the nutrient density of your diet. By nutrient density, I mean the ratio of micronutrients (vitamins, minerals, and other essential nutrients) to macronutrients (carbohydrates, protein, and fat). The higher this ratio, the healthier your diet.

The Anti-Aging Diet, for instance, has a naturally top-notch nutrient density. Supplements boost the ratio even higher because they supply nothing but essential nutrients--no carbohydrates, protein, or fat.

The combination of a nutrient-dense diet and supplements creates an environment conducive to peak cellular performance. When your cells thrive, your body thrives--and that translates into extra decades of optimum health.

Reading between the (Requirement) Lines

So which nutrients do you need, and in what amounts? Opinions vary. The Recommended Dietary Allowances have been the accepted standard since the early 1940s. But now nutrition researchers generally agree that the RDAs fall far short when it comes to preventing chronic degenerative diseases, promoting optimum health, and extending life.

The RDAs were first established for the purpose of protecting people against severe nutrient deficiency diseases such as beriberi (thiamin deficiency), pellagra (niacin deficiency), and scurvy (vitamin C deficiency). Even though they've been updated several times over the years, the RDAs still do not acknowledge the link between chronic marginal nutrient deficiencies and chronic degenerative diseases. Yet thousands of studies have shown beyond a reasonable doubt that long-term low-grade malnutrition causes or aggravates virtually all of our deadliest illnesses, including heart disease, cancer, diabetes, osteoporosis, and autoimmune disorders (in which the immune system turns against the body). It also contributes to a host of less-serious health problems that nevertheless erode one's quality of life, including cataracts, hearing loss, insomnia, and rheumatism (pain and inflammation in muscles and joints).

Just as poor nutrition can precipitate disease, peak nutrition can prevent it. Here again, the RDAs are woefully inadequate. They advocate nutrient intakes well below the levels that overwhelming scientific evidence supports as necessary to protect against heart disease, cancer, and all the other conditions mentioned above.

The Real Ideal Intake

Achieving the dual goals of optimum health and maximum life span requires nutrient intakes beyond what the RDAs advocate and what diet alone can supply. I recommend replacing the outmoded RDAs with the Optimum Daily Allowances, or ODAs.

The ODAs are the ranges of nutrient dosages prescribed by nutrition-oriented doctors. Each range represents a consensus of experts and is based on thousands of published peer-reviewed studies that determined the nutrient levels necessary to prevent and treat chronic degenerative diseases.

While the RDAs provide only short-term protection against serious acute nutrient deficiencies, the ODAs are necessary to sustain optimum health and support Renewal. Take vitamin E as an example. The human body can get along just fine on the RDA of 30 international units (IU). But it needs at least 13 times that amount to have a fighting chance at staying disease-free and lasting 120 years.

Diet Won't Do It

The ODAs far exceed the nutrient levels that diet alone can supply. Supplementation is absolutely essential.

Again, let's use vitamin E as an example. The RDA of 30 IU--the amount necessary to stave off deficiency-related illness--is difficult to get from even the best food sources. So you can imagine the challenge of meeting the ODA of 400 to 1,600 IU without the aid of supplements.

Sunflower seeds have more vitamin E than any other food. To get 400 IU of the nutrient, which is the amount provided by a typical multivitamin or a vitamin E capsule, you'd have to eat 1½ pounds of seeds every day. Even the most ardent sunflower seed fan would find this a bit hard to swallow.

Other vitamin Erich foods fare even worse. To meet the ODA, you'd have to eat one of the following every day.

• More than 2 pounds of wheat germ

• More than 3 pounds of almonds

• 10 pounds--about 40 ears--of fresh corn

• More than 33 pounds of spinach

• 50 pounds of broccoli or butter

Hmmm . . . hope you're hungry.

You have to admit, getting your vitamin E in pill form seems a lot easier (not to mention a lot less filling). And believe me, E is one nutrient that you don't want to run low on. An antioxidant, it scavenges free radicals, stimulates the immune system, protects against cancer and cardiovascular disease (such as hardening of the arteries, angina, heart attack, and stroke), and inhibits the formation of cataracts. For these and many other reasons, vitamin E is a key player in the Renewal process.

Another key player is vitamin C. Like vitamin E, vitamin C is an antioxidant with proven anti-aging effects. It scavenges free radicals, bolsters the immune system, speeds healing, protects against infection, lowers cholesterol, and helps prevent cancer and atherosclerosis (hardening and clogging of the arteries).

To reap these benefits, you need much more vitamin C than the RDA of 60 milligrams. This amount may prevent scurvy, a nutrient deficiency disease that's virtually unheard of these days, but it won't support Renewal. For this, you need the ODA of 1,000 to 10,000 milligrams.

Suppose you're aiming for the low end of the ODA range. To get 1,000 milligrams of vitamin C from foods alone, you'd have to eat 5 cantaloupes, 10 cups of strawberries, 12 bell peppers, 12 cups of raw broccoli, 13 grapefruit, 15 oranges, 40 baked potatoes, 50 red ripe tomatoes, or 62 cups of raw spinach. Every day. And these are the best food sources of vitamin C.

Personally, I recommend an even higher vitamin C intake--2,000 to 6,000 milligrams a day. I base this dosage on reams of research reports as well as on 20 years of clinical practice, during which I've prescribed a great deal of vitamin C to a great many patients for a great many conditions. With the newer, polyascorbate form of vitamin C (called ester-C), you don't have to worry about gastric upset and diarrhea--even at higher doses. This form has more than twice the bioavailability of ascorbic acid, so you need only half as much--1,000 to 3,000 milligrams a day.

For one final example, let's take a look at the carotenoid clan. More than 600 carotenoids have been identified so far. The best known of the bunch is beta-carotene, which your body converts to vitamin A. In fact, both beta-carotene and vitamin A protect against cancers of the larynx, lungs, esophagus, gastrointestinal tract, colon, rectum, breasts, cervix, bladder, prostate, and skin.

To get even a modest daily dose of beta-carotene--say, 20,000 international units, which is actually less than the ODA--you'd have to consume 2 cups of collard greens, 4 large carrots, 7 cups of spinach, 8 cups of broccoli, 10 apricots, 14 cups of prunes, 15 peaches, 30 cups of yellow squash, or 40 cups of zucchini. You're better off taking a supplement that contains mixed natural carotenoids, not just beta-carotene. This way, you're getting the healthiest combination of carotenoids for superior disease-defying powers.

The Recommended Dietary Allowances (RDAs) have come under fire as being too low to prevent chronic degenerative diseases and slow aging. Nutrition-minded experts advocate the Optimum Daily Allowances (ODAs). Here's how the two intakes compare for key anti-aging vitamins and minerals.

Note: The RDAs are for people ages 25 to 50. The ODAs are appropriate for adult men and for adult women who are not pregnant or lactating. They are not intended for children under age 15.

*The amount listed is the Estimated Safe and Adequate Daily Dietary Intake, as recommended by the Committee on Dietary Allowances of the National Academy of Sciences' Food and Nutrition Board.

*People who are taking blood thinners should consult their doctors before taking supplemental vitamin E.

**Supplemental magnesium may cause diarrhea in some people.