Purported fountains of youth are everywhere these days. By 2009, Americans will be spending more than $70 billion each year on antiaging products and services, according to Massachusetts market-analysis firm BCC Research. “There is a huge swelling of baby boomers who are suddenly facing aging and mortality and who are becoming very interested in longevity,” says Steven Austad, PhD, a professor at the Sam and Ann Barshop Institute for Longevity and Aging Studies in San Antonio, Texas. “People desperately want to stay younger longer.” Although there is no such thing as everlasting youth, our life spans may not be as unyielding as scientists once believed. At the beginning of the 20th century, Americans could expect to live 47.3 years. Now, babies born in the United States in 2005 are projected to live 77.8 years, according to the Centers for Disease Control and Prevention.

Want to reach — or even beat — that milestone? Experts say the aging process isn't set in stone; it's the slow weakening of your body's building blocks, as well as the gradual decline of your natural repair processes. The good news is that this deterioration can be slowed by smart choices, such as eating healthy food and buffering your immune system. “The important thing isn't just how long you are living,” Austad says. “It's also how happy and healthy you are when you are alive.”

Focus on what you eat

The road to a longer life may begin at the dinner table. The secret lies in your genetic code, which instructs the body on how to maintain itself or, when the code is damaged, signals the onset of aging. “Now we know damage to DNA is a main cause of aging in general,” says Vincent Giampapa, MD, cofounder and former president of the American Academy of Anti-Aging Medicine and author of The Gene Makeover: The 21st Century Anti-Aging Breakthrough (Basic Health, 2007). “When we eat carbohydrates, protein, and fats, the process of turning that food into energy creates waste products that result in the creation of free radicals.” These are highly reactive compounds that can trigger processes in the body that damage DNA, leading to physical deterioration and the onset of degenerative diseases. To reign in this wear and tear, get plenty of antioxidants by eating at least five to seven servings of a variety of deep-hued fresh fruits and vegetables daily, and follow these nutritional guidelines to bolster your internal infrastructure.

Cut calories

The antiaging potential of caloric restriction, the process of severely limiting dietary energy intake, has been hotly debated in recent years. Although it's been shown to increase the maximum lifespan of many lab animals, including primates, rats, mice, and spiders, scientists aren't sure why. Some advocates suggest slashing daily calorie intake by 20 percent to 40 percent — a regimen that to many folks sounds impossibly arduous. The trick, says Giampapa, is to focus on a moderate caloric restriction process, one that's “a calorie-restricted diet, but not a volume-restricted diet.” For example, eat six small meals a day instead of three big ones, and significantly up your vegetable intake, because low-starch veggies like broccoli and summer squash fill you up but don't pack major calories.

Cook smarter, not longer

A study published in the Journal of Gerontology in 2007 found that toxins called advanced glycation end products (AGEs) collect and are stored indefinitely in the body as a result of eating overly cooked food. These chemicals, found particularly in fried and grilled meats, as well as in processed foods, have been associated with age-related disorders, including diabetes, vascular disease, and Alzheimer's disease. “The higher the temperature, the longer you cook it, and the drier food is, the more AGEs there will be,” says Jaime Uribarri, MD, lead author of the study and professor of medicine at Mount Sinai Medical Center in New York City. Avoid AGEs by emphasizing whole grains, fruits, vegetables, and fish in your diet, and using cooking techniques such as poaching and stewing, which require lower temperatures and allow food to retain moisture. When you do barbecue, marinate food first and prevent items on the grill from drying out by frequently basting or drizzling them with lemon juice or vinegar.

Take ample C

“Virtually every nutrient you can think of can counter the signs of aging,” says Michael Janson, MD, author of a 2006 review of antiaging supplements published in Clinical Interventions in Aging. Vitamin C, however, is particularly helpful when taken at doses significantly higher than the reference daily intake (90 mg for men and 75 mg for women), says Janson. Vitamin C protects against free radical damage, helps reduce wrinkles and maintain mucous membranes, and is integral to immune function. In one study of people between ages 60 and 80, taking a 500 mg vitamin C supplement every day modestly lowered blood pressure, a finding that may be linked to the nutrient's role in preventing cardiovascular disease and stroke. Janson recommends 1,000 mg per day or more, but higher amounts may cause stomach upset, he says.

Go for the golden root.

An adaptogenic herb long used by Russians and Scandinavians to alleviate stress, rhodiola (Rhodiola rosea) — or golden root — might be the new longevity wunderkind. Adaptogens help the body cope with the effects of stress, and recent research at the University of California at Irvine found that fruit flies fed rhodiola lived 10 percent longer than those not fed the herb. “Although this study does not present clinical evidence that rhodiola can extend human life, the finding that it does extend the lifespan of a model organism, combined with its known health benefits in humans, make this herb a promising candidate for further antiaging research,” says study author, Mahtab Jafari, PharmD. A typical dose is 100-200 mg a day.

Bolster your immunity

You're born with an impressive immune system capable of fight- ing off most of the nasty stuff the environment throws your way. But as you age, that immune system begins to slow down; infections are less readily attacked, causing inflammation that can lead to arthritis, cardiovascular disease, and Alzheimer's disease. When imbalanced, the aging immune system can also mistakenly attack the body. “The immune system is sort of like an army of several million soldiers, and we don't want them using their weapons indiscriminately,” says Mark Liponis, MD, corporate medical director of Canyon Ranch Resorts and author of Ultralongevity (Little, Brown & Company, 2007). “Many of the main diseases Americans are dying from today are caused by malfunctioning immune systems.” Those diseases include cancer, diabetes, and autoimmune diseases, such as thyroid problems, multiple sclerosis, and Crohn's disease. Your best bet, then, is to give your self-defense system as much support as possible.

Sleep on it

Your immune system needs a good night's rest to remain robust. “Sleep is when the immune system finally relaxes and repairs itself,” explains Liponis. Otherwise, the immune system will be weak and won't be able to fight off diseases and infections. In fact, patients who suffer from sleep apnea — a condition that causes multiple sleep disruptions throughout the night — are at increased risk of inflammation and even heart disease. Liponis recommends setting a regular time to go to bed every night, scribbling stressful thoughts in a notepad before you close your eyes, and shutting out distracting light and sounds as much as possible. Aim for an optimal amount of z's: six to eight hours every night.

Slow down and breathe

“We live in a state of time urgency. Your mind jumps from the past to the future to the past to the future, and you don't focus on the present,” says Giampapa. “When you are in this state of time urgency, your cortisol levels just climb higher and higher and higher.” Cortisol, the body's primary stress hormone, eventually weakens the immune system. Giampapa offers a handy relaxation trick: “The easiest thing to do is to focus on slow, deep breathing and visualize something in your mind that helps you stay peaceful, like someone you love, your pet, or your favorite place. That will normally bring you right down.”

Breathing properly can also go a long way toward calming the body and regulating your immune system, says Liponis. Among test subjects in a 2005 study, immune function improved after they attended a mindful-breathing class. Avoid shallow, tense breaths, which send the immune system into overdrive, says Liponis. Concentrate on drawing air deep into the abdomen, allowing the stomach to expand with each breath, and fully exhaling.

Get physical

If you want to live longer and better, break out those jogging shorts. A recent study determined that people who exercised had longer leukocyte telomeres — the parts of white blood cells that shorten with age and eventually lead to cell death. Exercise also showed an anti-inflammatory effect in 4,000 adults who participated in a 2006 study. One reason why exercise may stave off aging is because it naturally increases hormone levels. “As you age, your hormone levels drop, and that changes your body composition, your energy levels, and your quality of life,” says Vincent Giampapa, MD. “Exercise is the easiest, least expensive way to balance your hormones. Twenty minutes of aerobics followed by 40 minutes of weight training or yoga actually changes your testosterone level, your DHEA level, your cortisol level, your thyroid hormone level, as well as a number of other hormones.” But as you get older, you'll need to do it more and more to see benefits, he says. So if you're in your 30s, aim for exercise three times a week; in your forties, four times a week; and so on.

Life-lending supplements 

ALPHA-LIPOIC ACID (ALA) is an antioxidant that helps the body eliminate metals such as mercury. At high doses it may help reverse diabetic damage associated with aging.

Dose» 300-500 mg once a day; up to twice daily for diabetics

COENZYME Q10 Necessary for energy production, this antioxidant helps fight heart failure, lower blood pressure, and protect against Parkinson's and Alzheimer's.

Dose» 100-300 mg once a day

Omega-3 fatty acids: These fats, found in walnuts, flaxseeds, and some fish, help prevent against age-related heart attacks, stroke, and some autoimmune diseases.

Dose» 1,000 mg once a day

Quercetin: By preventing the release of histamines, this flavonoid helps manage allergy symptoms and inflammation — precursors to many age-related complaints. May also lower risk of cataracts.

Dose» 400-600 mg twice a day

Vitamin E: Elderly people with higher vitamin E levels are less likely to show signs of vascular aging.

Dose» 400-800 IU once a day

Sources: Michael Janson, MD; Mark Liponis, MD.