The Search for the Anti-Aging Diet
New studies suggest healthy eating may add years to your life.
New studies suggest healthy eating may add years to your life.
"What's the secret to a long and healthy life?" When I asked my great-grandmother that question on the occasion of her 90th birthday, her answer took everyone by surprise. "I always make sure to eat the fat and gristle off meat," she said.
Fat and gristle?
We all laughed at the time, Great-Grandma included, but no one dared argue with her. What her pet theory lacked in scientific evidence it more than made up for by personal example. She lived a jolly, healthy, sharp-minded life well into her nineties.
Since then, whenever the headlines tout a new breakthrough in longevity-whether it's green tea, red wine or a supercharged antioxidant supplement-I haven't paid much heed. Lately, though, I've begun to wonder if it isn't time to take a fresh look at the field of anti-aging research-and not only because I'm halfway through my fifties.
Increasingly, serious scientists have joined the quest for a fountain of youth. The National Institutes of Health is spending millions to explore ways to increase life span, including research into drugs, nutritional supplements and calorie restriction. Last year, headlines announced that a new anti-aging drug, based on a substance called resveratrol found in wine and grapes was being tested in people. If the booming science of anti-aging medicine has turned up anything that really works, I decided, I want to know about it.
So a few months ago I set off on my own search for a fountain of youth. From the start I decided to rule out things like potions of mysterious-sounding Chinese herbs, anti-aging vitamin formulas and injections of pituitary-gland extract at mountainside Swiss clinics. Maybe they work, maybe they don't; so little evidence exists either way that the claims are almost impossible to evaluate. What I really wanted to know was simple: can the foods we eat and the way we live make a measurable difference in life span? Beyond that, is there any way to actually slow the hands of time and push the limits of longevity?
I decided to start my investigation with the people who should know best-those who live the longest.
Secrets of Long Life From Around the World
For years scientists have been trekking the globe in search of communities of people rumored to live unusually long and healthy lives, trying to pinpoint their age-defying secrets. In the last few decades, they've come up with a handful of promising candidates. For example, research suggests that olive oil (see below) has helped the Greeks beat heart disease. For native Inuits of Alaska, diets containing extraordinary amounts of fish provide cardiovascular protection. The secret of longevity on the San Blas islands, off the coast of Panama, may be the most unexpected-and welcome-of all: chocolate, which happily turns out to be a rich source of compounds that help keep blood vessels healthy.
But some of the most compelling findings on longevity and diet comes from the islands of Okinawa in southern Japan. People here are five times as likely to live to 100 than people in the United States or other industrialized countries. (In Okinawa there are about 50 centenarians per 100,000 people versus 10 in 100,000 in the U.S. and most other developed countries.)
When I contacted Bradley Willcox, M.D., co-principal investigator of the Okinawa Centenarian Study, to ask what accounts for the Okinawans' longevity, his answer startled me. "Sweet potatoes," he wrote back. It turns out that sweet potatoes are a staple in the Okinawan diet, along with bitter melon (a tropical fruit often used in stir-fries) and sanpin tea (a blend of green tea and jasmine flowers). All three foods are exceptionally rich in antioxidants, which may help protect against cellular wear and tear from unstable oxygen molecules generated by our body's biochemical processes. Although researchers still aren't exactly sure why we age, one theory is that oxygen radicals keep chipping away at healthy cells, damaging and ultimately destroying them. The antioxidant theory may help explain why another group recognized for exceptional longevity-the Seventh-Day Adventists-typically outlive their neighbors by four to seven years. Their religious denomination, founded in the U.S. in the 1840s, emphasizes healthy living and a vegetarian diet starring vegetables, fruit, whole grains and nuts-all foods packed with antioxidants.
Dinner at the Longevity Cafe
The more I poked through the research, the longer my list of age-defying foods became. Wine or other alcoholic beverages deserve a place at the table; they've consistently been associated with lower mortality, as long as they're consumed in moderation. Blueberries, too, as they've been shown to ward off age-related brain impairments.
I was hoping to add an item or two to the list when I put in a call to Katherine L. Tucker, Ph.D., director of the nutritional epidemiology research program at Tufts University. Tucker has been sifting through 50 years of data from the Baltimore Longitudinal Study of Aging, the longest-running study of aging in the world. When I asked her what foods have popped up in her findings, she gently steered the question in a different direction. What mattered more than single foods, she said, was overall food patterns.
"It's always been tempting to look at a particular food and then home in on what it contains. That's how a lot of nutrition science has been conducted," she explained. When fruits and vegetables rich in beta carotene showed up in many studies, for instance, researchers rushed to test beta-carotene supplements-experiments that went famously wrong when the pills offered no special benefits and posed some danger. The experience encouraged many nutrition scientists to go back to studying eating patterns, since people eat foods in combination, not one at a time.
Tucker pointed to results from a recent analysis she did of 501 men from the study. Over time, those who helped themselves to lots of fruits and vegetables were less likely to develop heart disease and more likely to be alive at the end of 18 years of study. Each serving of fruits and vegetables was associated with a 6 percent reduction in risk of death from any cause. Men who limited their saturated fat also reduced their risk of heart disease. But far and away the most impressive benefits fell to men who served up fruits and vegetables and cut back on saturated fat: they slashed their risk of dying of heart disease by 76 percent and of any cause by 31 percent during the study period.
Current health recommendations don't stop with fruits and vegetables and saturated fat, of course. Most of us know the advice by heart: 1) Get plenty of whole grains; 2) Eat fish a couple of times a week; 3) Eliminate trans fats; 4) Take a glass of wine with dinner if you'd like; 5) Don't smoke. What's the payoff for following all the best advice to the letter? To find that out, researchers at the Harvard School of Public Health looked at more than 84,000 women enrolled in the Nurses' Health Study. Those who got a gold star for following each of these five "commandments" cut their risk of heart attacks and other coronary events by a spectacular 82 percent.
Because so many variables are involved, scientists can't say exactly how many extra years of life you or I will gain by eating well and staying active. But when I asked Harvard nutrition scientist Meir Stampfer, M.D., Ph.D., he estimated that the women in the Nurses' Health Study who followed all the best health advice might be adding an additional 14 years to their lives. Joan Sabaté, M.D., Ph.D., chair of nutrition at Loma Linda University, told me the Seventh-Day Adventists add an extra 10 years to their lives, on average, thanks to five lifestyle factors: being vegetarian, not smoking, exercising frequently, maintaining a healthy weight and eating lots of nuts.
How to Live to be 120
A lifestyle that helps avoid chronic health problems isn't the only thing that determines how long you live, of course. Genes, too, help decide whether one's life span ends up being average (which is about 78 in the United States) or extraordinary (like that of Frenchwoman Jeanne Calment, the oldest person on record, who died in 1997 at age 122). If I manage to live into my nineties, the genes I inherited from my gristle-eating great-grandmother will be partly to thank for it. Thomas Perls, M.D., who directs the New England Centenarian Study, believes that good health habits may be enough to carry many of us into our mid-eighties. To live longer than that, though, we need lucky genes.
But is that the whole story? What about that most elusive fountain of youth-a way to actually slow the aging process and extend the limits of longevity? A growing number of experts think they've found it. For years, in fact, researchers have been aware of a sure-fire way to put the brakes on aging.
In 1935, a team of Cornell University nutritionists discovered that mice fed one-third fewer calories than normal lived about 40 percent longer than mice that ate as much as they wanted. Since then, scientists have tested a Noah's ark of creatures-from yeast cells and fruit flies to monkeys. In most studies, calorie restriction appears to increase life expectancy and protect against a host of diseases. Well into old age, animals typically remain more active and younger-looking, as well.
Scientists don't know exactly why cutting calories may lengthen life, but the leading theory goes like this: When calorie intake falls short, cells sound an alarm, switching their priorities from reproduction to repair and maintenance, fending off genetic damage and the wear and tear caused by the effects of unstable oxygen molecules. Controlling this switch, researchers have learned over the past few years, are a class of enzymes called sirtuins, which affect how energy is delivered to cells. In a 2006 experiment straight out of science fiction, University of California, San Francisco, biochemistry researcher Cynthia Kenyon, Ph.D., tinkered with the equivalent gene in roundworms. The result: a mutant species with a life span six times longer than normal.
Eat Less, Live Longer?
Maybe gene manipulation will allow us to live to 200-someday. Until then, there's calorie restriction (CR). Three large studies are under way to test the principle in people. Early findings show promise. In 2007, researchers at Washington University in St. Louis reported that CR improved heart function and lowered inflammation levels in a group of volunteers-two signs that could mean better health and longer life down the road. In a study of 48 volunteers, Eric Ravussin and his colleagues at Louisiana State University's Pennington Biomedical Research Laboratory found that after six months those men and women who cut calories by 25 percent reduced their insulin levels and their core body temperature-two changes associated with longevity. They also had fewer signs of the kind of chromosomal damage that is associated with aging and cancer.
Clinical trials are far from proving that CR dramatically extends life span in humans. Still, an estimated 50,000 Americans subscribe to CR, a practice popularized by Roy Walford, M.D. Walford, a pathologist at UCLA, wrote several books-including Beyond the 120-Year Diet-on the health benefits of eating a low-calorie, high-nutrient diet. (Walford died in 2004, at age 79, from complications of Lou Gehrig's disease.)
Peter Voss, 53, is an expert in artificial intelligence who runs a start-up firm in Los Angeles. A Google search led me to Voss's lively website about his experiences with CR (optimal.org), which he began in 1997. He now consumes just 1,850 calories daily, which he guesses is about one-third less than what he ate more than a decade ago. "The more I read about calorie restriction, the more interested I became, until I finally decided to give it a try," he told me when I reached him. Five foot 10 inches tall, he now weighs 130, down from 155 pounds 10 years ago. His blood pressure, good to begin with, resembles that of an active teenager, about 100/60. His triglyceride and cholesterol levels are rock bottom.
In the beginning Voss scrupulously counted calories and scoured nutrient labels. Now he monitors his progress by keeping his weight stable. Voss's diet is Spartan by any standard. Steel-cut oatmeal with fruit and skim milk is a special treat. But Voss insists that he isn't always hungry. "I eat whenever I feel like it," he says. Instead of reaching for a cookie for a snack, however, he crunches a carrot or a red pepper. At restaurants, he sticks with appetizers or a first-course salad. His girlfriend, a marathon runner, also follows a CR diet, which probably helps him stick with the program.
There are downsides. Calorie restriction reduces testosterone levels, which in men can mean lower libido. (Researchers don't have much data about the way CR affects female hormones.) Voss is now so thin that sitting on a hard chair gets uncomfortable. But he insists he still has all the energy he needs to work the 14 hours a day required by his company, and to squeeze in an hour or so of power walking most days.
Not everyone thinks CR will buy Peter Voss much extra time. Recently, John Phelan, Ph.D., a researcher at UCLA, published a mathematical model predicting that calorie restriction is likely to offer at best a 7 percent increase in human life expectancy. As evidence he pointed out that the average Japanese male consumes about 2,300 calories a day. Men on Okinawa consume about 17 percent fewer calories-very close to Peter Voss's 1,850 a day-but they only live a little less than a year longer than Japanese mainlanders. Calorie restriction may have its most dramatic effects in species that have experienced periodic famines, forcing them to evolve extreme measures to shut down reproduction and focus on staying alive until food supplies return. We humans, naysayers argue, aren't likely to be among them.
Still, many researchers are excited about the potential benefits. In August, just back from an Experimental Biology conference where the latest findings on CR were presented, Susan Roberts, Ph.D., who is directing a calorie-restriction experiment at Tufts University, wrote in an e-mail: "The human data on people who are already doing CR themselves is extremely impressive. I was sitting in the meeting virtually ready to sign up…myself!"
Practicing the 80 Percent Solution
That's all I needed to hear. The next day I gave CR a try. For about 14 hours. The experience made me understand why even researchers who are convinced that calorie restriction will extend life span doubt it's of much practical use. Let's face it: it's hard enough to get people to make the changes that are already proven to increase the odds of a long and healthy life, like eating more vegetables and exercising half an hour a day.
There's a delicious paradox here. Research into calorie restriction comes at a time when people around the world are consuming more calories than ever-and packing on the pounds. Calorie-restriction diets may seem extreme. But the truth is, most of us would do well to follow the basic tenet, which is to favor low-calorie, nutrient-rich foods. To offer support and advice for people trying calorie restriction themselves, a group of enthusiasts started the CR Society in 1994 (calorierestriction.org). Their advice is anything but controversial: avoid simple sugars and flours, eat lots of leafy greens and other vegetables, choose monounsaturated fats and omega-3 fats and avoid saturated fat. Peter Voss's typical daily fare is a nutritionist's dream: strawberries with nonfat yogurt, almonds, steamed vegetables, salmon, five-bean chili, peanut butter and bananas. If more of us helped ourselves to a menu like his, we'd be healthier for it even if we didn't cut calories. And probably add years to our lives.
Long before the verdict is in on calorie restriction, in other words, and even longer before effective longevity pills hit the market, there's a lot most of us can do to better our odds of living long and staying active and alert. For my part, I decided to dish up a few extra servings of vegetables, snack on nuts, treat myself to a small square of dark chocolate for dessert and get to the gym a little more often. Oh yes, and to take a page from those long-lived Okinawans, who have been practicing their own simple form of calorie restriction long before modern science came along. According to Bradley Willcox, the Okinawans have traditionally followed hara hachi bu, a custom of eating until they are just 80 percent full. The practice allows them to consume fewer calories without bothering to read nutrition labels-and it means they don't have to obsess about what to eat and not eat but can go about enjoying themselves.
And that, in the end, may be even more crucial to their longevity than, well, sweet potatoes or sanpin tea. Finding delight in family and friends, having something to look forward to every day: studies of centenarians around the world suggest that these intangibles, even more than the specifics of diet, may be the most powerful secret to longevity. The Okinawans have a name for it: ikigai, or "finding your reason to live."