We all know about the kinds of foods that may contribute to shortened, less healthy lives. Pork rinds, charred meat and lard, these kinds of things. But are there foods for living longer?
There is no shortage of people who will be happy to sell you a specific supplement or food that they claim will help you live a longer and healthier life. The science behind many of these products, however, is not always convincing to some public health scientists, or epidemiologists.
"What we know is that diets rich in fruits and vegetables appear to be much healthier, leading to less chronic disease and lower healthcare costs, but it's less clear how any specific dietary items affect longevity," says Hubert Warner, PhD, associate director of the biology of aging program at the National Institute of Aging.
Warner also says that not eating much food at all, ever, may promote living longer, while also making life decidedly less enjoyable.
"Many animal studies show that calorie restriction, meaning a permanent, low-calorie diet, can lengthen life in the laboratory," says Eugenia Wang, PhD, professor of biochemistry at the University of Kentucky in Louisville, who studies the genetics of aging. Several monkey studies on calorie restriction are under way at the University of Wisconsin, according to Warner, but no human studies have been done.
So if you're looking for foods for living longer, a plant-based diet -- something very similar to what most of us would consider a vegetarian diet -- seems to be the ticket, these experts say.
"There are thousands of small, short-term studies of foods or supplements that may show a particular effect, but when you look at large, long-term studies of how diet affects longevity and healthcare costs in the real world, it is plant-based diets that actually appear to be healthier," says Neal Barnard, MD, president of the Physicians' Committee for Responsible Medicine and author of Eat Right, Live Longer: Using the Natural Power of Foods to Age-Proof Your Body and other books.
Barnard cites a study, "Ten Years of Life. Is It a Matter of Choice?" as an example of this evidence. In the study, researchers looked at 34,192 non-Hispanic, white Seventh Day Adventists over age 30.
"Researchers like to study the Adventists because they are nearly all nonsmokers, they avoid alcohol, and are mostly vegetarians," says Barnard. Roughly 30% of the study subjects were vegetarians; about 20% were semi-vegetarians, eating meat less than once per week. The research showed that vegetarian men and women had "an expected age of death at 83.3 and 85.7 years, respectively." Men lived 7.28 years longer than the average American man, and women lived 4.42 years longer than the average American woman.
"This gives Adventists a higher life expectancy than any other formally described population," the study authors' wrote.
Ten extra years, without resorting to calorie restriction. What's more, this plant-based diet may offer protection from disease, according to the landmark China Project study, the largest study of diet and disease ever.
"In the '80s, China was like a huge living lab," says Banoo Parpia, PhD, an associate researcher at Cornell University in Ithaca, N.Y., who is involved with the China Project. "People didn't travel, and they ate locally." The thousands of people studied were largely without refrigeration or processed foods. They ate essentially a pre-modern diet, often growing their own food.
In more than 65 rural Chinese counties, researchers took blood and urine samples, weighed food, gave questionnaires, and filled out subject histories on everything from smoking history to age of onset of puberty.
Chinese diets were low in total fat (about 6% to 24%) and much higher in dietary fiber (about 10 to 77 grams per day). These diets contained less than 20% animal-based foods. The average American diet contains about 60% or more animal-based foods.
"At that time, China had higher rates of communicable diseases so their average life span was shorter than in the U.S., but the rate of heart disease and diabetes was very low, and breast cancer was almost nonexistent," says Parpia.
When the researchers correlated this information with the reported incidence of cancer for the areas, they were able to attribute the low levels of chronic disease and some cancers to the Chinese plant-based diet.
"The China Project study and others like it allow us to actually assess how diet affects incidence of disease and longevity in the real world," says Barnard. "What we see over and over again is that vegetarian or near-vegetarian diets over a lifetime yield a five- to 10-year lengthening of life."
Published April 29, 2003.