Scientific research

Scientific research

Since the 1950s, a large body of scientific research has found that people who follow traditional Mediterranean and Asian dietary and lifestyle practices are healthier and live longer than any other people in the world. The selection of studies below highlight the health-giving benefits of traditional Mediterranean and Asian dietary and lifestyle practices.

The Lyon Diet Heart Study

In 1988 Michel de Lorgeril, M.D., from the University of Saint-Etienne in France, teamed up with researchers from the French National Center for Health Research to investigate the protective effects of a Mediterranean diet. In what became known as the Lyon Diet Heart Study, researchers randomly divided 605 male and female heart attack survivors into two groups. One group was advised to eat the standard "prudent" low-fat diet suggested for heart patients. The other half were advised to eat a Mediterranean-style diet, complete with plenty of vegetables, fruits, grains, beans and olive oil, small amounts of red meat, moderate amounts of fish and poultry, and wine with meals. Instead of butter they were advised to use a canola oil-based spread.

Although the study was originally scheduled to last for five years, after only two years researchers were so astounded by the differences in the two groups that the study was abruptly ended for ethical reasons. It was found that those following the Mediterranean-style diet had a 70 percent lower death rate compared to those following the prudent low-fat diet. In a follow-up report the researchers also discovered that cancer rates among the Mediterranean group were 61 percent lower than those of the other group.

"The results were spectacular and of unexpected magnitude," reported Serge Renaud, Ph.D. from the French National Center for Health Research, Bordeaux, who helped initiate the study. "The protective effects of the diet began to occur within two months of observation."

In fact, the results of the Lyon Diet Heart Study — results that hadn't been seen in any other diet, drug or medical procedure — were deemed so important that they were published in three prestigious medical journals, the American Journal of Clinical Nutrition, the Lancet and the Journal of the American College of Cardiology.

The Seven Countries Study

In 1958 professor Ancel Keys, director of the Laboratory of Physiological Hygiene at the University of Minnesota School of Public Health, launched the Seven Countries Study. For more than a decade Professor Keys, with the help of an international team of specialists, studied the diet, lifestyle and incidence of coronary heart disease among 12,763 randomly selected middle-aged men from seven countries: the United States, Japan, Italy, Greece, the Netherlands, Finland and Yugoslavia.

When all the research was analyzed, a clear and predictable pattern emerged. In the Mediterranean and Asian regions of the world (Greece, Japan and southern Italy) — where vegetables, grains, fruits, beans and fish took center stage—heart disease was found to be rare. But in those countries where people filled their plates with red meat, cheese and other foods high in saturated fat — such as in the United States and Finland—the rates of heart disease were found to be very high.

Professor Keys' research convinced him that diet played the primary role in the onset of coronary heart disease. But, after so many years of research, he had come to realize that food may not be the only factor involved. Professor Keys also observed that Mediterranean and Asian peoples were physically active, family ties were strong, and the pace of life was leisurely. Keys concluded that although diet was the single most important factor, it was a combination of dietary and lifestyle factors that were responsible for the remarkably low rates of heart disease in Mediterranean and Asian regions.

One of the surprising findings of the Seven Countries Study was that people living on the Greek island of Crete consumed up to 40 percent of their calories from fat, yet they had the lowest rate of heart disease and the highest average life expectancy in the world (along with Japan). However, Professor Keys found that unlike the saturated fat that was prevalent in American and Finnish diets, the majority of the fat in the Cretan diet came from olive oil and fish which are rich in unsaturated fats. Keys concluded that although saturated fat can be harmful to your health, unsaturated fats can have positive health benefits.

The China-Cornell-Oxford Project (China Study)

The China-Cornell-Oxford Project (also known as the China Study), conducted by Cornell University in the United States, Oxford University in England, and the Chinese Academy of Preventative Medicine, was launched in 1983. The study, which focused on China, was massive in it's proportions. Dozens of researchers were involved, led by T. Colin Campbell, Ph.D., professor of nutritional biochemistry at Cornell University. Between 1983 and 1990 researchers traveled across the far reaches of China—from the southern coastal regions to the Gobi desert—studying the dietary practices and disease rates among 10,200 Chinese men and women.

To make the study as comprehensive and thorough as possible, Dr. Campbell and his colleagues collected every conceivable piece of information they could about their subjects. They found that a rural Chinese diet was the same diet that had been eaten in China for thousands of years. It was rich in plant-based foods such as rice and vegetables, low in animal foods and contained around three times more fiber than an average Western diet. The rates of heart disease and breast cancer in these areas was also found to be many times lower than in Western society, as was prostate cancer and osteoporosis. Obesity was also very rare.

But when further research was conducted on Chinese populations living outside of rural areas, it was a different story. It was found that the diet in many urban areas of China was a lot more Westernized — with far more animal food consumption at the expense of traditional dietary staples like rice and vegetables.

It was also found that the urban Chinese who had abandoned their traditional diet had much higher rates of common Western ailments than their rural cousins—including heart disease, breast cancer and prostate cancer. And obesity, which was rarely seen in rural Chinese populations, was found to be common among those Chinese eating a Westernized diet.

When the years of painstaking research were completed in 1990, The China Study had generated the largest database in the world on the multiple causes of disease. And the findings of the study were clear: "In the final analysis," reported Dr. Campbell, "we have strong evidence from this and other studies that nutrition becomes the controlling factor in the development of chronic degenerative diseases."

The China Study was hailed as a great success. Dr. Mark Hegsted, professor emeritus of nutrition at Harvard School of Public Health called it "a very, very important study—unique and well done." The New York Times dubbed it the "Grand Prix of epidemiology," and went on to describe it as "the most comprehensive large study ever undertaken of the relationship between diet and the risk of developing disease . . . tantalizing findings."

The GISSI-Prevenzione Study

The positive results of the Lyon Diet Heart Study were duplicated recently by the GISSI-Prevenzione Study, a large-scale clinical trial organized by the Italian National Association of Hospital Cardiologists which evaluated the long-term changes in dietary habits of a group of Italian heart attack survivors.

Study participants were divided into five categories according to how much of their diet consisted of vegetables, fruit, fish, olive oil and butter. The number of patient deaths in each category was noted over the duration of the study.

Compared to those who most followed traditional dietary practices, those who consumed the most butter had a 2.6 times greater risk of dying within 42 months after their heart attack. "A significantly lower risk of death was associated with eating more Mediterranean-style foods and fewer foods containing saturated fats, such as butter," reported Roberto Marchioli M.D., who helped co-ordinate the study.

Asian Diet and Breast Cancer

Researchers from the University of California recruited 25 breast cancer survivors to determine the merits of an Asian-style diet in reducing the risk of breast cancer re-occurrence. The study participants were placed on an Asian-style diet rich in vegetables and grains, low in red meat and saturated fat but rich in omega-3 fat from fish oil, and their progress was noted.

During the three-month study there was no re-occurrence of breast cancer in any of the subjects and the researchers also found that the breast fat composition of the women had bio-chemically changed in response to the diet. In fact, levels of healthy omega-3 in the breast had increased by 40 percent. "My colleagues and I have shown that at least one aspect of human breast composition in American women can be altered to approximate the breast composition of women in certain Asian and European countries…in those countries, the incidence of breast cancer is much lower than it is here," reported John Glaspy, M.D., director of the University of California Oncology Center and lead author of the study. Dr. Glaspy was also surprised at how fast the healthy changes in the breast had occurred: "I think it shows that not only are you what you eat, you are what you ate very recently."

The researchers also noted that the Asian-style diet promoted better cardiovascular health as well as weight loss.

Mediterranean Diet and Weight Loss

A Mediterranean-style diet can help you lose weight and maintain that loss according to a study by researchers at Brigham and Women's Hospital and Harvard Medical School.

In the study 61 overweight men and women consumed one of two diets: a standard low-fat diet or a Mediterranean-style diet with regular moderate consumption of healthy monounsaturated fat from olive oil, olives, nuts and nut products (such as nut oils and peanut butter). Both groups were instructed to consume the same number of calories.

After six months both groups had experienced roughly the same amount of weight loss, but the big difference came at the end of the study, 12 months later. It was found that a large number of the Mediterranean diet group had stuck with the diet and maintained their weight loss. However, many of those on the low-fat diet couldn't stick with it and had not only regained their lost weight, but weighed more than they did before the study began. "In our study, three times as many people trying to lose weight were able to stick to a Mediterranean-style diet versus the low-fat diet," reported lead author of the study Kathy McManus, R.D., director of nutrition at Brigham and Women's Hospital. She noted that "Patients loved this diet because they could include favorite foods if they carefully watched portion sizes."

The researchers concluded that "Motivation and adherence are very hard to sustain in any weight loss programs, but the results from this study suggest that the tastier the food, the greater overall success of the diet plan—even if it does include moderate amounts of fat."

The Ni-Hon-San Study

The Ni-Hon-San Study was initiated in the 1960s to evaluate dietary and lifestyle differences between middle-aged Japanese men living in Japan, Hawaii and San Francisco, and how this influenced their risk of cardiovascular disease and mortality.

After five years, the study found that the Japanese men living in Japan (who generally followed traditional Japanese dietary and lifestyle practices) had low blood cholesterol levels and very low rates of heart disease. However, it was found that the partly-Westernized Japanese men living in Hawaii had higher blood cholesterol levels and almost twice the rate of heart disease, while the fully-Westernized Japanese men living in San Francisco had the highest blood cholesterol levels and almost triple the rate of heart disease compared to the Japanese men living in Japan.

Because there were no genetic differences between the study participants, the researchers concluded that migration and the adoption of Western dietary and lifestyle practices were the main reasons behind the differences in blood cholesterol and heart disease rates.

Mediterranean Diet and Survival of the Elderly

A six-year study conducted by an international team of researchers found that people who live in Greece and consume a traditional Mediterranean-style diet have much lower mortality rates than Greeks who have adopted Western dietary practices.

The study involved 182 elderly Greek men and women, who were first surveyed about their eating habits, using an extensive validated questionnaire, between 1988 and 1990. During the follow-up in 1993-94 it was found that 53 of the people originally surveyed had died. The researchers then compared the eating habits of the subjects who had died to those still living.

To aid in their analysis they broke down the traditional Greek diet into eight separate components including low consumption of red meat, high consumption of grains, moderate consumption of wine and high consumption of vegetables. Each component was assigned a "diet score."

The researchers found that the more closely a person followed a tradtional Greek diet, the less likely they were to die. For each traditional dietary component included in a person's diet, the risk of death dropped by 17 percent. Most of the people who died during the 6-year study tended to have lower diet scores—they ate more red meat, less olive oil and fewer vegetables, grains and fruits than those who lived the study showed.

"We knew fruits and vegetables helped stave off cancer and heart disease, and that modest amounts of wine are cardio-protective," reported study author Dr. Dimitrios Trichopoulos from Harvard School of Public Health,"now we know that the overall dietary pattern—rather than individual components—is important for health and longevity." He also pointed out that "It's a diet you can easily introduce or use even in the American diet because it does not require sacrifice. You do not have to cut down on fat."

Mediterranean Diet Advantages in Other Populations

The researchers involved in the Greek dietary practices study (above) conducted a similar study in Melbourne, Australia. This time they looked at the dietary practices of two groups of men and women, 189 Greek-Australians and 141 Anglo-Celtic Australians.

The results mirrored those of their original Greek study. For each traditional Mediterranean dietary component included in a person's diet, the risk of death dropped by 17 percent. This was the case for both the Greek-Australian group and the Anglo-Celtic Australian group. The authors of the study concluded that a diet that adheres to the principles of the traditional Mediterranean diet is associated with longer survival among people of either Greek or Anglo-Celtic origin.

The Okinawa Centenarian Study

People who live on the Japanese island of Okinawa enjoy the longest life-expectancy in the world. Their rates of obesity, heart disease, osteoporosis, dementia and breast, colon and prostate cancer are also far lower than the rates of these illnesses in industrialized Western countries like the United States, Australia and Britain. The 25-year Okinawa Centenarian Study investigated why Okinawans enjoy such exceptional health.

After examining over six hundred Okinawan centenarians (people who live to 100 or more) and numerous other elderly Okinawans, it became clear to researchers that their robust good health was mainly due to their traditional dietary and lifestyle practices.

It was found that the traditional Okinawan diet contained high amounts of sweet potato and other vegetables, rice, fruit and legumes (particularly soybeans), moderate alcohol intake, very little red meat but at least 3 servings a week of fish (particularly salmon, tuna and mackerel which are all rich in healthy omega-3s).

Researchers also noted that elderly Okinawans included regular moderate physical activity in their daily lives—such as practicing Tai Chi, cycling or walking to see friends. And interviews revealed that elderly Okinawans had strong social bonds and an optimistic and easy-going approach to life.

However, researchers discovered that many younger Okinawans had adopted a more Westernized diet and lifestyle, and not only weighed more but had higher rates of heart disease and cancer than elderly traditional-living Okinawans. They noted that this correlated with a study of Okinawans whose life-expectancy had dropped by 17 years when they had migrated to Brazil and abandoned their traditional ways.

The researchers concluded that traditional Okinawan dietary and lifestyle practices have the potential to make a profound difference to the health and wellbeing of anyone who decides to adopt them.

Mediterranean Diet and Arthritis

A study published in Annals of the Rheumatic Diseases found that a group of arthritis sufferers from Sweden who followed a Mediterranean-style diet for three months improved their arthritic symptoms and lost weight.

The study involved 51 rheumatoid arthritis sufferers who were divided into two groups. One group followed a Mediterranean-style diet (which included lots of vegetables, grains, fruits, legumes, regular servings of fish but little red meat, wine in moderation and olive oil as the main source of fat) while the other group, who were used as controls, did not change their eating habits.

After three months, those on the Mediterranean-style diet had experienced a number of improvements not seen in the control group, including a decrease in pain, inflammation, disease activity and the number of swollen joints. The Mediterranean diet group had also lost an average of nearly seven pounds and had lower cholesterol levels.

"The treated group felt significantly improved compared to the controls after three months with this diet," reported the lead author of the study Dr. Lars Skoldstam. He also noted that "the Mediterranean diet is palatable and should be easy for most patients to accept, even lifelong."