Definition: okinawa

Four times more centenarians:

For tourists, Okinawa is an archipelago of 161 green islands with pristine sand, bathed in the turquoise waters of the China Sea, between Japan and Taiwan. For historians, Okinawa evokes the greatest battle of the Pacific War. A litany of superlatives: beginning on 1 April 1945, it would mobilise more ships, more soldiers, use more bombs and, above all, claim more victims than any other operation in the Pacific: 50,000 among American soldiers, more than 107,000 among the Japanese, and 100,000 deaths among the civilians of Okinawa. But by occupying Okinawa from 1945 to 1972 and keeping detailed records of the inhabitants' health, the Americans were unaware that they were helping to shed light on another record. The inhabitants of this archipelago are not quite like us: they are three to four times less likely to develop cancer and other age-related degenerative diseases. Above all, with four times more centenarians than in France, Okinawa is the place where people live the longest on Earth! Three researchers recently uncovered the secret to the longevity of Okinawa's inhabitants: a geriatrician, Dr Makoto Suzuki (University of Okinawa, Japan) and brothers Bradley and Craig Willcox, one an internal medicine specialist and the other an anthropologist. Today, they are making recommendations for living as long as the inhabitants of this archipelago.

Longer in good health:

Makoto Suzuki was born in Yokohama, Japan, in 1933. In 1970, he was sent to the archipelago with the mission of setting up a clinic. "There were no doctors or hospitals," he recalls. "It was very intriguing." His investigation first took him to the village of Yomitan. "There were a great many elderly people living there. I met a centenarian who told me in the most natural way that another centenarian lived in the neighbourhood, also in good health." In Okinawa Prefecture, birth and death records have been kept up to date since 1872. Suzuki quickly identified 28 centenarians. "I went to visit them or called them. Of the 28, 24 lived at home, 24 were in good health, and 4 were in nursing homes. I was impressed. So, in 1976, I convinced the Ministry of Health to fund a study of these centenarians to understand what was happening in Okinawa." In the early 1980s, Dr Suzuki received help from two Canadian students, Bradley and Craig Willcox, who had come on a government scholarship. Together, they collected very detailed data on 675 centenarians. The Okinawa Centenarian Study was born. The oldest of its kind, it continuously tracks nearly 600 centenarians and four supercentenarians over the age of 110. Thanks to this study, we now know more about the environmental factors that lead to super-longevity. "An American has an average of seven years of disability at the end of their life, but an Okinawan has only two and a half years," notes Bradley Willcox. "Not only do Okinawans live longer, they live longer in good health."

Fewer calories:

In the early 1990s, studies conducted by Yukio Yamori (Kyoto University) established that Okinawans who emigrated to Brazil and abandoned their habits were struck by obesity and cardiovascular disease. Their life expectancy was reduced by 17 years compared to those who remained in their homeland. On the other hand, emigrants who continue to live as they did in the archipelago generally reach an advanced age. This led researchers to rule out the predominant influence of genes on longevity and to focus on lifestyle. "By analysing nutritional data," says Bradley Willcox, "we discovered that all the elderly people in Okinawa share a common dietary factor, one that ageing specialists have been studying for years, and which is the only factor capable of increasing life expectancy in all animal species: calorie restriction."

While an American consumes an average of 2,500 calories (kcal) per day and a French person 2,300, an Okinawan consumes only 1,800. Researchers believe that these 600 to 700 fewer calories per day are the secret to their extraordinary longevity. How can this be explained? The phenomenon can be summarised as follows: the more we eat, the more we age, and this is due to highly reactive particles called free radicals, which damage all the components of living organisms. Conversely, the low-calorie diet practised in Okinawa reduces the amount of free radicals, thereby sparing our organs. Life expectancy increases and the incidence of age-related diseases decreases. While free radicals normally increase with age, blood tests carried out on centenarians in Okinawa show that they have very low levels of free radicals: they suffer half as much damage as their younger counterparts in their seventies, whose dietary habits have become less healthy.

Eating means ageing:

Mitochondria, our cellular powerhouses, use food to produce 90% of the body's energy. But this process is not "clean". A small number of electrons stick to oxygen to form an extremely aggressive particle, a free radical called superoxide. By transforming food, we produce 2 kg of this free radical every year, which constantly damages our mitochondria. Over the years, these cells provide less and less energy (which explains why older people get out of breath) and more and more free radicals that attack the components of cells and organs. They are responsible for ageing and over a hundred diseases such as cancer, coronary heart disease and Alzheimer's.

Calorie restriction:

However, there is no sign of malnutrition among these centenarians. "On the contrary," says Bradley Willcox, "food and cooking play an important role in Okinawan culture." According to the researcher, the oldest inhabitants of Okinawa practise calorie restriction without deprivation. In fact – and this is one of the most surprising revelations of the Okinawa study – although the archipelago's centenarians have consumed fewer calories than Westerners throughout their lives, they actually eat more food than we do, if we take weight as the criterion! To take just one example, a cheeseburger weighs only 100 g but provides 280 calories. This is precisely the number of calories provided by a traditional Okinawan meal: fried vegetables, brown rice and soup, weighing a total of 500 g, or five times that of the hamburger.

And that is the key to this calorie restriction that does not leave you feeling hungry: foods with a low calorie density (relative to weight), which lead to satiety more quickly. They are also richer in vitamins and minerals. Thanks to these elements, the inhabitants of Okinawa can eat without depriving themselves, without gaining a gram and while slowing down the ageing process! In fact, during a meal, we are more sensitive to the weight of what we eat than to its calorie density. This was recently demonstrated by Barbara Rolls' team (University of Pennsylvania). She showed that women who are served a dish of pasta and vegetables invariably eat the same amount of food, regardless of whether it is more or less caloric. But here's the thing: most so-called "modern" foods – pizzas, hamburgers, soft drinks, potatoes, chips, white bread, chocolate bars – have a high calorie density. Processing wheat grain into white flour increases its calorie density sixfold. Yet more than 50% of the calories consumed by the French come from refined cereals and added sugars. To feel full after such meals, you inevitably have to consume more calories. And in the process, you accelerate the ageing process. Studies conducted on Okinawans who emigrated to Brazil show that they consume 18 times more meat than in the archipelago, twice as much charcuterie, three times more sugar and dairy products, and three times less vegetables and fish. This amounts to a total of more than 30% extra calories. And there are five times fewer centenarians among them than in Okinawa itself.

The Okinawa pyramid:

Those responsible for the centenarian study have just developed a series of dietary recommendations to slow down ageing, based on the Okinawa diet. These recommendations are presented in the form of pyramids. To understand their significance, we must first examine the official French guidelines (illustrated below by Didier Marandin for Sciences et Avenir).

For cultural and economic reasons, cereals and starchy foods form the basis of the diet. Dairy products also occupy an important place (3 to 4 per day), again for reasons that have more to do with economics and cultural habits than pure science. In contrast, the Okinawa diet (illustrated below by Didier Marandin)

consists of fruits, vegetables, seaweed, soups and soy products, which are both low in calories and filling. "You can eat these foods at will," says Bradley Willcox. "You'll never go hungry and you'll never gain weight." For more variety, Dr Willcox recommends making up three-quarters of your meal from this category and adding small amounts of the other foods shown in the pyramid. Sweet potatoes, which have a low glycaemic index, are preferable to our potatoes. Rice should be eaten whole. You can vary between lean fish and fatty fish rich in omega-3. Contrary to what is recommended by Western nutritionists, researchers in Okinawa advise eating less as you get older, following the example of Okinawa's centenarians, while maintaining regular physical activity.This is because as we age, our basal metabolic rate decreases: we burn fewer calories at rest, which increases the risk of becoming overweight.

When America tightens its belt:

The study of Okinawan centenarians is indirect evidence that calorie restriction (CR) increases life expectancy in humans, as it does in 50 animal species. But how can this be proven conclusively? A lifetime intervention study is obviously out of the question. However, the US National Institute on Ageing (NIA) believes it can get around this difficulty with a world first: two short-term calorie modulation studies in volunteers, which should demonstrate that human ageing is indeed modulated by what we eat.

The NIA has given the green light to human trials because, since 1987, it has become convinced that CR is beneficial in our closest cousins, monkeys. "If CR has comparable effects in humans and proves to be safe, it could contribute to healthy ageing," says Evan Hadley, who is supervising one of these studies, called CALERIE (Comprehensive Assessment of Long-term Effects of Restricted Intake of Energy). CALERIE will test the effects of a 20-30% reduction in calories in non-obese volunteers over a period of two to three years. "We want to know," he says, "if such a restriction is feasible, and measure its influence on disease risk and on the markers of longevity that we have identified in observational studies." Among these markers that predict life expectancy are DHEA (dehydroepiandrosterone) and albumin levels.

A study on fasting:

Another NIA study is looking at the consequences of fasting. Supervised by Mark Mattson, head of the NIA unit in Baltimore, it will follow twenty volunteers from September 2004 who will be asked to eat either three meals a day, which will not change their habits much, or a single meal in the evening, with the number of calories consumed remaining the same for both groups. This is therefore not a true calorie restriction, but rather a simulation of intermittent fasting. "This study is based on work we have conducted in rats and mice," says Mark Mattson. "We noticed that rats that only eat every other day show the same benefits as those that are calorie-restricted. However, these rats do not eat less, as they make up for it on the day they are fed. But their blood sugar levels are better and their brains age less. We are betting that the same phenomena will be found in our volunteers." Fasting these men and women every other day was too stressful, so the study was adapted accordingly. At the end of the six-month experiment, these volunteers will undergo a battery of blood tests and psychometric tests.

These prototype studies in humans are intended to be expanded. "If we obtain significant results," says Mark Mattson, "the NIA will probably issue dietary recommendations for the entire population." One of the world's leading experts in the biology of ageing, he wasted no time in applying them himself. The semi-calorie-restricted diet that Dr Mattson has been following for several years would make any "traditional" nutritionist's hair stand on end. "I don't eat more than 2,000 calories (kcal) a day," he explains. "I never eat breakfast." Dr Mattson suspects that the total number of calories consumed is probably more important than their distribution between fats, proteins and carbohydrates. And that it is better to eat only once a day. "People who eat only one meal feel hungry during the first few weeks. After that, they feel incredibly well and full of energy." If the ongoing studies prove him right, he has found a way to radically simplify all the nutritional advice for living a long and healthy life!

70 years of calorie restriction:

In 1935, Clive McCay, a veterinarian at Cornell University in New York State, published an article that would revolutionise our understanding of ageing. McCay recounts how he found a way to extend the life of his rats. To achieve this, the researcher put them on a diet, taking care to enrich their food with vitamins and minerals. Since then, calorie restriction has produced the same results in nearly 50 species, from rodents to invertebrates to fish. When their calorie intake is reduced by 30 to 40%, these animals live 20 to 40% longer than their counterparts who feed freely. They are also functionally younger. Low-calorie diets increase both average life expectancy (more animals live longer than the usual average) and maximum longevity (the maximum lifespan of the species).