The Okinawa Centenarian Study : Evidence based gerontology

Prevalence of dimensia is significantly lower in Okinawa than USA

Prevalence surveys suggest that the dementia rate is fairly low among the Okinawan elderly, compared to other elderly populations. Even into their late 90s Okinawans suffered lower dementia rates than reported for comparable populations in the United States and elsewhere.

7. Lean and Fit Elderly

In Okinawa, every city, town, and village has a family register system (koseki) that has been recording reliable birth, marriage, and death statistics since 1879. Life tables calculated from this database show one of the world's highest concentrations of centenarians and likely the world's longest life expectancy for any country or state.

A Selection of Findings
After examining over six hundred Okinawan centenarians and numerous "youngsters" in their seventies, eighties, and nineties, we saw certain patterns begin to emerge. It became clear that the Okinawan lifestyle was providing some real, scientifically verifiable reasons these people were so incredibly healthy so far into their senior years. And they were reasons that could have a profound impact on our health and well-being here in the West. Let's take a look at some key findings and what they mean in terms of health and successful aging-for the Okinawans, and ourselves.

1. Successful Aging is More Than Just Good Genes

Genetic studies of Okinawan centenarians have shown that while there is some genetic protection that helps the Okinawans live to extreme ages most of the "successful aging" phenomenon is due to lifestyle. For example, Okinawan centenarians have HLA (human leukocyte antigen) genetic patterns that place them at lower risk for autoimmune diseases but even some of those with the higher risk HLA patterns lived to the century mark indicating lifestyle may be as important as genetics in living to one hundred. Other genetic factors such as specific gene polymorphisms associated with long-lived families and individuals are currently under study. While genetic studies are extremely important demographic studies of Okinawans and other Japanese have shown that Okinawans have gained over twenty years in life expectancy over the last four decades mostly due to reductions in stroke and stomach cancer mortality-clear evidence that lifestyle intervention has been the key factor in this longevity phenomenon.In addition, migration studies show that Okinawans who grow up in other countries and abandon their protective lifestyle patterns suffer from higher all-cause mortality rates (especially cardiovascular disease) than those who grow up in Okinawa (see Mizushima S, et al. Hypertens Res. 1992;15:45-55).

2. Reduced Free Radical Damage
One of the most important findings in free-radical research has been that eating fewer calories increases life span (see Sohal RS, et al. Science 1996;273:59-63). The only evidence that this works in humans has been indirect and based on observation of the low caloric intake of the Okinawans and their long life expectancy (see Weindruch, R., et al. N Engl J Med 1997;337(14):986-94). Now we have direct evidence that the Okinawans following the traditional ways have low blood levels of free radicals. The elders had significantly lower levels of lipid peroxide-compelling evidence that they suffer less free-radical-induced damage.

Levels of Lipid Peroxides in Okinawan Centenarians and Septuagenarians
	Male		Female		Total
	100 yo	70 yo	100 yo	70 yo	100 yo	70 yo
Number of Cases	30	11	109	18	139	29
Lipid Peroxides	1.49±0.51*	3.15±0.70	1.72±1.28*	3.56±0.81	1.67±1.16*	3.40±0.79
*p <0.05

3. Low Cardiovascular Risk
Elderly Okinawans were found to have impressively young, clean arteries, low cholesterol, and low homocysteine levels when compared to Westerners. These factors help reduce their risk for coronary heart disease by up to 80% and keep stroke levels low. Their healthy arteries are mostly due to their lifestyle; diet, regular exercise, moderate alcohol use, avoidance of smoking, blood pressure control, and a stress-minimizing psychospiritual outlook.

The chart on right indicates that the higher the plasma homocysteine (a new risk factor) level is, the more people suffer from cardiovascular disease. Homocysteine is an amino acid that causes damage to arterial walls. It is higher in people who don't get enough folate (e.g. green leafy vegetables) and vitamins B6, B12.

4. Low Risk for Hormone-Dependent Cancers
Okinawans are at extremely low risk for hormone-dependent cancers including cancers of the breast, prostate, ovaries, and colon. Compared to North Americans, they have 80% less breast cancer and prostate cancer, and less than half the ovarian and colon cancers. Some of the most important factors that may protect against those cancers include low caloric intake, high vegetables/fruits consumption, higher intake of good fats (omega-3, mono-unsaturated fat), high fiber diet, high flavonoid intake, low body fat level, and high level of physical activity.

Hormone-Dependent Cancer Risk Yearly Cancer Deaths (per 100,000 people)
Location	Life Expectancy	Breast	Ovarian	Prostate	Colon
Okinawa	81.2	6	3	4	8
Japan	79.9	11	3	8	16
Hong Kong	79.1	11	3	4	11
Sweden	79.0	34	10	52	19
Italy	78.3	37	4	23	17
Greece	78.1	29	3	20	13
USA	76.8	33	7	28	19

Adapted from World Health Organization 1996; Japan Ministry of Health and Welfare 1996

5. Strong Bones



	evidence. The most important evidence needed for any centenarian study is reliable age-verification data.
Evidence-Based Gerontology One of the most important things about the Okinawa Centenarian Study is the fact that it is based on solid
		Nakajimasan, a typical healthy centenarian was reported to be in particularly good health, completely independent, and still farming. He is shown here getting his bone density tested by heel bone ultrasound.

Okinawans have about 20% fewer hip fractures than do mainland Japanese, and Japanese have about 40% fewer hip fractures than Americans (see Ross PD, et al. Am J Epidemiol 1991;133:801-9). Our research on Okinawan elders showed that their bone density, when adjusted for body size, is similar to Americans, and like the rest of us they continue to lose bone mass as they get older, but possibly at a slower rate. We compared bone mineral density in a group of Okinawans to two groups from mainland Japan and found that by age forty for women and age fifty for men the groups began to diverge. The Japanese began to lose significantly more calcium from their bones than the Okinawans, suggesting the Okinawans preserve their bone density at healthy levels for longer periods of time than other Japanese (see Suzuki M, et al. Japanese J Bone Res 1995;63:166-72 [in Japanese]). Protective factors that may play a role here include high calcium intake by Okinawans in both food and their natural drinking water, high vitamin D levels from exposure to sunlight, increased physical activity, especially at older ages, and high intake of dietary flavonoids (estrogenic compounds from plant foods).

6. Low Prevalence of Dementia

Photo: 97 year old karate master Seikichi Uehara

Okinawan elders are lean, with average body mass index (BMI) that ranges from 18 to 22 (lean is less than 23). The Okinawans stay lean by eating a low-calorie, unrefined-complex carbohydrate diet, practicing calorie control in a cultural habit known as hara hachi bu (only eating until they are 80% full), and keeping physically active the natural way. In contrast, middle-aged Okinawans (age 50) who have a less traditional lifestyle have a BMI of 26, the highest in Japan and similar to Americans. A BMI greater than 25 is considered overweight and places you at greater risk for chronic diseases, especially cardiovascular disease (heart disease and stroke).

8. Natural Menopause

There are virtually no women in Okinawa using estrogen replacement therapy. They experience menopause naturally and nonpharmacologically with fewer complications such as hot flashes, hip fractures, or coronary heart disease. Lifestyle determinants include diet, avoidance of smoking and exercise in the form of dance, soft martial arts, walking and gardening. Okinawan women have a very high intake of natural estrogens through their diet, mainly from the large quantities of soy they consume. Soy contains phytoestrogens, or plant estrogens called flavonoids. The other important major phytoestrogens are lignans, which are derived from flax and other grains. All plants, especially legumes (beans, peas), onions, and broccoli, contain these natural estrogens, but not nearly in the same quantity as soy and flax. Recent double-blind placebo controlled studies support the ability of soy isoflavones to slow the bone loss (see Alekel D, et al. Am J Clin Nutr 2001;72:844-52) and hot flashes (see Albertazzi P, et al. Obstet Gynecol 1998;91:6-11) that occur with menopause.

9. Youthful Sex Hormones

Okinawan elders may have higher levels of sex hormones, including natural DHEA, estrogen, and testosterone than similarly aged Americans, suggesting that the Okinawans are physiologically younger. DHEA is a steroid produced in the human adrenal gland, and some studies suggest that it may help ameliorate the ravages of aging. However, taking DHEA supplements could increase risk for breast and other cancers so we do not recommend taking DHEA supplements. More supported by the scientific literature is that DHEA levels decline in direct ratio with age, so it may be a good marker of biological age. Okinawans seem to have higher DHEA levels than similarly aged Americans suggesting that Okinawans may age slower than Americans. As Okinawans age, both sexes maintain remarkably higher levels of estrogen which may help protect against heart disease and osteoporosis. Testosterone is the male equivalent of estrogen. Higher endogenous levels increase our muscle mass and our body hair, deepen our voices, and control our libidos, among other functions. This hormone also appears higher in older Okinawan men. Cross-cultural population studies are needed to confirm these differences and their biological significance.

Sex Hormones in Okinawans and Americans
Age Group (years)	DHEA (ng/mL)	Testosterone (ng/dL)	Estrogen (pg/mL)
Okinawan men 70 y	2.6	439	35.7
American men 70 y	2.0	314	20.6
Okinawan men 100 y	0.8	298	12.1

Okinawan women 70 y	3.0	13	15.5
American women 70 y	1.1	17	5.5
Okinawan women 100 y	0.6	39	4.2

Normal ranges for these age groups	M 0.5-5.5 F 0.3-4.5	M 240-950 F 20-80	M 0-50 F 0-35

Source: Suzuki M., et al. Centenarians in Japan. Tokyo, Japan:Nakayamashoten 1995:64-78.

10. Excellent Psychospiritual Health
Personality testing found that centenarians, when in their prime of life, scored low when it came to feelings of "time urgency" and "tension" and high in "self-confidence" and "unyieldingness." Interviews revealed optimistic attitudes, adaptability, and an easy-going approach to life. Moderation was found to be a key cultural value. Strong social integration and a deep spirituality were particularly evident among older women (see Willcox DC, et al. Geriatr Med 2000;38:2000-9 [in Japanese]).

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11. Integrative Health Care
The Okinawans incorporate both Eastern and Western healing methods into their health care system. Okinawa, Japan, and Hong Kong are the top three areas of the world in life expectancy, and what is interesting in their health care systems is that they have all incorporated both Eastern and Western approaches to healing. The use of natural or herbal tonics in these populations far exceeds that of North America. The implications of this type of health care are currently under investigation.

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