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Sci Tech
SPEAKING OF SCIENCE
How to live up to a healthy ninety
Seven years ago, it was estimated by researchers studying human ageing that there were about 100,000 men in the world who were over 100 years old. This works out to one in every 100,000 men in the world to be a centenarian, thus bringing new meaning to the Hindi phrase laakhon mein ek or the Tamil lakshathil oruvar.
The Book of Genesis states that Methuselah lived for a ripe 969 years. The Purana talks about how the great Shivabhakta Markandeya lives forever as a 16-year-old, having escaped the noose of Yama permanently. And the tiny Italian island Sardinia boasts of the largest number of centenarian men anywhere. What is the magic?
Lifestyle and habits
It does not seem to be due to any special longevity genes. Analysis of identical twins by Dr. James Vaupel of the Max Planck Institute for Demography suggests that genetic determinants account for about 25 per cent of variation in life span, leaving the rest 75 per cent to lifestyle and habits. This gives us the hope that if we suitably modify our lifestyle, we too can live longer and healthier.
It is here that the recent analysis of over 2,300 physicians in America is of interest. These form a voluntary group of over 22,000 doctors, assembled over 20 years ago, on whom extensive health and lifestyle records have been maintained on a regular basis.
Annual questionnaires
A research group at Boston, led by Dr. Laurel Yates, has analysed the data obtained by self-reports and annual questionnaires, on these 2,300 participants of the Physicians Health Study (PHS, 1981-2006), each participant over 90 years old, and in good health.
This study identifies five major risk factors, which go to reduce life span. These are: (a) sedentary life with no exercise, (b) hypertension or high blood pressure, (c) overweight, defined as body mass index greater than 25 (body mass index is calculated as the body weight in kg divided by the square of the height in metres), (d) smoking, and (e) diabetes, or higher than normal levels of glucose in the blood.
Each of these risk factors, as can be noticed, can be controlled and is thus a modifiable factor of life style.
Yates and associates found in their study that smoking alone reduces the chances of living up to 90 by 75 per cent. It is thus the greatest life-threatening factor. You have only 25 per cent chance of long life if you continue smoking. Next is obesity. Being fat, and staying fat, cuts down the possibility to 32 per cent. Diabetes cuts it down to 28 per cent, sedentary life to 44 per cent and hypertension cuts it down to 42 per cent.
An obese diabetic who smokes has three of these risk factors together, and has only 14 per cent chance of long life. And one with all five risk factors operating has but 4 per cent chance. (Winston Churchill, the sedentary, obese, and likely diabetic, smoker who died at 91, won this 4 per cent lottery.
On his 80th birthday, a reporter asked him if he could be interviewed on his 90th. Churchill looked at the reporter and said: “I do not see why not, you look healthy enough.”)
The Boston group does not seem to have asked the volunteers their food habits: whether they are vegetarians, or ate fish, white or red meat, and whether they ate full stomach or sparingly.
Modest drinkers
The answers would have been of interest, particularly for us in India. But, for someone like me who likes a tipple, they found that most of these doctors are modest drinkers. A bit of alcohol does not make any difference. Indeed, the Sardinian centenarians all drink red wine daily.
Dr. Ian Sample, who covered this study in a recent issue of The Guardian (reprinted in The Hindu), highlights it thus: what matters with these 90-year-olds is how well they took care of themselves from their 70s onwards.
They key to longevity may thus lie in keeping fit after 70. Life expectancy does not seem to be determined by their former life style.
Herein is a ray of hope for people like me. Forget about bad habits and risky life style of past years. Repent, reform and redesign your life.
Quit smoking, control blood pressure, exercise daily, trim your weight and BMI to a good 22, and cut down sugar in your food and drinks — and you can at least live up to 90.
Dr James Watson (of DNA fame) once told me that children are indestructible. He meant that if a child survives up to 4- 5 years, its immunity and physiological resilience is strong enough to take it up to 70 (the average human life span today). Yates and associates say that you can go beyond, up to 90.
Immune system
And work on the Sardinians suggests that in certain individuals the immune system of the body adapts to ageing. While its sophisticated machinery, the T and B cells, decline with age, the macrophages that offer innate immunity (which gobble up foreign cells and proteins) seem to get better after the age of 60-70.
Dr. Franceschi, who has done this work, says: “those who live longer are able to continuously adapt to the deteriorative changes occurring in the immune system with age.”
A few points of note. The Boston study has talked about exceptional longevity of men. What about women?
For reasons yet to be completely understood, women live longer than men. It would be of interest if a Yates-type study is conducted on the lifestyle of women beyond their sixties and seventies.
The other point is the value of planning and sustaining programmes such as the U.S. Physicians Health Study in other countries, especially in India.
The newly started Public Health Foundation of India, and its planned Institutes of Public Health, would be ideal places to start such a programme here. And while at it, it would also be valuable to start and maintain a twins registry in India. Such a registry would help tell apart genetic factors from environmental and life style factors, in the nature-nurture dialectic.
The final take home lesson is for senior citizens. Let us not think of the past. If we work towards winning over the five major risk factors by changing habits and behaviour, we can live longer and healthier lives.
Forget about Lalaata Likhita Rekha or Talai Ezhuthu (what is supposedly writ on my head, or destiny), we can change our health and quality of life — a case of feat challenging fate.
D. BALASUBRAMANIAN
dbala@lvpei.org
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