Scientists have homed in on the secrets of a longer life by studying thousands of pensioners who lived to their 90s and beyond. In the case of men, their chances of reaching their 90s were surprisingly dependent on how well they looked after themselves from their 70s onwards, the scientists found, suggesting their life expectancy was not already determined by their former lifestyle.
Detailed lifestyle records of the elderly volunteers revealed that men had to keep themselves in peak condition to have a reasonable chance of joining the nonagenarians, while women coped better and lived longer despite chronic and often disabling illnesses. Previous studies of twins suggest that about a quarter of the variation in human lifespan is governed by genes, leaving 75% that is influenced by our environment, diet and lifestyle.
Health experts have long known that lack of exercise, poor diet, smoking and stress can have a dramatic impact on lifespan, but have been less clear how big an effect each can have.
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Dr Laurel Yates, at the Brigham and Women's hospital in Boston, Massachusetts, studied 2,357 former physicians who volunteered at an average age of 72 in the early 1980s. At the beginning of the study, the men gave their height, weight, blood pressure, cholesterol and details of any exercise they did. Toward the end of the study, in 2006, they were questioned again, about any changes in their habits and health. A total of 970 men, or 41%, lived to 90 or older. From the details they gave, the scientists were able to work out how much different habits and lifestyle factors affected their lifespan.
Yates estimates that a 70-year-old man has a 54% chance of reaching the age of 90 if he does not smoke or have diabetes, has healthy weight and blood pressure, and exercises. But cutting out exercise and becoming more sedentary reduces the chances of reaching 90 to 44%. The chances dropped further with high blood pressure (36%), obesity (26%) and smoking (22%). Any three of these cut the chances of living to 90 to 14%.
"Smoking, diabetes, obesity and hypertension significantly reduced the likelihood of a 90-year lifespan, while regular exercise substantially improved it," Yates said. Most of the volunteers were modest drinkers. The study appears in the journal Archives of Internal Medicine. According to CIA World Factbook estimates, life expectancy last year ranged from 80.6 years for men and 86.2 for women in Andorra, to 31.8 years for men and 32.6 years for women in Swaziland. In Britain, the male lifespan averaged 76.2 years last year, with women living an average of 81.3 years.
In a second study in the same journal, Dellara Terry at Boston University gathered lifestyle details for 523 women and 216 men aged 97 and older. She found they split into two groups, those who dodged medical problems until after 85, and those who survived despite developing conditions such as heart disease, osteoporosis, high blood pressure and dementia. Though very few men reached the age of 100, those who did were mostly in the first group, and had good physical and mental health. More women coped with diseases without succumbing to them.