Smoking and obesity 'age people' 

http://news.bbc.co.uk/1/hi/health/4086900.stm
June 14, 2005

Being overweight and a smoker makes a person biologically 
older than slim non-smokers of the same birth age, UK and 
US researchers have found. Smoking accelerated the ageing 
of key pieces of a person's DNA by about 4.6 years. 
For obesity it was nine years. 

These genetic codes are important for regulating cell division 
and have been linked to age-related diseases. 

The study in the Lancet was based on 1,122 twins from a 
database held by St Thomas' Hospital in London. 

The researchers looked at telomeres - strips of DNA that 
cap the end of chromosomes and appear to protect and 
stabilise them. 

Telomeres shorten each time a cell divides, until there is 
nothing left, making cell division less reliable and increasing 
the risk of disorders. This happens naturally with ageing. 

Accelerated ageing 

Both smoking and obesity are important risk factors for 
many age-related diseases, therefore Professor Tim Spector 
and colleagues set out to see whether they might accelerate 
telomere shortening. 

Among the study sample, all women aged 18-76, 119 were 
clinically obese, 203 were current smokers and 369 were 
ex-smokers. 

By analysing blood samples for DNA the researchers found 
telomere length decreased steadily with age, as expected. 

However, the telomeres of the obese women and smokers 
were far shorter than those of lean women and those who 
had never smoked of the same age. 

Each pack year - the number of cigarette packs smoked 
per day multiplied by the number of years smoking - was 
equivalent to a loss of an additional 18% on top of the 
average annual shortening of telomeres. 

A woman who had smoked a pack per day for 40 years 
accelerated her ageing by 7.4 years, according to telomere 
length. 

Chromosomal clock 

Professor Spector, from the twin research unit at St Thomas' 
Hospital, said: "What you are seeing here is that the entire 
body is ageing from smoking, not just your heart or your lungs. 

"So you are accelerating your whole chromosomal clock by 
this activity which is an important message for younger 
people to think about. 

"People would probably think twice if they knew that at every 
age they were five or seven years older than their contemporaries 
biologically because that has influences on their skin, brain and 
bones." 

Tobacco smoke contains poisons. The research suggests that 
these poisons may affect cells at one of the most fundamental levels. 

Excess fat is believed to disrupt the chemical proposition of the 
body in a negative way. 

Such stressors can damage the body. 

Dr Lorna Layward, research manager at Help the Aged, said 
the work supported what we already know about smoking and 
obesity being extremely damaging to health. 

"While the research is not conclusive, we should take heed of 
the alarm bells. Most over 65s are not getting enough exercise 
which has massive implications aside from obesity, such as 
declining strength and mobility. Giving up smoking is the 
biggest thing you can do reduce your chances of developing 
coronary heart disease. 

"In today's fast-paced life, many of us say we don't have time 
to exercise or eat healthily, but unless we change our ways 
we will soon have to find time to cope with ill health."