BBC NEWS: “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.

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{a9f0d31f6175b3e4775e11a66c07db268fb74408d6095f6b46eeec420c0e9f62} on top of the average annual shortening of telomeres.

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. “