A single cigarette slashes 20 minutes off your life expectancy, research suggests

If you're considering making a resolution to quit smoking in the new year, a new study might offer some helpful motivation, as it indicates that quitting smoking can extend your life expectancy. According to a new study of smokers in the UK, on average, each cigarette smoked reduces a person's overall life expectancy by about 20 minutes.

Researchers at University College London, after considering socioeconomic status and other factors, estimated that men lose about 17 minutes of life expectancy for each cigarette smoked, while women lose 22 minutes. The findings were published in a Sunday editorial in the journal Addiction. The study also points out that each cigarette smoked reduces life expectancy by an average of about 20 minutes.

Dr. Sarah Jackson, lead author of the paper and principal research fellow at the University College London's Alcohol and Tobacco Research Group, stated that if a person smokes a pack of 20 cigarettes a day, "20 minutes per cigarette, that's nearly seven hours of life lost per pack." She added, "The time they lose is time they could have spent with loved ones, and in good health." She also emphasized that smoking doesn't just affect the period of ill health in later life, but erodes the relatively healthy part of life.

The study, commissioned by the UK Department of Health and Social Care, included mortality data for men from the British Doctors Study and data for women from the Million Women Study. These studies found that people who smoke throughout their lives lose an average of about 10 years of life compared to those who never smoke. Similarly, the U.S. Centers for Disease Control and Prevention estimates that smokers in the U.S. have a life expectancy that is at least 10 years shorter than non-smokers.

Researchers say that some of the negative effects can be reversed after quitting smoking, but it's complex. New data from the UK suggests that the harm caused by smoking appears to be cumulative. The amount of life expectancy that can be recovered by quitting may depend on a variety of factors, such as age and how long someone has been smoking. "The situation is complicated in terms of recovering lost life," explained Dr. Jackson.

"People who quit at a very young age (in their 20s or early 30s) tend to have a similar life expectancy to people who have never smoked. But as you get older, you gradually lose more and more, and those are things you can't get back by quitting," she said. "However, no matter when you quit, your life expectancy will always be longer than if you continue to smoke. So, in effect, while you may not be able to reverse the life you've already lost, you're preventing further loss of life expectancy."

Jackson and her colleagues wrote in the paper that a person who smokes 10 cigarettes a day who quits on January 1st could avoid losing a full day of life by January 8th. By February 20th, they could avoid losing a full week of life, and by August 5th, they could avoid losing a full month of life. By the end of the year, they could avoid losing 50 days of life expectancy. "There's no doubt that quitting smoking is the best thing you can do for your health," Jackson said. "And the sooner you quit, the longer you'll live."

Although smoking rates have been declining since the 1960s, smoking remains a leading cause of preventable illness and death in the United States, causing more than 480,000 American deaths each year. But according to the U.S. Centers for Disease Control and Prevention, quitting smoking before the age of 40 can reduce the risk of dying from smoking-related diseases by about 90%.

An independent study published last year in the journal Nature found that smoking has short-term and long-term effects on a person's immune system, making them susceptible to infections, cancer, or autoimmune diseases. The study also found that the more someone smoked, the greater the changes to their immune response. Dr. Darragh Duffy, head of the Translational Immunology Unit at the Pasteur Institute, said that while smokers in the study saw some improvement in their immune response after quitting, it was not fully restored even after many years.

"The good news is that it does start to reset," he said when the study was released. "It's never a good time to start smoking, but if you are a smoker, now is the best time to quit."