The effects of smoking on health and longevity have been well studied. It is clear that smoking significantly increases risks for various diseases and can shorten lifespan. However, what happens when a smoker quits? Do former smokers live as long as people who never smoked? Or does the damage from smoking persist even after quitting? In this article, we will examine the research on how quitting smoking affects longevity compared to non-smokers.
What are the health risks of smoking?
Smoking is associated with a variety of adverse health effects that can shorten lifespan. Some key facts about smoking risks:
- Smoking increases risk of lung cancer by 25x compared to non-smokers.
- 90% of lung cancer deaths are attributable to smoking.
- Smokers have a 12-13x higher risk of dying from chronic obstructive pulmonary disease (COPD).
- Coronary heart disease risk is 2-4x higher for smokers.
- Smoking causes diminished overall health, lung function, and quality of life.
In addition to cancer and heart disease, smoking also increases risks for stroke, respiratory infections, diabetes complications, reproductive problems, osteoporosis, cataracts, and more. It is estimated that smoking shortens lifespan by at least 10 years on average compared to never smoking.
What health improvements occur after quitting smoking?
Fortunately, quitting smoking can reverse some of these adverse effects and lead to health improvements:
- Within 2 weeks to 3 months after quitting, lung function and circulation improves.
- COPD risk is reduced compared to continued smoking.
- After 1-2 years smoke-free, excess risk of coronary heart disease is cut in half.
- Stroke risk can fall to that of a non-smoker after 2-5 years.
- Risk of lung cancer falls about 30-50% after 10 years smoke-free.
- Risk of cancer of the mouth, throat, esophagus, bladder, kidney, and pancreas also declines.
So while smoking leads to long-term organ damage and disease risks, quitting can bring about considerable healing and risk reduction over time. But does this risk reduction translate to former smokers having lifespans comparable to never smokers?
Do former smokers live as long as never smokers?
Research has compared the lifespans of current smokers, former smokers (“quitters”), and people who never smoked. The findings show that while quitters gain back years of life compared to continuing smoking, their lifespan is still generally shorter than never smokers.
Some key study results:
- A 2017 study found that lifetime smoking shortened lifespan by 9.6 years for women and 7.6 years for men. Quitting before age 35 reduced loss of life to about one year lost. Quitting at middle age still reduced lifespan by 2-3 years.
- A 50-year study by the American Cancer Society found that quitters at around age 35 gained 9 years of life, and those who quit around age 65 gained 3 years, compared to continuing smokers. But their overall lifespan was still shorter than never smokers.
- Data analyzed from the U.S. National Health Interview Survey in 2019 estimated that current smokers lose 9.8 years of life, compared to 6.4 years lost for those who quit before age 45.
Why do former smokers still have reduced longevity?
There are a few reasons why former smokers may have shorter average lifespans than never smokers, even after quitting:
- Smoking causes irreversible damage such as lung scarring that persists after quitting.
- Smokers develop genetic mutations from cigarette smoke that may linger.
- It takes years for risk of smoking-related diseases like heart disease and lung cancer to drop significantly.
- Those who quit often have already smoked for many years, leading to chronic disease risks.
Essentially, quitting prevents further smoking-related damage, but it cannot always undo decades of smoking or return health to what it would have been as a never smoker.
Does the age at which you quit impact longevity?
Many studies have shown that the earlier you quit smoking, the more life expectancy improves:
- Quitting before age 40 avoids more than 90% of excess early death risk from continued smoking.
- Quitting by age 45 avoids nearly all the excess risk of death while smoking until age 65.
- Quitting by age 54 still avoids about two-thirds of the excess risk of smoking until age 65.
- Even quitting as late as age 65 gains an average of 3-4 years of life compared to those who continue smoking.
This demonstrates the substantial benefits of quitting smoking as early as possible. Those who smoke through middle age or beyond still gain longevity benefits from quitting, but to a lesser extent compared to never smokers.
How much does smoking shorten lifespan on average?
Many studies have quantified the average number of years lost due to smoking compared to never smokers:
- Men who smoke may lose 13.2 years of life on average compared to never smokers.
- For women, average life loss from smoking may be 14.5 years.
- Lifelong smokers have a 50% chance of dying prematurely compared to never smokers.
- Heavy smokers (>20/day) can lose up to 25 years of life expectancy.
However, it is important to note that quitting smoking at any age gains back years of life compared to continued smoking.
Life expectancy for current, former, and never smokers
Here is a table summarizing average life expectancy at age 40 for men and women based on smoking status:
| Smoking Status | Men | Women |
|---|---|---|
| Current Smokers | 77 years | 80 years |
| Former Smokers | 80 years | 83 years |
| Never Smokers | 84 years | 86 years |
This illustrates that on average, smokers lose 6-7 years of life expectancy compared to never smokers. Quitting regains 2-3 years, but former smokers still lag behind never smokers in lifespan.
How much does smoking shorten life expectancy for chronic diseases?
In addition to overall mortality, smoking also shortens life expectancy for those diagnosed with major chronic diseases:
- For lung cancer, smoking reduces life expectancy by 10 years on average.
- COPD patients who smoke lose 7 years of life compared to never smokers.
- Smokers with coronary heart disease lose 3 years of life expectancy.
Quitting smoking at diagnosis of these diseases adds years back compared to continued smoking. But former smokers with these conditions still tend to die earlier than never smokers.
Do genetics impact longevity effects of smoking?
Research suggests genetics may play a role in an individual’s vulnerability to effects of smoking on lifespan. Key findings:
- Studies of identical twins found that smoking shortened life more in some pairs than others.
- Certain gene variants appear linked to greater smoking-related lung cancer and heart disease risks.
- But evidence is limited, and how much genes versus lifestyle affects smoking impact on longevity is still undetermined.
More research is needed on genetic factors. But it appears smoking likely cuts lives short regardless of genetic makeup – and quitting improves longevity regardless.
How does smoking affect life expectancy for men versus women?
Some research suggests there may be gender differences in smoking effects on lifespan:
- Men may lose about 1-4 more years of life on average than women from smoking.
- However, other studies show comparable life expectancy loss for male and female smokers.
- Women may gain slightly more years back from quitting smoking before age 40.
- But evidence is mixed, and more research is still needed in this area.
Overall, both men and women can substantially improve their lifespan by quitting smoking compared to continuing the habit.
Does the number of years smoking affect longevity?
Yes, the number of years an individual smokes also impacts life expectancy:
- Lifetime smokers lose 4x as many years of life as people who smoke less than 10 years.
- Heavy smokers (>40 cigarettes/day) have a lifespan up to 25 years shorter than never smokers.
- Every 10 years of smoking increases risk of lung cancer 2-3x.
- Long-term smoking of any intensity leads to disease risks and reduced lifespan.
The implications are that both smoking intensity and duration take a toll. So while quitting after many years of heavy smoking still improves health, it cannot restore never smoker longevity.
Can former smokers have the same life expectancy as never smokers?
Based on extensive research to date, it appears unlikely that former smokers can achieve identical longevity to never smokers across the population. The key reasons are:
- Smoking causes irreversible organ damage that persists after quitting.
- It takes many years for risks of smoking-related disease to decline after quitting.
- Most quitters smoked for 20+ years before quitting, leading to chronic disease likelihood.
- Studies consistently show 3+ years lower life expectancy for quitters versus never smokers.
However, it remains possible that some individual former smokers may achieve never smoker life expectancy, depending on their smoking history, genetic factors, and lifestyle changes after quitting. But at the population level, studies have not observed this parity of longevity.
Can smoking cessation fully reverse health damage?
While quitting smoking leads to considerable health improvements and lowered disease risks, the evidence indicates it is unlikely to fully reverse all accumulated damage from smoking for most people:
- Lung function improves but long-term deficits typically persist after quitting.
- Cancer risks decline but remain elevated compared to never smokers.
- Cardiovascular risks are reduced but not typically restored to never smoker levels.
- In general, those who smoked longest and most heavily retain more residual damage.
Complete reversal of harm would likely require quitting after only brief, low-intensity smoking. But for heavy, long-term smokers, residual effects on health persist after cessation in most cases.
Can former smokers regain the same lung function?
One important measure is whether lung function can return to never smoker levels after quitting:
- After around 1 year smoke-free, FEV1 lung function improves 5-10%.
- But total lung capacity remains reduced, and lung scarring cannot be reversed.
- Lifelong smokers develop permanent lung function loss of about 10-20%.
- Over time, FEV1 decline among quitters approaches levels of never smokers.
- So while lung function partially recovers, complete restoration to never smoker status does not occur.
How much does quitting smoking reduce cancer risk?
Cancer risks decline significantly but do not typically reach never smoker levels after quitting:
- Within 5 years of quitting, oral, throat, esophagus cancer risks drop 50%.
- 10 years after quitting, lung cancer mortality risk decreases by 30%.
- Bladder cancer risk is halved after only a few years smoke-free.
- Stomach cancer risk declines slowly over 20 years after quitting.
Does cardiovascular risk revert to normal after quitting?
For cardiovascular disease, quitting smoking reduces but does not eliminate the excess risk caused by smoking:
- Just 1 year after quitting, heart disease risk drops by half.
- After 15 years smoke-free, risk approximate never smoker levels.
- But lifetime smokers retain some residual damage to heart and blood vessels.
- And risks remain higher than never smokers for those with long smoking histories.
So while substantial healing occurs, truly normal cardiovascular function is difficult to fully regain after long-term smoking.
How does smoking cessation affect COPD prognosis?
For patients with chronic obstructive pulmonary disease (COPD), quitting smoking improves prognosis:
- Quitting reduces COPD progression and risk of hospitalization.
- Lung function decline is slower compared to patients who continue smoking.
- Quitters have improved COPD mortality rates versus current smokers.
- But overall lifespan remains shorter than never smokers due to residual lung damage.
So smoking cessation provides benefit but does not restore never smoker longevity for those with COPD.
Does quitting smoking add years of life for the elderly?
It is never too late to gain health benefits from quitting smoking, even at advanced age:
- People who quit smoking by age 54 still avoid two-thirds of excess mortality risk.
- Quitting at age 65 adds 3-4 years of life compared to continued smoking.
- Also improves quality of life by reducing COPD symptoms.
- Elderly quitters have better physical function than continuing smokers.
So while the elderly may not recover never smoker longevity, quitting smoking still provides measurable longevity and quality of life advantages even late in life.
Conclusion
In conclusion, while former smokers gain substantial longevity and health benefits versus continuing smokers, they do not typically achieve the life expectancy of never smokers. Quitting at younger ages provides the most benefit, largely eliminating the smoking-related excess mortality under age 40. However, quitting later in life still adds years compared to those who continue smoking. And smoking cessation improves quality of life at any age by reducing risks of chronic lung and heart disease. So the evidence clearly indicates that it is always advantageous to quit smoking, even later in life. While former smokers should expect a few years less longevity compared to never smokers on average, cessation can still help them live healthier, longer lives than if they had continued smoking.