The WHO calls tobacco “the single most preventable cause of death in the world”—but cigarettes may also provide a handful of paradoxical, if pyrrhic, health benefits:
Smoking will probably take years off your life, but certain things in tobacco smoke may actually do the body good. Here’s what science has to say about the smoker’s paradox.
Smoking Alleviates Ulcerative Colitis but Inflames Crohn’s Disease
Broadly speaking, smoking worsens your health. But for some people who suffer from inflammatory bowel disease (IBD), smoking seems to relieve their worst symptoms.
IBD refers to a handful of chronic gut diseases. Crohn’s disease and ulcerative colitis, the two most-common forms of IBD, both result when a person’s immune system mistakenly attacks that person’s own gut. But while smoking cigarettes has exacerbates Crohn’s disease, it seems to alleviate ulcerative colitis.
Smoking Increases the Risk of Dementia, but Protects Against Parkinson’s Disease
The same toxic compounds in cigarette smoke that damage the heart and lungs also damage blood vessels and neurons in the brain. Amongst smokers who don’t succumb early to lung cancer, emphysema,
or heart attacks, smoking has been linked to an increased likelihood of developing Alzheimer’s disease, and dementia in general, later in life. What’s bad for the body, it seems, is also bad for the brain.
And yet, studies have observed that the more people smoke, the less likely they are to develop Parkinson’s disease. This inverse correlation was first observed in the 1960s, by epidemiologist Harold Kahn. When he analyzed the health insurance records of nearly 300,000 veterans,
Kahn noticed that smokers who had served in the US military between 1917 and 1940 were three-times less likely than non-smokers to have later died of Parkinson’s disease,
even though they were over ten times more likely to have died of lung cancer or emphysema than non-smokers. This finding has since been bolstered by numerous studies.
The Fickle Relationship Between Obesity and Smoking
Cigarette ads have long touted the appetite-suppressing qualities of tobacco. Even today, much of the public believes that cigarettes can be used to lose weight. Indeed, people do eat less when they smoke, and quitting smoking can cause a temporary spike in weight gain.
Four years ago, scientists finally identified how nicotine curbs the appetite via a hunger circuit in the brain, lending an explanation for decades of studies that broadly correlated smoking with lower body weight.
But the devil is in the details of this correlation. Some people smoke multiple packs a day, while others smoke only with their friends over the weekend, and it’s only on average that smokers weigh less than non-smokers.
Recent studies that examined the medical records of hundreds of thousands of people have found that heavy smoking (40+ cigarettes per day) is strongly associated with an increased risk of obesity, while light smoking (on the order of a dozen cigarettes per day) has the opposite effect.
Moreover, younger smokers do not appear to benefit from the general association of smoking and lower body weight.
False Promises: Some “Smoker’s Paradoxes” May Not Exist at All
Some smoker’s paradoxes may not be paradoxes at all. The phrase itself, “smoker’s paradox,” originally referred to the observation that smokers seem to have better short-term health outcomes than non-smokers following hospitalization for heart attacks.
But this “paradox” may have a straightforward explanation: smokers are notorious for having heart attacks earlier in life than non-smokers, when their bodies are generally more resilient.
Science bears this idea out. Smokers are hospitalized for heart attacks eleven years earlier, on average, than non-smokers, and this age gap “generally accounted” for the formers’ more favorable outcomes. Of note, most studies claim this smoking/heart attack paradox
are over 20 years old, and some doctors have argued that the age-dependency of the smoker’s paradox has been rendered irrelevant in the face of modern therapies for heart attack victims.