Starting Smoking Before 20 Doubles Heart Attack Risk, Major Study Reveals
New research has uncovered alarming evidence that beginning to smoke cigarettes before reaching twenty years of age can inflict severe, long-lasting damage to cardiovascular health. This damage persists even if individuals have abstained from smoking for decades, according to a comprehensive study published in the prestigious journal Nature.
Groundbreaking Research on Early Smoking Initiation
Scientists from Seoul National University Hospital in South Korea conducted an extensive analysis of health data from over 9.2 million adults. Their primary objective was to investigate the specific link between the age at which someone first starts smoking and their subsequent risk of experiencing a heart attack or stroke later in life.
While the connection between smoking and cardiovascular disease is already well-documented, there has been a significant gap in research focusing specifically on the risks tied to the age of smoking initiation. This study aimed to fill that crucial void.
Study Methodology and Participant Profile
The research team examined data from 9,295,979 Korean adults who had participated in a national health screening programme in 2009. At the outset of the study, none of these individuals showed any evidence of pre-existing heart disease or had previously suffered a stroke. Within this vast cohort, approximately 3.7 million were identified as smokers.
Among the smoking group, the findings were particularly striking:
- Nearly a quarter (25%) had started smoking before the age of 20.
- Two per cent had initiated the habit before reaching 15 years old.
The researchers then tracked this population to identify who subsequently suffered a heart attack, a stroke, or died from any cause during a follow-up period of up to 9.3 years.
Compounding Health Risks for Early Smokers
To build a comprehensive health profile for each participant, the study accounted for multiple factors. These included estimated lifetime smoking intensity (measured in packs per year), age, sex, body weight, blood pressure, cholesterol levels, diabetes status, alcohol consumption, and exercise frequency.
The analysis revealed a clear and concerning trend: the highest cardiovascular risks were observed in individuals who started smoking before age 20 and were classified as heavy smokers. Heavy smoking was defined as consuming more than 20 packs of cigarettes annually.
Even former heavy smokers who had quit remained at a significantly elevated risk. When compared to non-smokers, this group faced more than double the risk of suffering a heart attack and an approximately 80% higher risk of stroke. They were also at a substantially greater risk of death during the study's follow-up period.
The Critical Impact of Starting Age
The research highlighted a stark contrast between different smoking groups. Heavy smokers who started young were in a worse position than heavy smokers who did not begin until adulthood (defined as age 20 and over). However, the most vulnerable group were those who started smoking before their fifteenth birthday. This group exhibited the highest risk of stroke, heart attack, overall cardiovascular disease, and death.
Importantly, these elevated risks persisted even after statistical adjustments were made for the total amount smoked over a lifetime. This means that individuals who started young but quit relatively soon after were still at a higher risk. This led the researchers to a critical conclusion: the earlier a person starts smoking, the more damage each additional cigarette causes over time.
Biological Mechanisms Behind the Increased Risk
The study authors proposed several biological explanations for these findings. They suggested that blood vessels in young people may be more susceptible to damage from tobacco smoke. Furthermore, the arterial damage that is a primary cause of cardiovascular disease can begin accumulating during childhood and adolescence.
Initiating smoking at a young age can also trigger long-term, systemic inflammation, adversely affect cholesterol profiles, alter blood clotting mechanisms, and foster a stronger addiction to nicotine. The study also noted that individuals who start smoking earlier in life tend to exhibit other less healthy lifestyle patterns, such as higher alcohol consumption, lower physical activity levels, and a greater intake of processed foods.
Study Limitations and Public Health Implications
It is important to note that, as an observational study based on a one-time questionnaire, the research cannot definitively prove causation. However, the robust associations identified provide powerful evidence for public health policy.
Lead author Jung Hun Koh expressed hope that this research will bolster anti-smoking campaigns specifically targeted at younger demographics. 'Early initiation of smoking may imply the possibility of stronger addiction to the harmful social behaviour,' Koh stated. 'In line with these findings, our analysis supports age- and intensity-dependent effects of smoking on the onset of cardiovascular diseases. Moreover, we showed that smoking initiation in adolescence and in early adulthood both significantly elevate the risks of cardiovascular events and mortality compared to starting smoking at age 30 or above.'
Broader Context: Confirming Global Health Concerns
This Korean study arrives shortly after similar concerning research emerged from the United States. A separate paper from researchers at the Johns Hopkins Ciccarone Center for Prevention of Cardiovascular Disease in Baltimore analysed data from 22 studies involving 330,000 people over nearly two decades.
That research, led by Professor of Cardiology and Epidemiology Dr. Michael Blaha and published in PLOS Medicine, documented over 125,000 deaths and 54,000 cardiovascular events. It concluded that even very low-intensity smoking—defined as between two to five cigarettes per day—was associated with a 50% higher risk of heart failure and a 60% higher risk of death from any cause, compared to never smoking.
Dr. Blaha's team found that while cardiovascular risk drops most sharply in the first decade after quitting, it never fully returns to the level of a never-smoker, even thirty years after cessation. This body of research collectively underscores a vital public health message: when it comes to smoking, the sooner one quits—or better yet, never starts—the better for long-term heart health.
