- Improvements in Healthcare
- Better Public Health Systems (e.g. improved sanitation, hygiene, and healthcare access)
- Economic Growth and Higher Living Standards (e.g. reduced poverty, hunger, and safer working conditions)
- Education and Awareness (e.g. leading to healthier lifestyles)
In 1950, the global life expectancy was around 46 years; in 2019, global life expectancy was 73.5 years, while in mainland China (the location of the study described below), it was 77.6 years.
A healthy lifestyle can significantly prolong lifespan by reducing the risk of chronic diseases, improving physical and mental health, and enhancing overall well-being. The following are specific lifestyle patterns that contribute to a longer, healthier life:
- Balanced Nutrition
- Regular Physical Activity
- Avoidance of Harmful Habits (e.g. smoking)
- Healthy Weight Maintenance
- Adequate Sleep
- Stress Management
There is a plethora of data on the association between lifestyle factors and life expectancy or mortality. However, most research has focused on middle-aged (≥45 years) and older adults (≥60 years), with limited data on people aged 80 or older. To fill this gap a recent study investigated the relationship between a healthy lifestyle and the likelihood of becoming a centenarian (living to 100 years or more) among individuals aged 80 years or older in China.
The study design took advantage of data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), which started in 1998, to conduct a case-control study. Eligible participants were those 80 years or older at the beginning of survey. Centenarians (≥100) were identified (by 2018 which marked the end of study) as cases to examine the association between modifiable lifestyle factors and the likelihood of becoming a centenarian in those aged 80 years and older; the controls were those who did not reach 100 years old but were matched by age, sex, and year of entry to the cases. There were 5222 participants in total (1454 cases and 3768 controls).
A healthy lifestyle score (HLS) was constructed from five lifestyle components: smoking status, alcohol use, exercise, dietary diversity, and body mass index (BMI). Each lifestyle component had three possible values: 0, 1, and 2 with higher numbers indicating a better (more healthy) score. Thus the total scores ranged from 0 to 10, and each subject was given an HLS score based on survey data during the study.
A post-hoc adjustment was made when initial analysis showed that two of the five lifestyle components, alcohol use and BMI, did not associate with longevity to create a revised lifestyle score (HLS-100) consisting of the three components smoking status, exercise, and dietary diversity with a total score between 0 and 6.
Additionally, data on participants' sociodemographic backgrounds were collected, including age, gender, place of residence, education level, marital status (whether married or not), and any long-term health conditions. These health conditions included hypertension, diabetes, heart disease, and cancer. They served as covariates in the analysis to mitigate possible confounding between a factor like a chronic health condition and one of the HLS lifestyle components.
An adjusted odds-ratio (AOR, adjusted for sociodemographics) was calculated based on the HLS score of the centenarians compared to the controls. Higher HLS scores were associated with an increased likelihood of becoming a centenarian (P < .001). The AOR for the highest (8-10) group versus the lowest (0-5) group was 1.33 (95% CI, 1.10-1.62). Interestingly as noted above, there were consistent associations with never smoking, exercise, and dietary diversity, but no significant associations for alcohol use or BMI.
As a result the researchers constructed the HLS-100 score using just smoking status, exercise, and diet. Among the lowest HLS-100 group (score 0-2), 373 of 1486 individuals became centenarians; among the highest HLS-100 group (score 5-6), 276 of 851 individuals became centenarians (Figure 1). The AOR for becoming a centenarian for the highest versus the lowest HLS-100 group was 1.61 (95% CI, 1.32-1.96; P < .001).
Importantly, this positive correlation showed a dose-response relationship with each increase in HLS corresponding to a greater chance of becoming a centenarian (Figure 1). Furthermore, this association was not overly dependent on any one lifestyle factor and was consistent across sociodemographic characteristics including chronic health conditions.
In summary, the authors conclude:
“In this nested case-control study of people aged 80 years or older in China, a healthier lifestyle score was associated with a higher likelihood of becoming a centenarian, underscoring the importance of adherence to a healthy lifestyle for better health outcomes even at very advanced ages. Developing appropriate intervention strategies targeting lifestyle improvement to promote health may be universally beneficial across different life stages."
These findings were generally consistent with previous research showing that a healthier lifestyle is linked to lower mortality in older adults. More specifically, not smoking, exercise, and diet have been found to associate with longevity in other studies with younger subjects. In terms of caveats, participants' lifestyle behaviors during their younger years, which was not recorded, may impact the results.
Finally, the authors speculate that in older adults, BMI may not be a reliable indicator of lifestyle but may instead reflect issues like malnutrition or chronic conditions, highlighting the need to redefine optimal BMI for the elderly. In other words, a lower BMI elderly person may be in poor health because of a condition such as loss of appetite.
Figure 1. The association between the revised healthy lifestyle score (HLS-100) and living to 100. The adjusted odds ratio (AOR) was 1.2 for the intermediate group (3 or 4 on HLS-100) and 1.6 for the group with the best lifestyle score (5 or 6) compared to the least favorable group (Li et al. JAMA Network Open, 2024).
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