A comprehensive study conducted by researchers from Harvard T.H. Chan School of Public Health examined the influence of health habits on life expectancy using data from the Nurses’ Health Study (NHS) and the Health Professionals Follow-up Study (HPFS). These studies involved a vast number of participants over an extended period. The NHS tracked over 78,000 women from 1980 to 2014, while the HPFS followed more than 40,000 men from 1986 to 2014, resulting in a dataset of over 120,000 participants with 34 years of data for women and 28 years for men.
The researchers analyzed data on diet, physical activity, body weight, smoking, and alcohol consumption collected through validated questionnaires administered regularly in the NHS and HPFS.
The five key areas of a healthy lifestyle were chosen based on previous studies showing their significant impact on the risk of premature death. Here’s how these healthy habits were defined and assessed:
- Healthy diet: Calculated and rated based on reported consumption of healthy foods such as vegetables, fruits, nuts, whole grains, healthy fats, and omega-3 fatty acids, as well as unhealthy foods like red and processed meats, sugar-sweetened beverages, trans fat, and sodium.
- Healthy physical activity level: Measured as engaging in at least 30 minutes of moderate to vigorous activity per day.
- Healthy body weight: Defined as having a normal body mass index (BMI) falling between 18.5 and 24.9.
- Smoking: No amount of smoking was considered healthy. “Healthy” in this context referred to never having smoked.
- Moderate alcohol intake: Measured as consuming between 5 and 15 grams per day for women and 5 to 30 grams per day for men. Typically, one drink contains approximately 14 grams of pure alcohol, equivalent to 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of distilled spirits.
The researchers also incorporated data on age, ethnicity, medication use, as well as comparison data from national surveys conducted by the National Health and Nutrition Examination Surveys and the Centers for Disease Control and Prevention.
The study revealed that adopting healthy habits had a significant impact on life expectancy. Those who met all five healthy habits criteria experienced substantially longer lives compared to those who had none of these habits: 14 additional years for women and 12 additional years for men (at age 50). Individuals with none of the healthy habits were at a higher risk of premature death from cancer or cardiovascular disease.
Furthermore, the researchers calculated life expectancy based on the number of healthy habits individuals practiced. Having just one healthy habit, regardless of which one, extended life expectancy by two years for both men and women. Notably, the more healthy habits individuals had, the longer their lifespan. Numerous prior studies support these findings.
The study’s authors highlighted a significant problem in the United States, where a considerable amount of resources are invested in developing advanced drugs and treatments for diseases rather than focusing on prevention. This underscores the importance of addressing this issue.
Experts suggest that the most effective way to promote healthy diet and lifestyle changes is through public health efforts and policy changes at a population level, similar to regulations on motorcycle helmets and seat belts. While there has been some progress with tobacco and trans-fat legislation, there is often resistance from influential industries that profit from unhealthy products like fast food, chips, and soda. Advocating for guidelines and laws that encourage healthier living can have a profound impact on improving public health and reducing preventable diseases.