What does a healthy lifestyle achieve for life expectancy? It is surprisingly hard to answer that question for humans. Researchers can't construct carefully cultivated lifestyle choice groups and follow them from birth to death. Instead, messy and imperfect vaults of epidemiological data must be fed into complicated statistical machinery, using strategies that are, at the end of the day, guided by a healthy dose of intuition and common sense. Different groups can and do produce widely different answers to questions regarding additional years added by diet, exercise, or other factors. One has to survey the field in aggregate, averaging over dozens of studies to try to get an idea of what might or might not be the reality. So take this one study in that context - the number produced at the end is large in comparison to other studies I've seen in past years, but the authors are trying to consider all of the major effects rather than just one.
Maintaining a healthy lifestyle, including eating a healthy diet, regular exercise, and not smoking, could prolong life expectancy at age 50 by 14 years for women and just over 12 years for men, according to new research. Heart disease and stroke are major contributors to premature death in this country, with 2,300 Americans dying of cardiovascular disease each day, or one death every 38 seconds. Researchers point out that the U.S. healthcare system focuses heavily on drug discovery and disease management; however, a greater emphasis on prevention could change this life expectancy trend.
To quantify the effects of prevention, researchers analyzed data from two major ongoing cohort studies that includes dietary, lifestyle and medical information on thousands of adults in the Nurses' Health Study and the Health Professionals Follow-up Study. These data were combined with National Health and Nutrition Examination Survey (NHANES) data, as well as mortality data from the Centers for Disease Control and Prevention (CDC), to estimate the impact of lifestyle factors on life expectancy in the U.S. population. Specifically, they looked at how the following five behaviors affected a person's longevity: not smoking, eating a healthy diet (diet score in the top 40 percent of each cohort), regularly exercising (30+ minutes a day of moderate to vigorous activity), keeping a healthy body weight (18.5-24.9 kg/m), and moderate alcohol consumption (5-15 g/day for women, 5-30 g/day for men).
Over the course of nearly 34 and 27 years of follow-up of women and men, respectively, a total of 42,167 deaths were recorded, of which 13,953 were due to cancer and another 10,689 were due to cardiovascular disease. Following all five lifestyle behaviors significantly improved longevity for both men and women. Compared with people who didn't follow any of the five lifestyle habits, those who followed all five were 74 percent less likely to die during the follow-up period; 82 percent less likely to die from cardiovascular disease and 65 percent less likely to die from cancer. There was a direct association between each individual behavior and a reduced risk of premature death, with the combination of following all five lifestyle behaviors showing the most protection.
Between 1940 and 2014, Americans' life expectancy at birth rose from around 63 years to nearly 79 years. However, researchers believe the improvement of life expectancy would be even larger without the widespread prevalence of obesity - a known risk factor for heart disease, stroke, and premature death. "It is critical to put prevention first. Prevention, through diet and lifestyle modifications, has enormous benefits in terms of reducing occurrence of chronic diseases, improving life expectancy as shown in this study, and reducing healthcare costs."