Summary
Highlights
Initially, genetics were thought to be the most significant factor in longevity. However, recent studies, including one in Human Genetics, suggest that genetic factors account for only 20-30% of adult lifespan variation. As we learn more about lifestyle's impact, the perceived importance of genetics continues to decrease, possibly to 10-15%.
Contrary to past beliefs that it was hard to course-correct in older age, new research shows that significant lifestyle changes at any age can have substantial benefits. A New England Journal of Medicine study on smoking cessation demonstrated that quitting at 45-54 still added 6 years to life expectancy. Similarly, increasing physical activity, even from a sedentary baseline, significantly reduces all-cause mortality. For instance, moving from no exercise to 150 minutes per week over five years reduces all-cause mortality by 24%.
While resveratrol was once highly touted, a JAMA study showed no difference in mortality or inflammatory markers between those who consumed the most and least resveratrol. This highlights the difference between rodent model findings and human studies, emphasizing the need for human trials to confirm benefits.
Previous studies suggesting a U-shaped curve for alcohol consumption (where moderate drinking prolonged life) often suffered from reverse causality, grouping former heavy drinkers with health issues into 'non-drinker' categories, or misclassifying occasional drinkers as 'moderate'. A 2023 JAMA study of 107 studies and 4.8 million people found that 25 grams of ethanol per day (about 1-2 drinks) had no positive impact on life expectancy, and higher consumption had a significantly negative impact on all-cause mortality.
A study in 'Nutrients' on monkey data suggested that caloric restriction primarily matters if the diet is poor. If the diet is good and whole-food-based, caloric restriction doesn't necessarily improve lifespan. However, for most people consuming processed foods, caloric restriction remains a relevant strategy for longevity. The overall message is that a wholesome, natural diet can enable the body to self-regulate calorie intake more effectively.