Coffee and Longevity
A study published in Nature Medicine in 2017 has shown that there is a correlation between coffee consumption and increased longevity. Coffee and caffeine have anti-inflammatory properties such that they have a positive impact on chronic inflammation, a key factor in a variety of non-communicable diseases associated with aging. These include Alzheimer's disease, many forms of cancer, cardiovascular disease, osteoarthritis as well as depression.
The Effect of Roast Levels
A further study, outlined in an article in Journal of Medicinal Food, explored the impact of coffee roast levels on antioxidant and anti-inflammatory properties in coffee. Their research findings showed that the darker the roast the more of those properties are lost. Interestingly, caffeine levels themselves did not differ greatly between the light, medium, city and French roast levels.
For the maximum health benefits of coffee's anti-inflammatory and antioxidant properties the lighter roast appears to be the best choice. Lighter roasted coffees preserve more anti-inflammatory and antioxidant properties which can positively impact many diseases related to aging.
Research Article Links
The articles are fairly technical, but if you are curious to read deeper here are links to the original publications.