This is old news.
Much has been studied about CHRONIC CARDIO. Google it. Even Mark Sisson, former world class triathlete/runner has written about it.
Running long distances raises cortisol/inflammation and all the carbs you'll have to eat will lead to early diabetes/CVD.
Much better off doing terabit/CrossFit Style Sprint Repeats, weightlifting and adhering to a diet high in animal fat/protein.
Case in point: