I just used e-gel as one of my primary energy sources in my first 100 mile trail run and had great results! I never felt sick and had even energy throughout the event. I have used this product through numerous Ironman Triathlons, 50mile, 50k,100k, and now a 100 mile ultra with success. It goes down easily and the convenient pouch makes it easy for ME to control my nutrition throughout races. I know what I am getting, and it works with predictable excellence every time.