Running a marathon or an ultra-marathon expends not only energy but creates the monotony of drinking sweetened energy drinks. Our bodies often crave something different, something natural, full of energy like an orange.
In the days before energy drinks became available, runners and athletes used natural alternatives to boosting their energy. Oranges we often used because they just worked. Somehow Oranges made an athlete feel refreshed and ready go again.
Over the years nothing has changed and especially after hours of running an Orange is a very welcome site for any runner.
Oranges contain vitamin C that helps with repair the muscle damage, maybe not that quickly while you are running but the energy derived from one or two quarters of an Orange will certainly help you.
The golden rule is try eating an Orange in training and see if it works before you run a race.