Advice to a marathon runner

Imagine that you have a 25 years old brother who has signed up for the local annual Marathon this year. He is physically fit and his physician gave him the OK for the race. This is his first time joining the race and he is quite excited about the event. However, he is also concerned about needed nutrients that he heard his friends talking about. He did not want to ask his friend for fear he would sound naà¯ve among his friends. Since you are taking a nutrition course, he seeks your advice regarding nutritional needs before, during, and after the race.