The best diet for sperm is a balanced, heart-healthy diet rich in fruits and vegetables, limited red meats, and minimal fried foods or other processed foods high in saturated fats.  A vegetarian or pescatarian diet are both very healthy diets for sperm.  Foods to consider adding to an otherwise balanced, heart-healthy diet would be any green leafy vegetables that are high in antioxidants.  Because of the long transit time from production to ejaculation which takes around 74 days, diet changes are not observed in a semen sample for a minimum of 3 months.