If you mean to improve the flavor of your semen, yes.
In an issue of Playgirl magazine (April 2006), Kimberly Pflaum (the articles author) performed a "grueling" experiement on her husband over the course of a month by having him eat diferent types of food 24 hours prior or her giving him oral sex.
This was her conclusion:
"Clean living, makes for tastier seminal fluid. A man must eat a healthy diet and include a broad range of nutrients in meal plans; however, if we know 12 to 24 hours in advance that a BJ is on the menu, he should gorge on fruits, sweets and veggies like carrots, parsley and celery and stay well hydrated. Foods higher in sugar translate to sweeter seminal fluids."
Though, clean living implies this, he shouldn't smoke either. Or, if he does, he should quit for 24 hours prior to a BJ, and of course, avoid alcohol.
Smoking and alcohol are two factors that can make for bitter and unpleasant tasting seminal fluid, and I speak from personal experience on that one.