Any food will bring in nitrate and phosphate, they have to because it is part of fish nutrition (protein and other essentials). A high quality food will keep waste to a minimum and provide a complete and balanced diet. I only feed and recommend New Life Spectrum.
If the food is good enough you shouldn't need to supplement ANYTHING including fruits and veggies.
There are two things you can control in an aquarium that will completely make the difference between thriving and dying: water quality and food quality. If you feed NLS the food part is taken care of. If you do enough water changes to keep the nitrate under 20ppm the water quality should be taken care of too.