How fresh is your produce? Choose vegetables and fruits that have deep, rich colors, such as ruby-red, juicy watermelon. Bright orange carrots, dark green broccoli, and vivid blue berries have higher nutrient contents than paler produce. Frozen, plain vegetables are your best option when very fresh produce is not available. Finally, canned vegetables are alright, but use the canning liquid, since much of the nutrients have leached into this juice.