oranges are allergenic and apparently very unhealthy overall (perhaps due to hybridization), based on EDS data. They're contraindicated for blood type A. Tangeretin (bioflavanoid in oranges) may interfere w/tamoxifen, but it's effective w/brain tumors. Particularly avoid nonorganic Florida oranges.
They are mucus (phlegm) inducing.
Grapefruits are much better
grapefruits are high in pectin, potassium, & coumarins; is very-low-glycemic; pink/red grapefruit's high in lycopene; fresh-pressed grapefruit juice is the juice most commonly consumed by people who have "spontaneous remissions".