The red-flanked duiker feeds on leaves and flowers and the fruits that fall from trees, and also browses on twigs growing within one metre (yard) of the ground. Favoured food species include the wild date palm ("Phoenix reclinata"), the African peach ("Nauclea latifolia"), the Cape fig ("Ficus capensis"), the wild bauhinia ("Piliostigma thonningii"), the adanme ("Mucuna flagellipes"), the hog plum ("Spondias mombin"), the barwood ("Pterocarpus erinaceus"), the mitzeeri ("Bridelia micrantha"), the wild African black plum ("Vitex doniana"), the African custard-apple ("Annona senegalensis"), the leafflower ("Phyllanthus muellerianus"), the monkey cola ("Cola millenii"), the ackee ("Blighia sapida") and the beechwood ("Gmelina arborea"). As the red-flanked duiker eats the fruit of the Cape fig, African peach and wild date, it swallows the seeds. These pass through the gut and are present in the droppings and this is likely to be an important means of seed dispersal for these species.