In　lattice　systems,　the　effects　of　optical　phonons　on　heat　transport　are　usually　neglected　due　to　their　relatively　small　group　velocities　compared　with　acoustic　phonons,　or　even　assumed　to　be　negative　because　introducing　optical　phonons　may　simultaneously　reduce　the　group　velocities　of　acoustic　phonons.　In　order　to　well　understand　the　role　played　by　optical　phonons,　we　propose　a　one-dimensional　anharmonic　lattice　model　with　alternating　interactions,　where　the　optical　phonons　can　be　conveniently　tuned.　We　find　that　in　contrast　to　previous　studies,　the　optical　phonons　(in　coordination　with　the　nonlinearities)　can　enhance　heat　transport　in　the　thermodynamical　limit,　suggesting　that　optical　phonons　can　also　play　an　active　role.　The　underlying　mechanism　is　related　to　the　effects　of　two　kinds　of　nonlinear　excitations,　i.e.,　the　optical　and　the　gap　discrete　breathers　(DBs).　These　DBs　release　energy　and　in　turn　facilitate　heat　transport.　©　2013　American　Physical　Society.