To keep cutting boards from harbouring bacteria or splitting, they need regular care.
If the surface looks rough, sand with the grain, using 100-grit sandpaper, and wipe clean. I like to seal cutting boards with a 50/50 blend of walnut oil (the same oil you can use on salads) and beeswax, melted in a double boiler. Oil alone takes a while to dry, but adding wax firms it up. If nut allergies are a concern, substitute food-grade mineral oil; neither will go rancid as olive or vegetable oils can.
Pour the oil-wax mixture into a jar, and let it cool to a paste. Using a piece of cheesecloth, rub the board with the paste. Sealing all sides will help to reduce warping.
Now that your cutting board looks and smells fantastic, remember that wood doesn’t like to be near heat sources; don’t store it on the toaster oven. And it’s not crazy about being wet either, so never leave it soaking in the sink.