I'm pretty paranoid when it comes to finding something foodsafe. Be warey of 95% of sealents. Butcher block sealer is wonderful. If you can find a foodsafe shellac or varn that doesn't deteriorate under high moisture... the really light blonde flake style shellac is the most water proof I do believe.
Or beeswax, its slightly less water proof but it works. I've sealed cutting boards and kitchen stuff with beeswax and mineral oil together. Works wonderfully
When cured Polyurethane is listed as completely food safe. Shellac and true varnish generally are not recommended for contact with food. However there may some new products on the market so who knows.