There's conflicting information out there about flax/linseed oil - All state that the boiled variety is not food safe, but advice on raw linseed oil is quite divided. Some advice says it's fine, some not. The bottle of raw I currently own says not to ingest, so I'm taking it to be not food safe :)
One of the commonly suggested alternatives is to use mineral oil, or a combination of beeswax and mineral oil. Knowing that mineral oil is a product of crude oil refining really makes me uneasy, but at the same time I know that's an appeal to nature fallacy.
Walnut oil is sounding like an expensive but worthwhile third option.