The best food safe oils are those that you find in the kitchen such as rape, sunflower and sesame, etc You can however buy a proprietary food safe finish but I tend to use the 'kitchen' ones as most households have them. Don't use nut oils or olive oil, the latter goes rancid after a while. As John says, if you are selling your work or i fact even giving it away you will be legally responsible if there is any adverse reaction. Hence the 'May contain nuts' on peanut butter jars (though oddly peanuts aren't nuts) and the warning that the contents are hot on coffee cups at takeaways. Just pretend that common sense doesn't exist and play safe at all times.
Pete