An old favourite wooden chopping board has just come apart at a glued seam.

I've glued it together using white PVA glue, simply because I have some and
I've never heard about it being toxic. There is still a small gap on most of
the seam which I want to fill in for Hygiene reasons.

What fairly inoffensive and easy to use substance might I use for this? I
did think of using a nail varnish which I guess is just a quick drying
cellulose paint? Any other suggestions please?