dear member,
it is believed that non-veg food gives rise to tamasic qualities in a person.whereas tulasi beads r of satvic nature.i.e. satavic qualities r more predominate in it.
so a person having more tamasic qualities ,while using tulasi beads for japa will not be benefitted by it.
so it is suggested maybe that he use neem beads which r rajasic in nature.