As long as they remain under their Nazirite vow, they must not eat anything that comes from the grapevine, not even the seeds or skins.
OJBKol hayamim of his nazir (vow as a nazir) shall he eat nothing that is made of the gefen hayayin, from the seeds even to the grape-skins.
Onkelos (Etheridge)All the days of his nazirate he may not eat of aught that is produced by the vine (wine tree), from its kernels to its expressed juice.
T4TYou must not eat anything that comes from grapevines, not even the skins or seeds of grapes, during the time that you are a Nazir-man.