He [John the Baptist] will be great before the LORD and he may not drink wine or strong drink…(Luke 1:15)
The prohibition against drinking intoxicants is one of the hallmarks of the nazirite as recorded in the Torah and rabbinic tradition. According to Numbers 6, a nazirite must abstain from everything that is obtained from the grapevine: he may not drink wine, wine vinegar or grape juice, he may not eat grapes fresh or dried, or even the seeds or skins of grapes. He also is not allowed to cut his hair or come in contact with a corpse during his entire term as a nazirite.
The Mishnah seems to indicate that the vow to abstain even from specific parts of the grape implies acceptance of the entire nazirite regimen. According to Nazir 1:2, even if one vows: “I will abstain from eating grape seeds and grape skins…, he becomes a nazirite.”