CALCA and migraine disorder: The strengths of this study are the prospective- double blind, placebo- controlled design, using a safe daily dosage of vitamin D as a somewhat inexpensive and available over-the-counter supplement, exploring CGRP levels as the dominant indicator of migraine pathogenesis, enrolling the study participant following examinations by expert headache-specialist neurologists, and confirming episodic migraine diagnosis based on the most recent ICHD criteria (ICHDIII).