"It's crucial to get enough vitamin B6 into your diet leading up to your period and during your period as well," Tracy Lockwood Beckerman, MS, RDN, author of "The Better Period Food Solution, told POPSUGAR. She explained that this is due to the vitamin's ability to thwart "the negative symptoms associated with PMS, such as moodiness, cramping, and fatigue." Along with foods like oranges, nuts, and seeds, oats are a natural source of vitamin B6.