Diarrhea can be caused by a variety of factors, including dietary choices, food sensitivities, parasites, and infections. Additionally, it may be the result of a vitamin deficiency, such as that of Vitamin A, B12, or folate. Vitamin A deficiency can be caused by inadequate intake of foods high in this vitamin, such as dairy, eggs, and orange and yellow vegetables. B12 and folate deficiencies can be caused by inadequate dietary intake, malabsorption, or specific genetic mutations. Treatment of the underlying cause is the key to successful management of diarrhea.