Folate deficiency can contribute to canker sores because it plays a vital role in cell growth and repair, including the maintenance of the mucous membranes in the mouth. Without enough folate, the oral tissues may become more prone to damage and slower to heal, increasing the risk of developing canker sores. Additionally, folate deficiency can impair the immune system, making it harder for the body to respond to inflammation or infection, which are potential triggers for canker sores.