Cracked corners of the mouth, also known as angular cheilitis, can be treated with foods rich in Vitamin B, or with vitamin supplements when the condition is caused by riboflavin deficiency, states WebMD. Vitamin B in moderate doses taken orally can help deal with this condition, states MedlinePlus.
Cracks in the corners of lips may be a sign of Vitamin B2 or iron deficiency, especially when accompanied by a swollen or unusually pale tongue, according to WebMD. Supplements and nutrient-rich foods treat these deficiencies and ease angular cheilitis. Cracked corners of lips may also be caused by some drugs and physical factors that require specific treatment, states PubMed.