If the tongue is too smooth, the taste buds are red and raised, or the sides of the tip of the tongue are yellow or white, it indicates a deficiency of folic acid and iron.
Oral signals: If the corners of the mouth are red, chronically cracked, and the lips and tongue are painful, it may be angular cheilitis caused by malnutrition. This is mostly caused by a lack of iron, vitamin B2, and vitamin B6.