Your body speaks volumes about your nutrition and health. If you are not getting adequate nutrients from your diet or if you are unable to absorb certain vitamins effectively, you may experience a sore, cracked tongue. The most common deficiencies involve the B vitamins, which help your body absorb other nutrients and convert carbs into energy.
The most common culprit for a cracked tongue is a deficiency of vitamin B-2, riboflavin. This vitamin plays a key role in helping your body use other nutrients, such as vitamin B-6, niacin, folate and iron. The Linus Pauling Institute recommends that adults get 1.1 to 1.3 milligrams of riboflavin daily, from a range of foods including milk, eggs, beef, broccoli and salmon. A deficiency of this nutrient can cause redness and inflammation of the tongue -- called magenta tongue -- as well as fissuring or cracking at the sides of the mouth.
A folic acid deficiency is quite common; it can be caused by poor nutrition, alcoholism, inflammatory bowel disease and certain medications. A deficiency of this vitamin, which is also called vitamin B-9 and folate, can cause a sore tongue. Adults need 400 micrograms of folic acid each day; breast-feeding women should get 500 micrograms a day, and pregnant women need 600 micrograms a day. Rich food sources include dark leafy greens, root vegetables, beans, whole grains, salmon and milk.