If your tongue appears to be much redder than its typical pink hue, there's a chance you may have a blood disorder known as pernicious anemia. This disorder affects your body's ability to make enough healthy red blood cells due to a lack of a specific protein called intrinsic factor.
Your body needs this protein to absorb vitamin B12, a necessary nutrient that keeps your nervous system working properly and creates red blood cells. When it lacks intrinsic factor protein, the absorption of B12 is diminished, inhibiting the production of red blood cells in your body.