Brain Fog or B12? The Hidden Nutrient Deficiency Mimicking Memory Loss

8. Physical and Digestive Signs of Deficiency
Physically, a person with B12 deficiency may have pale or slightly yellow skin (mild jaundice). Additionally, glossitis—an inflammation of the tongue that makes the surface appear smooth, red, and painful—is a classic symptom. Digestive issues such as loss of appetite and sudden weight loss are also seen in these individuals.