Vitamin B12 Deficiency Anemia is a condition that occurs when the body lacks enough vitamin B12, an essential nutrient needed for red blood cell production. This deficiency can lead to a decrease in the number of healthy red blood cells, resulting in symptoms like fatigue, weakness, and pale skin. The body may not absorb vitamin B12 properly due to various factors, including certain medical conditions, dietary restrictions, or age. Treatment typically involves dietary changes or supplements to restore adequate levels of vitamin B12 and improve overall health.