Vitamin B12 deficiency anemia is a condition where the body lacks enough vitamin B12, a vital nutrient needed for producing red blood cells. Without sufficient vitamin B12, red blood cells become large and misshapen, leading to reduced oxygen transport in the body. This can cause symptoms like fatigue, weakness, and pale skin. The deficiency can result from various factors, including poor dietary intake, certain medical conditions, or absorption issues. Vegetarians and vegans are particularly at risk, as vitamin B12 is primarily found in animal products. Treatment often involves dietary changes or supplements to restore healthy levels.