Intrinsic factor is a protein produced by the stomach's parietal cells. It plays a crucial role in the absorption of vitamin B12, which is essential for red blood cell formation and proper nerve function. Without intrinsic factor, the body cannot effectively absorb vitamin B12 from food, leading to potential deficiencies. A deficiency in intrinsic factor can result in a condition known as pernicious anemia. This condition is characterized by a reduced number of red blood cells, fatigue, and neurological issues. Treatment often involves vitamin B12 injections or high-dose oral supplements to bypass the need for intrinsic factor.