Why Red Blood Cells Live Only 120 Days: The Role of the Missing Nucleus

Red blood cells (RBCs) lack a nucleus, which limits their lifespan to about 120 days. The nucleus houses DNA and directs essential cellular functions—DNA replication, transcription, translation, and repair. Without it, RBCs cannot divide, synthesize new proteins, or fix damaged DNA.

As RBCs age, they accumulate oxidative damage and lose membrane flexibility. They are eventually removed by macrophages in the spleen and liver (a process called eryptosis). The body continuously produces new RBCs in the bone marrow to replace them.