Which vitamin deficiency is commonly associated with night blindness?

Night blindness is primarily associated with a deficiency in vitamin A. This vitamin is critical for the synthesis of rhodopsin, a photopigment found in the rod cells of the retina that is necessary for low-light and night vision. When there is insufficient vitamin A in the body, the production of rhodopsin is impaired and can lead to difficulty seeing in dim light, which is termed night blindness or nyctalopia.

Vitamin B12 is primarily involved in processes such as red blood cell formation and neurological function, while vitamin D plays a significant role in calcium metabolism and bone health. Vitamin K is primarily known for its role in blood clotting. None of these vitamins are directly related to the mechanism that supports vision in low-light conditions, distinguishing them from vitamin A, which is essential for maintaining proper vision.