American Board of Family Medicine (ABFM) Practice Exam

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Which vitamin deficiency is commonly associated with night blindness?

  1. Vitamin A

  2. Vitamin C

  3. Vitamin D

  4. Vitamin K

The correct answer is: Vitamin A

Night blindness is commonly associated with a deficiency in vitamin A. This vitamin plays a critical role in the formation of rhodopsin, a pigment found in the retina that is essential for low-light and night vision. When a person is deficient in vitamin A, the synthesis of rhodopsin is impaired, leading to difficulty seeing in dim light. Vitamin A deficiency can result from inadequate dietary intake, certain malabsorption disorders, or a lack of sufficient beta-carotene in the diet, which the body can convert into vitamin A. Common sources of vitamin A include liver, fish, dairy products, and dark green or orange vegetables and fruits. While other vitamins play important roles in overall health, they are not directly linked to night blindness. Vitamin C is known for its role in collagen formation and as an antioxidant but does not affect night vision. Vitamin D is essential for calcium absorption and bone health, and vitamin K plays a key role in blood clotting. None of these vitamins contribute directly to the mechanisms behind night blindness as vitamin A does.