Clinical Nutritionist Practice Test 2025 - Free Practice Questions and Study Guide

Vitamin A is crucial for vision due to its role in the formation of rhodopsin, a protein in the retina that is sensitive to light. This vitamin is integral to the process of converting light into visual signals, which the brain interprets as images. A deficiency in vitamin A can lead to a range of vision problems, including night blindness and more severe conditions that can impair overall eyesight.

While vitamin C, vitamin D, and vitamin K are important for various bodily functions, they do not have the specific and direct role in vision that vitamin A does. Vitamin C is significant for its antioxidant properties and its role in collagen synthesis, vitamin D is essential for bone health and calcium regulation, and vitamin K is important for blood clotting and bone metabolism. None of these vitamins are directly involved in the visual processes that are dependent on adequate levels of vitamin A.