Which vitamin is crucial for vision and immune function?

Vitamin A is essential for both vision and immune function due to its role in several physiological processes. For vision, it is a critical component of rhodopsin, a pigment found in the retina that is necessary for the perception of light and color. Without adequate levels of vitamin A, night blindness and other vision-related issues can arise.

In terms of immune function, vitamin A is vital for maintaining the integrity of epithelial tissues, which include the skin and mucous membranes. These tissues act as barriers to pathogens. Additionally, vitamin A plays a significant role in the development and differentiation of immune cells, particularly lymphocytes, thereby enhancing the body's response to infections.

While other vitamins like C, D, and E have various health benefits, they are not specifically known for their critical roles in vision and immune support in the same way that vitamin A is. For instance, vitamin C is more commonly linked to antioxidant defense and collagen synthesis, vitamin D is primarily associated with bone health and calcium metabolism, and vitamin E serves mainly as an antioxidant without the direct involvement in vision or immune cell development like vitamin A does.