Which vitamin is critical for the absorption of calcium?

Vitamin D is essential for the absorption of calcium in the body. It facilitates the intestinal absorption of calcium and is crucial for maintaining adequate serum calcium and phosphate levels, which are vital for normal bone mineralization. When vitamin D is present, the gastrointestinal tract becomes more efficient at absorbing calcium from the diet, enhancing overall calcium availability for various physiological processes, including bone health and muscle function.

Vitamin A and Vitamin C do not have a direct role in calcium absorption. While Vitamin A is important for vision, immune function, and cellular communication, and Vitamin C is essential for collagen synthesis and acts as an antioxidant, they do not influence calcium absorption in the same way that Vitamin D does. Vitamin K is involved in blood clotting and the regulation of calcium in bones and blood, but it is not directly responsible for the absorption process itself.