Which vitamin is fat-soluble and essential for calcium absorption in the gut?

Which vitamin is fat-soluble and essential for calcium absorption in the gut?

• A. Vitamin D (calciferol)
• B. Vitamin C
• C. Vitamin K
• D. Vitamin B12

Answer: (A)

Calcium absorption in the gut relies on a fat-soluble vitamin that, in its active form, calcitriol, upregulates calcium-binding proteins in the intestinal lining to boost uptake from the diet. This vitamin is essential for proper calcium absorption and, by extension, bone health. You can get it from sun exposure, fortified foods, fatty fish, and supplements. Other vitamins listed don’t directly regulate intestinal calcium absorption: vitamin C is water-soluble and supports collagen and antioxidant defenses; vitamin K is fat-soluble and important for blood clotting and certain bone processes but not the key driver of calcium uptake in the gut; vitamin B12 is water-soluble and important for nerve function and red blood cell production.

Calcium absorption in the gut relies on a fat-soluble vitamin that, in its active form, calcitriol, upregulates calcium-binding proteins in the intestinal lining to boost uptake from the diet. This vitamin is essential for proper calcium absorption and, by extension, bone health. You can get it from sun exposure, fortified foods, fatty fish, and supplements.

Other vitamins listed don’t directly regulate intestinal calcium absorption: vitamin C is water-soluble and supports collagen and antioxidant defenses; vitamin K is fat-soluble and important for blood clotting and certain bone processes but not the key driver of calcium uptake in the gut; vitamin B12 is water-soluble and important for nerve function and red blood cell production.