which of the following vitamin increase the retention of calcium and phosphorous ions in the blood

which of the following vitamin increase the retention of calcium and phosphorous ions in the blood:

• A- Vit A.
• B- Vit B12.
• C- Vit. D.
• D- Vit C.

The correct answer is C- Vit. D.

Vitamin D plays a crucial role in regulating calcium and phosphorus levels in the blood. It enhances the absorption of calcium from the intestines and promotes its incorporation into bones. Additionally, vitamin D helps maintain adequate levels of phosphorus in the bloodstream.

Here's a detailed explanation of how vitamin D affects calcium and phosphorus metabolism:

Intestinal Calcium Absorption:

Vitamin D stimulates the production of calbindin, a protein that binds to calcium ions and facilitates their transport across the intestinal wall into the bloodstream. Without adequate vitamin D, calcium absorption from the intestines is significantly reduced.

Bone Mineralization:

Vitamin D promotes the incorporation of calcium into bone tissue. It enhances the activity of osteoblasts, the cells responsible for bone formation, and ensures proper mineralization of the bone matrix.

Phosphorus Regulation:

Vitamin D indirectly influences phosphorus metabolism by regulating the activity of parathyroid hormone (PTH). PTH is a hormone that controls calcium and phosphorus levels in the blood. When vitamin D levels are low, PTH secretion increases, leading to increased phosphorus reabsorption from the kidneys and reduced excretion of phosphorus in the urine.

Therefore, vitamin D is essential for maintaining proper calcium and phosphorus balance in the body. It promotes intestinal calcium absorption, facilitates bone mineralization, and regulates phosphorus levels, ensuring that these minerals are available for various physiological processes.