Final answer:
Vitamin D is essential for the absorption of calcium from the intestine, and its deficiency can lead to significant bone health issues.
Step-by-step explanation:
The nutrient necessary for the absorption of calcium is vitamin D. Vitamin D increases calcium and phosphorus absorption from the intestine by promoting the synthesis of a specific calcium binding protein that participates in the active transport of calcium across the small intestinal mucosa.
A diet deficient in vitamin D or a disorder that reduces vitamin D absorption can lead to decreased calcium absorption, impairing bone health and potentially leading to conditions such as rickets in children and osteomalacia in adults, both of which can contribute to osteoporosis.