ISSA Nutritionist Practice Exam

Which vitamin is crucial for the absorption of calcium?

1. Vitamin A

2. Vitamin B12

3. Vitamin C

4. Vitamin D

The correct answer is: Vitamin D

Vitamin D plays a critical role in the absorption of calcium in the body. It facilitates the intestinal absorption of calcium and helps maintain adequate serum calcium and phosphate levels, which are necessary for normal mineralization of bone. Without sufficient vitamin D, the body cannot effectively absorb calcium from the diet, leading to potential issues like weakened bones or conditions such as rickets in children and osteomalacia or osteoporosis in adults. Other vitamins, while essential for various bodily functions, do not have a direct impact on calcium absorption like vitamin D does. For instance, vitamin A is important for vision and immune function, vitamin B12 is vital for red blood cell formation and neurological function, and vitamin C plays a significant role in collagen synthesis and antioxidant protection but does not influence calcium absorption directly. This distinction highlights the unique and essential function of vitamin D in calcium metabolism.