Rickets, a childhood disease characterised by soft and deformed bones, is caused by the deficiency of which vitamin?

Introduction / Context:
Vitamins play critical roles in growth and development, and deficiencies of specific vitamins lead to characteristic diseases. In children, proper bone formation requires adequate levels of certain vitamins and minerals. Rickets is a well known childhood disorder in which bones become soft, weak, and deformed. This question asks you to identify which vitamin deficiency leads to rickets.

Given Data / Assumptions:

• The disease in question is rickets, seen primarily in growing children.
• Options list carotene, cyanocobalamin (Vitamin B12), thiamine (Vitamin B1), calciferol (Vitamin D), and ascorbic acid (Vitamin C).
• We assume typical nutritional deficiency patterns and their classic associated diseases.
• Only one vitamin is directly linked to defective bone mineralisation seen in rickets.

Concept / Approach:
Vitamin D, also called calciferol, is essential for normal absorption and utilisation of calcium and phosphorus in the body. It helps maintain proper levels of these minerals in blood, which are needed for healthy bone formation. When Vitamin D is deficient, bones do not mineralise properly, leading to soft and weak bones in children, a condition called rickets. Carotene relates to Vitamin A and affects vision and epithelial health, Vitamin B1 deficiency leads to beriberi, Vitamin B12 deficiency causes pernicious anaemia, and Vitamin C deficiency results in scurvy. Therefore, calciferol (Vitamin D) is the correct answer.

Step-by-Step Solution:
Step 1: Recall the main function of Vitamin D: regulating calcium and phosphorus metabolism for bone health. Step 2: Understand that in growing children, rapid bone growth requires sufficient Vitamin D to deposit calcium in the bone matrix. Step 3: When Vitamin D is deficient, bones remain poorly mineralised and become soft and easily deformed, leading to typical signs of rickets such as bowed legs and delayed closure of fontanelles. Step 4: Match rickets specifically with Vitamin D deficiency from standard nutrition tables. Step 5: Confirm that none of the other vitamins listed match the features of rickets. Step 6: Select Calciferol (Vitamin D) as the correct option.

Verification / Alternative check:
Nutrition and paediatrics textbooks clearly link rickets with childhood Vitamin D deficiency, often combined with inadequate calcium or lack of sunlight exposure. They describe how supplementation of Vitamin D and exposure to sunlight can prevent or treat rickets. In contrast, deficiency of Vitamin A causes night blindness, Vitamin B1 causes beriberi, Vitamin B12 affects the nervous system and red blood cell formation, and Vitamin C deficiency causes bleeding gums and poor wound healing. This clear mapping between nutrient and disease confirms the answer.

Why Other Options Are Wrong:
Carotene (provitamin A): Its deficiency causes night blindness and xerophthalmia, not rickets. Cyanocobalamin (Vitamin B12): Deficiency results in anaemia and neurological symptoms, not soft bones. Thiamine (Vitamin B1): Lack of this vitamin leads to beriberi with nerve and heart problems. Ascorbic acid (Vitamin C): Deficiency causes scurvy, characterised by bleeding gums and poor collagen formation, but not rickets.

Common Pitfalls:
Students sometimes confuse bone related diseases caused by Vitamin D deficiency (rickets in children, osteomalacia in adults) with Vitamin C deficiency, which affects connective tissue. Others may simply guess a vitamin without recalling the specific deficiency disease table. To avoid these errors, memorise key pairs such as Vitamin D with rickets, Vitamin C with scurvy, Vitamin B1 with beriberi, and Vitamin A with night blindness.

Final Answer:
The correct answer is Calciferol (Vitamin D).