Deficiency of niacin, a vitamin of the B complex group also known as vitamin B3, causes which of the following human deficiency diseases?

Introduction / Context:
Vitamins are essential micronutrients that play key roles in metabolism and health. Deficiency of a particular vitamin leads to characteristic deficiency diseases. Niacin, also called vitamin B3, is part of the B complex group and is important for energy metabolism and proper functioning of the nervous system and skin. This question asks you to identify which deficiency disease results specifically from a lack of niacin in the diet.

Given Data / Assumptions:

• The vitamin mentioned is niacin, a member of the B complex vitamins and also known as vitamin B3.

• Several well known deficiency diseases are listed, including marasmus, pellagra, rickets, night blindness, and goitre.

• We assume familiarity with which vitamin deficiencies are linked to each disease.

• Only one of the diseases given is classically associated with niacin deficiency.

Concept / Approach:
Niacin functions as part of coenzymes involved in oxidation reduction reactions in the body, notably NAD and NADP. Deficiency of niacin leads to pellagra, a disease historically described by the triad of dermatitis, diarrhoea, and dementia, sometimes summarised as the three Ds. Marasmus is due to severe protein energy malnutrition, rickets is due to vitamin D deficiency, night blindness is due to vitamin A deficiency, and goitre is related to iodine deficiency affecting thyroid hormone production. Therefore, the correct matching of vitamin B3 deficiency is with pellagra.

Step-by-Step Solution:
Step 1: Recall that niacin is vitamin B3 and is essential for proper functioning of enzymes involved in energy metabolism. Step 2: Understand that a severe deficiency of niacin or its precursor tryptophan results in pellagra. Step 3: Recognise the classical symptoms of pellagra, including rough, scaly skin exposed to sunlight, diarrhoea, and mental changes. Step 4: Consider marasmus, which arises from overall protein calorie malnutrition in children, not specifically a single vitamin deficiency. Step 5: Note that rickets is associated with a deficiency of vitamin D, calcium, or phosphate leading to soft and deformed bones in children. Step 6: Recall that night blindness is classically linked to vitamin A deficiency, which impairs the formation of visual pigments. Step 7: Recognise that goitre is usually due to iodine deficiency or thyroid problems and is not caused by lack of niacin. Step 8: Thus, the only disease in the list specifically linked to niacin deficiency is pellagra.

Verification / Alternative check:
Nutrition and medical references consistently list pellagra under vitamin B3 or niacin deficiency. Tables of vitamins and their deficiency diseases show this one to one relationship. Historical accounts of pellagra outbreaks in populations relying heavily on untreated maize, which is low in available niacin, further strengthen the association between niacin deficiency and pellagra. In contrast, marasmus, rickets, night blindness, and goitre are placed in sections on protein energy malnutrition, vitamin D deficiency, vitamin A deficiency, and iodine deficiency respectively, confirming that they do not result from niacin lack.

Why Other Options Are Wrong:

Marasmus: Caused by severe deficiency of calories and protein, not specifically by niacin deficiency.

Rickets: Due to vitamin D deficiency and impaired bone mineralisation in children.

Night blindness: Typically associated with vitamin A deficiency affecting vision, especially in low light.

Goitre: Mainly linked to iodine deficiency and thyroid gland enlargement, not to niacin.

Common Pitfalls:
Students sometimes mix up the deficiency diseases of B complex vitamins because there are many of them and the names can be confusing. Another pitfall is assuming that any disease with skin symptoms must be related to vitamin A, when pellagra also affects skin. A good strategy is to memorise key pairs, such as niacin and pellagra, thiamine and beriberi, and vitamin C and scurvy, to quickly answer such questions.

Final Answer:
Deficiency of niacin vitamin B3 causes the disease Pellagra.