Nutrition: vitamin B12 deficiency in vegetarians: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Nutrition: vitamin B12 deficiency in vegetarians

Sample item

A 35-year-old strict vegan has a macrocytic anaemia, tingling of the feet and a smooth tongue. Which dietary deficiency is most likely?

ARiboflavinBVitamin B12CNiacinDVitamin C

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Vitamin B12

Vitamin B12 is found almost only in animal foods, so strict vegetarians who avoid milk and eggs are at risk. Deficiency causes megaloblastic anaemia and subacute combined degeneration of the cord. Stores last for years, so symptoms develop slowly.

Option by option

A. Riboflavin
Riboflavin deficiency causes angular stomatitis and glossitis, usually without neuropathy.
B. Vitamin B12 (correct)
Correct. Vitamin B12 is absent from plant foods and deficiency causes macrocytic anaemia with neuropathy.
C. Niacin
Niacin deficiency causes pellagra with dermatitis, diarrhoea and dementia.
D. Vitamin C
Vitamin C deficiency causes scurvy with bleeding gums and does not cause macrocytic anaemia.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, Vitamin B12. Vitamin B12 is found almost only in animal foods, so strict vegetarians who avoid milk and eggs are at risk.

Why is "Riboflavin" not the answer?

Riboflavin deficiency causes angular stomatitis and glossitis, usually without neuropathy.

Why is "Niacin" not the answer?

Niacin deficiency causes pellagra with dermatitis, diarrhoea and dementia.

Why is "Vitamin C" not the answer?

Vitamin C deficiency causes scurvy with bleeding gums and does not cause macrocytic anaemia.

What concept does this question test?

It tests Nutrition: vitamin B12 deficiency in vegetarians in PSM. Deficiency causes megaloblastic anaemia and subacute combined degeneration of the cord. Stores last for years, so symptoms develop slowly.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Nutrition: vitamin B12 deficiency in vegetarians?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.