Vitamins

Q: Vitamin B12 absorption:

Depends on the presence of intrinsic factor. Depends on the presence of intrinsic factor is the physiologically correct answer per standard MBChB-level teaching on this topic. ---

Q: Vitamin C is absorbed from the small intestine by:

Passive diffusion. Na⁺-dependent secondary active transport is the physiologically correct answer per standard MBChB-level teaching on this topic. ---

Q: Vitamin B12 is absorbed via:

Simple diffusion. Endocytosis is the physiologically correct answer per standard MBChB-level teaching on this topic. ---

What our notes say

| Warfarin | Vitamin K antagonist | When DOACs are unavailable: INR 2–3 | Bleeding; many interactions; teratogenic | (DVT and Venous Thromboembolism (with Pulmonary Embolism))
Fat-soluble vitamins are malabsorbed, not vitamins B and C. (Paediatrics end of 2nd semester exam (MBPE 4300): 5 October 2021, 50 MCQs)
Give vitamin K if not given, start expressed breast milk by nasogastric tube as soon as she is stable, and support the mother. (Integrated case paper: Medicine, Surgery, Gynaecology and Paediatrics (160 marks)
This is vitamin B12 deficiency with hypersegmented neutrophils. (Internal Medicine End of Semester CAT (MBChB 4): haematology and renal, 30 MCQs )
Vitamin C is converted to oxalate, so it raises oxalate excretion. (Internal Medicine End of Semester CAT (MBChB 4): haematology and renal, 30 MCQs )
A nutritious diet and vitamins (especially B vitamins) are important during the first days of abstinence. (Internal Medicine CAT 1 (MBChB 4), 2022: liver, pancreas and bone marrow, 30 MCQ)

Study material on Vitamins

Images

Clinical photo of a large fluctuant swelling over the lower spine

Practice questions on Vitamins

Vitamin B12 absorption:

Depends on the presence of intrinsic factor
Depends on passive diffusion
Occurs in the jejunum
Occurs in the stomach ✅ Answer: A. Depends on the presence of intrinsic factor

Answer: A. Depends on the presence of intrinsic factor is the physiologically correct answer per standard MBChB-level teaching on this topic. ---

Vitamin C is absorbed from the small intestine by:

Passive diffusion
Na⁺-dependent secondary active transport
Primary active transport
Facilitated diffusion ✅ Answer: B. Na⁺-dependent secondary active transport

Answer: A. Na⁺-dependent secondary active transport is the physiologically correct answer per standard MBChB-level teaching on this topic. ---

Vitamin B12 is absorbed via:

Simple diffusion
Endocytosis
Osmosis
Exocytosis ✅ Answer: B. Endocytosis

Answer: A. Endocytosis is the physiologically correct answer per standard MBChB-level teaching on this topic. ---

The following are correct about vitamin B12 EXCEPT

it is also called cobalamin
it is required in hydroxylation reactions
one of its structural components is a corrin ring
it is important in the catabolism of some branched chain amino acids
its methyl derivative is required in the synthesis of methionine ✅ Answer: B. it is required in hydroxylation reactions

Answer: A. This is the false statement (as asked): vitamin B12 (cobalamin) participates in methylmalonyl-CoA mutase and methionine synthase reactions (isomerization and methyl transfer), not hydroxylation reactions. ---

Lack of vitamin C leads to

well deposited collagen
Membrane lipid peroxidation
Beriberi
High amounts of hydroxyproline
Scurvy ✅ Answer: E. Scurvy

Answer: A. Vitamin C deficiency causes scurvy — impaired collagen hydroxylation leads to fragile connective tissue, bleeding gums, and poor wound healing. ---

The vitamin A derivative that plays a role in vision is;

All trans-retinal
Retinoic acid
11-cis retinal
β-carotene
All trans-retinol (A1) ✅ Answer: C. 11-cis retinal

Answer: A. 11-cis-retinal is the vitamin A derivative that combines with opsin to form rhodopsin and directly mediates the light-triggered visual response. ---