Intestinal bacteria are main source of which one of the following vitamins?
- (a)Vitamin E
- (b)Vitamin C
- (c)Vitamin B₁₂
- (d)Vitamin A
Correct — C, Vitamin B₁₂. The bacteria that live in the human large intestine synthesise several vitamins, including vitamin B₁₂ (cobalamin) and vitamin K. Of the four options, only vitamin B₁₂ is one that gut bacteria produce; vitamins A, C and E are obtained from the diet, not made by intestinal bacteria. So the correct choice is vitamin B₁₂.
- (a)Vitamin E — Vitamin E (tocopherol) is a fat-soluble vitamin taken in through the diet (vegetable oils, nuts, seeds); it is not synthesised by intestinal bacteria.
- (b)Vitamin C — Vitamin C (ascorbic acid) must come from the diet — fruits and vegetables — because neither the human body nor its gut bacteria supply it.
- (d)Vitamin A — Vitamin A (retinol) comes from the diet, as retinol from animal foods or as beta-carotene from plants; gut bacteria are not its source.
The human gut, especially the large intestine, hosts a large community of bacteria (the gut microflora). Besides helping digestion, these microbes synthesise certain vitamins — notably vitamin K and several B-complex vitamins including B₁₂ (cobalamin), biotin and folate. This is why intestinal bacteria are named as a source of vitamin B₁₂ among the options, whereas the fat-soluble vitamins A and E and the water-soluble vitamin C are supplied by food.
Sort the vitamins by origin: A, C and E are dietary, while B₁₂ (and K) are made by gut bacteria. Only vitamin B₁₂ appears in the options as a microbially made vitamin, so it is the answer.
- Gut bacteria in the large intestine synthesise vitamin K and B-complex vitamins including B₁₂ (cobalamin).
- Vitamins A, C and E must be obtained from the diet.
- Vitamin B₁₂ is essential for red blood cell formation and nerve function.
- Vitamin C deficiency causes scurvy and vitamin A deficiency causes night blindness — reminders that these are dietary.
Only vitamin B₁₂ is made by intestinal bacteria — so the answer is (c).
- Assuming a dietary vitamin (A, C or E) is the answer — only B₁₂ is made by gut bacteria here.
- Forgetting that gut bacteria also make vitamin K, which was not one of the options.
Asked as which vitamin intestinal bacteria supply — recall that gut microbes make vitamin B₁₂ (and K), while A, C and E are dietary.
No directly related past PYQ was found.
- practice — not a real PYQ
Deficiency of vitamin B₁₂ mainly leads to
- (a)Scurvy
- (b)Anaemia
- (c)Night blindness
- (d)Rickets
Answer(b) Anaemia — vitamin B₁₂ is needed for red blood cell formation (pernicious anaemia).
- practice — not a real PYQ
Which vitamin, also synthesised by intestinal bacteria, is essential for the clotting of blood?
- (a)Vitamin A
- (b)Vitamin C
- (c)Vitamin K
- (d)Vitamin D
Answer(c) Vitamin K — needed for the clotting of blood.