Vitamin B1

Question 1

The active form of vitamin B1 (thiamine) is ______________________.

Answer 1

thiamine pyrophosphate (TPP).

Question 2

State the sources of vitamin B1.

Answer 2

Whole grain, wheat germ, meat, eggs, beans, peanuts.

Question 3

State the roles of vitamin B1.

Answer 3

• TPP transfers aldehyde groups.
• Pyruvate dehydrogenase and α- ketoglutarate dehydrogenase play crucial roles in carbohydrate metabolism and utilize TPP as a cofactor. The two complexes are similar in mechanism of reaction.
• Transketolase reactions in hexose monophosphate (HMP) shunt (pentose phosphate pathway) require TPP.
• Pyruvate decarboxylase in alcoholic fermentation of sugar by yeast requires thiamine.

Question 4

Outline the deficiency effects of vitamin B1.

Answer 4

• Moderately severe thiamine deficiency causes Wernicke-Korsakoff syndrome characterized by:
  Mental confusion, ataxia (unsteady gait and inability to achieve fine control of motor functions), ophthalmoplegia (loss of eye coordination). [Does it remind you of neuroanatomy? 😁]
• Severe thiamine deficiency causes beriberi, a neurologic and cardiovascular disorder.

NB: Polished rice exacerbates the problem because only the husks contain significant amounts of thiamine.

Question 5

What is different between dry and wet beriberi in terms of who it affects?

Answer 5

• Dry beriberi affects alcoholics because heavy alcohol consumption causes malabsorption of thiamine.
• Wet beriberi affects infants and is characterized by neurological disorders and oedema.