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HUBS2207 > L13 B-Vitamins and One-Carbon Metabolism > Flashcards

L13 B-Vitamins and One-Carbon Metabolism Flashcards

1
Q

What is B1?

A

Thiamin

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2
Q

What is B2?

A

Riboflavin

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3
Q

What is B3?

A

Niacin

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4
Q

What is B5?

A

Pantothenic Acid

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5
Q

What is B6?

A

Pyridoxine

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6
Q

What is B7?

A

Biotin

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7
Q

What is B9?

A

Folate

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8
Q

What is B12?

A

Cobalamin

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9
Q

What is the natural form of folate also known as?

A

Polyglutamate

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10
Q

What is the synthetic form of folate?

A

Folic acid/monoglutamate

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11
Q

What form is folate in to be absorbed in the intestine?

A

Polyglutamate is hydrolysed to monoglutamate

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12
Q

How much folate is stored in the body and where is most of it?

A

11-28mg with 50% in the liver

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13
Q

What are two active forms of Cobalamin called?

A

Methylcobalamin and Adensylcobalamin

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14
Q

How much B12 is stored in the body and where is most of it?

A

2-4mg with 50% in the liver and 50% in other tissues

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15
Q

How is folate absorbed and activated?

A
  • Folate is eaten and broken into di- then monoglutamate
  • Methyl group is added to make 5-methyltetrahydrofolate, then it can be absorbed
  • Folate is trapped in an inactive form
  • B12 removes the methyl group, making both folate and B12 active. Active folate is tetrahydrofolate (THF)
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16
Q

What is an important function of THF?

A

Acts as a coenzyme in the transfer of one-carbon compounds such as methyl groups

17
Q

How is B12 digested and absorbed?

A
  • Pepsin and HCL get B12 from food
  • B12 binds to salivary (R) protein
  • Carried to the small intestine where B12 is released from R protein and bound to intrinsic factor (IF)
  • IF complex binds to receptors in the ileum where IF breaks down and B12 is bound to a transporter protein in the blood stream - Transcobalamin
18
Q

What is a main complication from folate deficiency?

A

Neural tube defects
- Anencephaly - brain doesn’t form properly
- Spina bifida - incomplete development of the spine

19
Q

What folate mandate did FSANZ implement in 2009?

A

Mandatory folate fortification of bread flour

20
Q

What is a complication of folate and/or B12 deficiency? And what are its symptoms?

A

Megoblastic Macrocytic Anaemia - production of abnormally large blood cells and less RBCs in circulation
Symptoms include fatigue, weakness, headaches, palpitations

21
Q

What are some causes of B12 deficiency? (3)

A
  • Malabsorption
  • Poor dietary intake
  • Surgical/post op
22
Q

What are some causes of folate deficiency? (4)

A
  • Poor dietary intake
  • Increased demand (e.g. pregnancy)
  • Malabsorption
  • Anti-folate drugs
23
Q

What is epigenetics?

A

The study of how your behaviors and environment can cause changes that affect the way your genes work

24
Q

What is the methyl-folate trap? What does this cause?

A

Without B12, 5-methyl THF cannot donate its methyl group to B12 which is how it becomes active
This causes a build up of homocysteine

25
Q

What are some adverse effects of hyperhomocysteinaemia? (5)

A
  • Damages blood vessels and degrades proteins
  • Risk factor for CVD and thrombosis
  • Role in Alzheimer’s disease
  • Pregnancy complications
  • Oxidative stress
26
Q

What one-carbon nutrients are involved in pregnancy? (5)

A
  • Folate (main)
  • B12 (main)
  • Methionine
  • Choline
  • B6
27
Q

Why are one-carbon nutrients important in pregnancy? (3)

A
  • Vital for epigenetic regulation of placenta and foetus
  • Enabling DNA synthesis
  • Required for optimal tissue growth and development
28
Q

What is homocysteine (Hcy)?

A

A thiol containing amino acid

29
Q

What are the two potential fates of homocysteine?

A
  • Recycled into methionine
  • Converted into cysteine
30
Q

What are some factors that may cause hyperhomocysteinaemia? (8)

A
  • Age
  • Male gender
  • Menopause
  • Smoking
  • High coffee consumption
  • Low consumption of fruits and vegetables
  • Diabetes
  • Some drugs

HUBS2207 (7 decks)

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