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Metabolism Block > Vitamins > Flashcards

Vitamins Flashcards

1
Q

Discuss the nutritional value of Thiamin (B1)

A

Biological role

  • coenzyme in decarboxylations - particularly pyruvate to acetyl CoA (all energy derived from aerobic metabolism is dependent on thiamin availabilty
  • carbohydrate, protein and fat metabolism
  • nerve function

**Food sources **

  • Vegemite
  • Soba Noodles
  • wholemeal breads and fortified cereals

Deficiency

  • Rapid depletion in starvation.
  • Beriberi
  • Wernicke-Korsakoff syndrome in alcoholics
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2
Q

What is Beriberi?

A

_Beriberi is a thiamine deficiency that results in extreme weakness, paralysis, anaemia
and wasting._

When serum albumin is low
the resulting oedema gives the diagnosis
“wet” beriberi.

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3
Q

What is Wernicke Korsakoff Syndrome?

A

WKS affects 2% of Australians and is the most common cause of thiamin deficiency in
Australia (and of any vitamin deficiency). The deficiency develops through bad nutrition (little fruit and veg) and alcohol metabolism destroying thiamine

Symptoms: eyes uncoordinated (nystagmus), wide step, confusion, hypothermia, amnesia and confabulation.

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4
Q

Discuss the nutritional value of Riboflavin

A

Biological role

  • electron carrier (FMN, FAD)
  • carbohydrate, protein and fat metabolism

**Food sources **

  • Vegemite
  • Milk/cheese
  • Fortified cereals

Deficiency

  • rare (chronic alcoholics)
  • usually associated with multiple vitamin deficiencies
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5
Q

What vitamin deficiency is associated with a magenta tongue?

A

A magenta tongue is common in riboflavin deficiencies,

Main complaint is of a very sore tongue, which is seen to be markedly swollen and
oedematous and to have a light magenta colour

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6
Q

Discuss the nutritional value of Niacin (B3)

A

Biological role

  • Coenzyme
  • electron carrier (NADH, NADPH)
  • carbohydrate, protein and fat metabolism

Food sources

  • Vegemite
  • wheat bran
  • fortified cereals

Deficiency

  • alcoholics
  • Pellagra (dermatitis, diarrhoea, dementia, death)
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7
Q

Discuss the nutritional value of Vitamin B6 (pyridoxine)

A

Biological role

  • amino acid metabolism

**Food sources **

  • Vegemite
  • nuts
  • bananas
  • fortified cereals

Deficiency

  • rare
  • need varies with protein intake
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8
Q

Discuss the nutritional importance of Biotin

A

Biological role

  • Adding CO2
  • glucose, fat and amino acid biosynthesis

Food sources

  • brewer’s yeast
  • egg yolk (cooked)
  • soy beans

Deficiency

  • people who eats large amounts of raw eggs
    • raw eggs contain avidin that antagonises the action of biotin
    • patients with deficiencies have hand skin that is shiny dry and scaly.
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9
Q

Discuss the nutritional value of folate

A

Biological role

  • ‘one carbon’ metabolism (amino acids,
  • fat, purines for DNA)

Food sources

  • Green vegetables, liver
  • fortified cereals

Deficiency

  • common in elderly, chronic alcoholics
  • a concern for pregnant women
  • macrocytic anemia (large RBC)
  • neural tube defects (spina bifida).
  • Folic acid deficiency can cause glossitis: the tongue becomes very red and painful and the papillae atrophy, leaving a shiny, smooth surface.
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10
Q

Discuss the nutritional value of Vitamin B12

A

Biological role

  • coenzyme containing cobalt
  • folate metabolism; transalkylations.

Food sources

  • Meat, egg yolks, cheese

Deficiency

  • rare, but a concern for vegetarians, particularly vegans
  • neurological disorders and pernicious anaemia
    • accompanies a pronounced lemon-yellow tinge + faint icterus of sclerae due hyperbilirubinaemia
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11
Q

What is the significance of Intrinsic Factor in nutrition?

A

Intrinsic factor is a glycoportein produced by parietal cells of the stomach.

It is a necessary for the absorbtion of vitamin B12 in the small intestine

Autoantibodies/damage directed against intrinsic factor or parietal cells lead to pernicious anaemia

Deficiencies in intrinsic factor are treated with B12 injections

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12
Q

What is the nutritional value of Vitamin C

A

Biological role

  • cofactor in collagen synthesis
  • neurotransmitter metabolism
  • iron absorption
  • antioxidant

**Food sources **

  • citrus fruits
  • cabbage

Deficiency

  • scurvy
    • Vitamin C is required for the synthesis of collagen -> deficiencies prevent this. Most notably lose teeth due to gum disease
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13
Q

Discuss the nutritional value of Vitamin A

A

Vitamin A is a group of nutritional organic compounds that are derived from beta-carotene; they include retinol, retinal and retinoic acid

Biological Role

  • Retinal important in night vision
  • Retinol important in epithelium growth (healthy skin and eyes)
  • Is toxic in high amounts
  • Stored in liver

Food sources

  • Meat
  • Bananas

**Deficiencies **

  • Xerophthalmia
    • Orange bananas trialling with 5x amount vitamin A for African, Asian and South American populations where vit A deficiencies are endemic
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14
Q

Discuss the nutritional value of Vitamin D

A

Vitamin D isn’t technically a vitamin because we can make it

It is derived from cholesterol but needs UV light for synthesis

Biological Function

  • Ca2+regulation
  • Bone development

Food Sources

  • Dairy products
  • Leafy green vegetables
  • Soy and Tofu

Deficiencies

  • Rickets disease
    • know knee and bow leg children due to abnormal bone development
  • Osteomalacia
    • defective bone mineralisation secondary to inadequate calcium
  • At least 1,000 genes are affected by vitamin D and some mediate protection against infection, cancer and autoimmune diseases.
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15
Q

Illustrate the regulatory mechanism of Ca2+

A
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16
Q

Discuss the nutritional value of Vitamin E

A

Vitamin E is an antioxidant.

Inserts in membranes and intercepts free radicals

Signal molecule linked to inflammation and cell division (newly found functions).

Suggests caution in taking vitamin E pills.

Found in high levels in seed oils

Evidence is accumulating that supplements increase lung cancer and heart disease. Vitamin-A supplements are significantly dangerous for smokers. Free radicals are not always bad

17
Q

Discuss the nutritional value of vitamin K

A

Vitamin K is important in blood clotting

prothrombin + vitamin K → carboxy-glutamate at active site

Activated thrombin causes fibrinogen to convert to fibrin and form a blood clot. Inadequate clotting leads to haemorrhage.

Gut flora make significant vitamin K.

Haemorrhagic disease of the newborn (sterile gut) is avoided by giving an injection to newborns. Also known as vitamin K deficiency bleeding (VKDB) of the newborn.

18
Q
A

Metabolism Block (9 decks)

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