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Nutritional Physiology > Water Soluble Vitamins > Flashcards

Water Soluble Vitamins Flashcards

1
Q

B group Vitamins involved in energy metabolism?

A
  • Thiamin (B1)
  • Riboflavin (B2)
  • Niacin (B3)
  • Pantothenic Acid
  • Biotin
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2
Q

Thiamin

Thiamin Role

A
  • Central role in generation of energy from carbohydrates
  • nerve function
  • transported by RBCs
  • excess quickly excreted in the urine
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3
Q

Thiamin

Active form of Thiamin as a coenzyme

A

Thiamin Pyrophosphate (TPP)

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4
Q

Thiamin

Coenzyme: Thiamin Pyrophospate (TPP)

A

Converts pyruvate to acetyl CoA

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5
Q

Thiamin

Deficiency of Thiamin

A

Wet Beriberi and Dry Beriberi

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6
Q

Thiamin

Wet Beriberi

A

Oedema (swelling), enlarged heart, heart failure
* Results from accumulation of pyruvate and lactate
* Generally seen in active individuals due to increased glycolysis

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7
Q

Thiamin

Dry Beriberi

A

Weakness, nerve degeneration, poor arm/leg coordination

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8
Q

Thiamin

Wernicke-Korsakoff Syndrome

A

Seen mainly in alcoholics because:
* Alcohol diminishes thiamin absorption
* Alcohol increases thiamin excretion

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9
Q

Thiamin

  1. Wernicke’s Encephalopathy (WE)
A
  • Nystagmus: involuntary eye movement; double vision
  • Ataxia: staggering, poor muscle coordination; mental confusion
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10
Q

Thiamin

  1. Korsakoff’s psychosis (KP)
A

Confusion and loss of memory

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11
Q

Thiamin

Food Sources of Thiamin

A

Bread and cereals (wholegrain or enriched), wheat germ, yeast, legumes, nuts, pork, soy milk

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12
Q

Riboflavin

Riboflavin Role

A

Involved in energy production in (notably for release of energy from nutrients in all cell bodies):
* Electron transport chain
* Citric acid cycle
* Catabolism of fatty acids

Important role in the oxidation pathways
* important in preventing damage to cells by free radicals

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13
Q

Riboflavin

Coenzymes of Riboflavin

A
  • Flavin adenine dinucleotide (FAD)
  • Flavin mononucleotide (FMN)
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14
Q

Riboflavin

Deficiency of Riboflavin - Ariboflavinosis

A

Ariboflavinosis
* Glossitis (inflamed tongue)
* Cheilosis (cracked lips)
* Stomatitis (inflammation of mucus in mouth)
* Alopecia (hair loss)
* Dermatitis

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15
Q

Riboflavin

Food sources of riboflavin

A

Dairy products such as milk and milk products (greatest
contributions)
* Wholegrains

  • Sensitive to UV radiation (sunlight) - stored in paper or
    opaque plastic containers
  • Stable to heat, so cooking does not destroy
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16
Q

Niacin

Niacin Role

A

‘Niacin’ describes two chemical structure: nicotinic acid (niacin) and nicotinamide found equally in food.

Oxidation-reduction reactions to produce energy:
* Glycolysis
* Electron transport chain
* etc.

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17
Q

Niacin

Coenzymes of Niacin

A
  • Nicotinamide adenine dinucleotide (NAD)
  • Nicotinamide adenine dinucleotide phosphate (NADP)
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18
Q

Niacin

Transportation and storage of Niacin

A

Transported from the liver to all the tissues where it is converted to the coenzymes
* Niacin can also be produced endogenously from tryptophan (essential amino acid)

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19
Q

Niacin

Deficiency of Niacin

A

The ‘4 Ds’ of Pellagra or niacin deficiency

20
Q

Niacin

Pellagra

A
  1. Dermatitis
  2. Dementia
  3. Diarrhoea
  4. Death
21
Q

Niacin

Food Sources of Niacin

A

Eggs, meat, poultry and fish – protein rich foods
* Liver
* Mushrooms
* Whole-grain and enriched breads and cereals
* Nuts and all protein-containing foods
* Heat stable; little cooking loss

22
Q

Pantothenic Acid

Pantothenic Acid Role

A

Part of coenzyme A (CoA)
* Essential for metabolism of CHO, fat, protein

23
Q

Biotin

Biotin Role and Deficiency

A
  • Metabolism of CHO, fat, and protein via carboxylase reactions (addition of CO2)
  • Deficiency rare as found in most foods (can also be produced by GI bacteria)
24
Q

Biotin

Toxicity of Biotin

A
  • No toxicity level reported
  • Avidin (found in egg whites ) inhibits absorption
  • More than a dozen raw eggs a day to cause this effect
25
Q

Vitamin B6 (Pyridoxal, Pyridoxine,
Pyridoxamine)

A

Vitamin B6 is involved in the transamination and
deamination process.
* Synthesis of haemoglobin
* Niacin synthesis (from tryptophan)
* Synthesis of neurotransmitters (serotonin, dopamine,
histamine and GABA)

26
Q

Coenzyme form of Vitamin B6

A

Pyridoxal Phosphate (PLP) - active in amino acid metabolism

27
Q

Deficiency of Vitamin B6

A
  • depression, confusion
  • Anaemia
  • Dermatitis (related to niacin deficiency)
  • Reduced immune response
  • Peripheral nerve damage
27
Q

Food Sources of Vitamin B6

A
  • Meat, fish, poultry
  • Whole grains
  • Bananas
  • Spinach
  • Avocados
  • Potatoes
  • Heat and alkaline sensitive* - foods lose vitamin B6 when heated
28
Q

Alternative names for Folate

A

Folic Acid or Folacin

29
Q

Coenzyme form of Folate

A

Tetrahydrofolate (THF) – helps synthesis of DNA for rapidly growing cells

30
Q

In what form do foods moslty deliver folate in?

A

Foods mostly deliver folate in the ‘bound’ form – known as polyglutamate

31
Q

How is folate absorbed?

A

Small intestine prefers to absorb ‘free’ folate form instead of ‘bound’ form (i.e., free contains only one glutamate attached)
* Enzymes on the intestinal cells breaks glutamates off and adds a methyl group. Folate in this form (with methyl, NH3) can be absorbed and delivered to cells
* However, in the cells, methyl groups must be removed in order to function
* Therefore, to activate this, vitamin B12 removes the methyl group

32
Q

Difference between Folate and Folic Acid

A
  1. Folate is the form found in food and represents the various biochemical forms of pteroyl glutamic acid (folicin; vitamin M; vitamin B9)
  2. Folic acid is the synthetic form of folate and used extensively in dietary supplements and food fortification (does not occur naturally in significant amounts)
33
Q

Deficiency of Folate

A
  • seen in late pregnancy, malabsorption syndromes and alcoholics

Results in:
* Megaloblastic anaemia (immature RBCs lose ability to divide from impaired DNA synthesis)
* Absorption problems (from immature intestinal cells)- GI tract deterioration
* Neural tube defects (NTDs)

34
Q

Food Sources of Folate

A

Bread (~140 µg/serve)
* Fortified breakfast cereals
* Grains, legumes (lentils, pinto beans)
* Green, leafy vegetables
Susceptible to heat, oxidation, ultraviolet light

35
Q

Vitamin B12 Role

A

Closely related to folate: each depends on the other for activation
* Removal of methyl group to active the folate coenzyme
* Involved in the metabolism of folate

36
Q

Deficiency of Vitamin b12

A

Pernicious anaemia
Clinically looks like folate deficiency (megaloblastic)
* Nerve degeneration, weakness
* Tingling/numbness in the extremities (parasthesia)
* Paralysis and death

37
Q

Food Sources of Vitamin b12

A

Synthesised by bacteria
* Animal products
* Organ meat
* Seafood
* Eggs, Milk
* Fortified soy
* Easily destroyed by microwave cooking*

38
Q

B-group food sources: summary

A
  • Grains provides thiamin, riboflavin, niacin and folate
  • Fruits and vegetables provide folate
  • Meat group provides thiamin, niacin, vitamin B6 and vitamin B12
  • Milk group provides riboflavin and vitamin B12
39
Q

Vitamin C

A

Ascorbic acid (reduced form),
dehydroascorbic acid (oxidised form)
* Synthesised by most animals (not by
humans)
* Passive transport if intake is high
* Excess excreted

40
Q

Functions of Vitamin C

A
  • Reducing agent (antioxidant)
  • Immune functions
  • Increase Iron absorption
  • Converts Fe3+ to Fe2+ (more absorbable)
  • Collagen synthesis – form fibrous structural protein
    of tissues
41
Q

Deficiency of Vitamin C

A

Scurcy and Rebound Scurvy

42
Q

Scurvy

A
  • Fatigue, pinpoint haemorrhages
  • Bleeding gums and joints
43
Q

Rebound Scurvy

A

Seen rarely with immediate halting of megadose vitamin C supplements

44
Q

Food Sources of Vitamin C

A
  • Citrus fruits
  • Green and red capsicums
  • Cauliflower/Broccoli
  • Strawberries
  • Spinach
  • Kiwi fruit
  • easily lost through cooking
  • sensitive to heat
  • sensitive to iron, copper and oxygen
45
Q

Vitamin C toxicity

A

Toxicity Symptoms:
* Nausea, abdominal cramps, diarrhoea, headache, fatigue and insomnia
* Hot flashes and rashes
* Aggravation of gout symptoms, urinary tract infections and kidney stones
* In those with iron overload diseases (haemochromatosis)

Nutritional Physiology (5 decks)

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