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Human nutrition and physiology > Water soluble vitamins > Flashcards

Water soluble vitamins Flashcards

1
Q

Where is thiamine stored in the body?

A

Half of the thiamine in the body is in muscles. There is high thiamine in liver and kidneys

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2
Q

In what forms does Thiamine (B1) exist in food?

A

in free form, diphosphate, or bounded to proteins

• Thiamine is absorbed in upper part of small intestine

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3
Q

Absorption of thiamine?

A

Absorbed small intestines

Some can be made by GM

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4
Q

What is an important role of Thiamine (B1)?

A
  • co-factor for pyruvate dehydrogenase and α-ketoglutarate
    dehydrogenase
  • also important for activity of transketolase in biosynthesis of ribose
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5
Q

What causes beriberi?

A

Long term thiamine deficiency

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6
Q

What is beriberi associated with?

A

Disturbance in nerve system

divided into dry and wet

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7
Q

What can decrease Thiamine uptake?

A

Alcohol and metication

alcohol also produce more urine and therefore more thiamine is excreted

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8
Q

What is mostly effected by lack of Thiamine?

A

Organs depending most in carbohydrate metabolism

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9
Q

Sources of thiamine?

A

Meat, peas and beans

In sweden cereal products most important

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10
Q

Sources of riboflavin (B2)?

A

Different animal and food products. (more in animal)

ex. milk products main source in sweden

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11
Q

Riboflavin is sensitive to what?

A

Basic condition and light

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12
Q

Absorption of niacin (B3 or B5)

A

Absorbed in upper part of small intestine
- in cereal products is bounded to a protein and should be released before in order to be absorbed
Can also be synthesized by the gut microbiota

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13
Q

In what way does Niacin exist in all cells?

A

in the form of co-enzymes
is used in biosynthesis of NAD and NADP
which are important for central carbon and energy metabolism

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14
Q

What causes pallagra?

A

Niacin deficiency

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15
Q

In what form does riboflavin usually occur?

A

Apart of FAD

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16
Q

Why is riboflavin important?

A

Riboflavin is central for the energiproduction of the cells and is needed for carbohydrate-, fat- and proteindigestion

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17
Q

Niacin can be made from what?

A

Tryptophan

3 other B vitamins also necessary then

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18
Q

Why do you need to eat more Niacin when you are physicaly active?

A

Since niacin is important for energy metabolism

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19
Q

Pyridoxine (B6) exist is several form ex…

A

Pyridoxine
Pyridoxal
Pyridoxamine

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20
Q

Who does Pyridoxine (B6) exist in the body?

A

In free and phosphate forms

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21
Q

What happens to the phosphorylated forms?

B6

A

They are broken down during cooking and digestion

then rephosphorylated

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22
Q

What is pyridoxine involved in?

A

Mainly involved in transamination and decarboxylation of amino acids
- also involved in reaction to break down glycogen

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23
Q

Pyridoxine in body is related to what?

A

protein intake

24
Q

What is the relationship between B6 and alpha-ketoglutarate ?

A

Pyridoxine alpha ketoglutarate (PAK) is a combination of Vitamin B-6 and alpha ketoglutarate. In the liver it is converted to pyridoxal phosphate - the biologically active form of B-6. This acts as a coenzyme in the metabolism of protein, carbohydrates, and fats.

25
Q

What does alpha-ketoglutarate do

A

The NADH can enter into the mitochondria and be converted to ATP

26
Q

Pyridoxine is sensitive to what? and what can have during food processing?

A

sensitive towards light, oxygen and basic conditions.
during food processing can react with cysteine in food and get inactivated
- there are several B6-antagonists that can prevent biological activity

27
Q

Which vitamin can cause neurological symptoms when consumed in high doses?

A

Pyridoxine

28
Q

Where does biotin exist in the body?

A

In tissues it is bound with a protein

As a cofactor in enzyme participating in carboxylation

29
Q

Why not eat raw egg white if you want to take up biotin`?

A

Egg white has a glycoprotein that can bpund to biotin and prevent its absorption. However it is denatured when cooked so then it is ok!

30
Q

Do we need alot of biotin through diet?

A

No!
It is one of the most active vitamins in the body so just need very low concentrations.
A part also made by the gut microbiota

31
Q

Function of biotin

A

Biotin is a cofactor responsible for carbon dioxide transfer in several carboxylase enzymes:

Biotin is important in fatty acid synthesis, branched-chain amino acid catabolism, and gluconeogenesis.

32
Q

Why is pantothenic acid necessary for any kind of energy production in the body?

A

Because it is an important part of coenzyme A (CoA)

And important in acyl transfer. Making sure Acetyl CoA goes into krebs cycle

33
Q

Foods rich in Panthothenic acid and absorption?

A

Animal products, whole grain, peas and beans are rich sources.
Thought to be absorbed passively

34
Q

Ascorbic acid can easily be oxidized to dehydroascorbic acid, what could happen then?

A

Dehydroascorbic acid is unstable and can be converted to 2,3-Diketogulonic which does not have vitamin C effect and cannot be converted back to vitamin C

35
Q

How is the absorption of ascorbic acids ?

A

Active way in small intestine

36
Q

What need more vitamin c?

A

Organs with high metabolic rate.

Highest is in the adrenals

37
Q

A few ways ascorbic acid is important

A
  • important role in hydroxylases e.g. conversion of proline to hydroxyproline
  • can increase ironabsorption by reducing Fe3+ to Fe2+
38
Q

Vit C is sensitivee to what?

A

heat and oxidation

39
Q

How many forms of folate are there that have different functions in the body?

A

Three
THF - carbon carrier (natural in food)
5,10-methylene-THF
5-methyl- THF

40
Q

The 1C metabolic pathway involves a set of reactions that generate and transfer activated one carbon (1C) units for de novo nucleotide synthesis, compartmentalize amino acids, and contribute to redox homeostasis.
What is the fole of THF

A 
The co-factor tetrahydrofolate (THF) is the carrier that mediates 1C transfer reactions for de novo nucleotide synthesis.
Catabolizes serine (3C) (to generate glycine(2C)) in the mitochondria and synthesizes serine in the cytosol.
41
Q

How are folate and b12 connected?

A

Both part in converting homocystein to metionin

if high homocystein values docotor will give you both vitamins

42
Q

Absorption of folate

A

Absorbed upper part pf intestine
In intestine glutamate chain is released. So just mono-glutamated form enters blood
Absorption varies between 40-90% depending on the food and folate.

43
Q

Folate involved in which metabolisms?

A

Amino acid
purine
pyrimidine

44
Q

Lack of folate can cause

A

problem with cell division and protein metabolism

increase homocysteine levels (riskfactor for CVD)

45
Q

Absorption of cobalamin (B12)

A 
Needs a (inner factor) glycoprotein which is produced in the stomach.
Joining vitamin and protein helps vitamin to bind to a receptor in lower part of intestine for absorption. 
- Vitamin absorbed in intestinal cells is then delivered to a protein which is carrying vitamin molecule in the blood.
- Considereing mechanism of absorption, dividing intake to several portions increase absorption
46
Q

Where is cobalamin stored?

A

Liver

47
Q

In which reactions are cobalamin (B12) important?

A 
Cobalamin is important for reactions including transferring methyl group in connection
with folate (e.g. homocysteine, conversion of ethanolamine to choline)
48
Q

Methionine - Homocycteine cycle

role of b12

A
  • MTHF gives carbon to B12 – which give carbon to homocysteine and produce methionine
    methionine activated to S-adenosylmethionine (SAM)
49
Q

B12 is coenzyme to which enzyme in which reaction?

A

Mutase

catalysis of methylmalonyl CoA to succinyl CoA.

50
Q

Which vitamin is important for the activity of
transketolase
and cofactor of pyruvate dehydrogenase and alpha-ketoglutarate

A

Thiamine B1

51
Q

Riboflavin exists to a higher degree in what organs?

A

Liver and kidney

52
Q

Important about riboflavin

A

important in electron transfer ex. FAD

53
Q

Which vitamin is cofactor in all cells, used in biosynthesis of NAD and NADP

A

Niacin (B3)

54
Q

What can cause pellagra?

A

Niacin deficiency

55
Q

Main role of pyridoxine

A

Mainly involved in transamination and decarboxylasion of amino acids

Transamination is when move amino group to keto acid to form new amino acid

56
Q

Pyridoxine’s relation to electon transport chain

A

Malate-aspartate shuttle.

Help move NADH into the mitochondria. Where it is made into ATP during electron transport chain.

57
Q

How is b12 connected to citric acid cycle?

A

Co-factor in conversion of propionyl CoA to Succinyl-CoA

Human nutrition and physiology (17 decks)

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