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Yr 1 Nutrition Vits and Mins Lecture > Vits and Mins Lecture Dec 2017 > Flashcards

Vits and Mins Lecture Dec 2017 Flashcards

1
Q

What is the definition of a mineral?

Can the body synthesis minerals?

A

A naturally occurring INORGANIC substance with its own crystalline structure.
It is solid and in different colors
No - have to be eaten daily

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2
Q

What Vitamins and minerals do humans need and what are they used for in the body?

A

B1, 2, 3, 5, 6, 7, 9 and 12
Ca, Mg, Zn, P, K Na and Cl
Used for energy production and other metabolic actions

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3
Q

What is bio availability?

A

Absorption of a mineral AFTER digestion from food and BEFORE its use in tissues and cells

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4
Q

What can affect bio availability?

A

Body mineral status (eg, deficiency increases abs)
Substances present in foods (phytates, Vit C etc)
Other minerals present in food (eg Zn abs reduced by Fe supps)
Disease states
High concentration of one mineral in the intestine (eg, excess Ca binds to P)

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5
Q

Define ‘sub clinical insufficiency’

A

Reduction in nutrient stores with no symptoms. Reduction of enzyme activity (lack of coenzymes) Adverse behavioural effects

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6
Q

Define end-stage nutrient inadequacy

A

Classical deficiency syndromes

Terminal tissue pathology

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7
Q

Name 5 other metabolic reactions that involve minerals

A 
Bone mineral density 
Muscle contractions
Bone health and osteoporosis
High BP
T2DM
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8
Q

B7 - Biotin - where is B7 aborbed and stored

A

Absorbed in small intestine and uses a sodium dependent transporter.
It is stored in the mitochondria

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9
Q

What is B7 involved in within the body

A

B7 is a coenzyme. Enzymes containing B7 are involed in gluconeogenisis, propionate metabolism & fatty acid synthesis
Also growth, development and energy production
***B7 main role - synergy with other Vits and Mins and support of Kreb cycle activity

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10
Q

What organ has the highest concentration of B7

A

The brain (50 x higher than plasma)

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11
Q

Name some food sources for B7

A 
Bean Sprouts
Bulgar Wheat
Egg Yolk
Kidney (high)
Liver (high)
Oats
Wholegrain cereals
Leafy greens
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12
Q

Is there a recognised RDA for B7

A

Currently no. AI for an adult is 35-40ug/day

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13
Q

What is B7 bound to, where is it absorbed and where is it stored

A

It is bound to protein, which is metabolised in the intestines to yield FREE BIOTIN - absorbed then in SI
and stored in the mitochondria

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14
Q

What can impair absorption of B7

What can enhance absorption of B7

A

Chronic alcohol intake
Raw egg whites (avidin can bind biotin)
Cooked eggs are fine though

Colon absorption may be enhanced by the effects of a vegetarian diet on gut flora

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15
Q

What skin conditions has B7 been shown to help in

A

Cradle cap
Seborrheic dermatitis
no evidence that supplementation will help
Brittle nails
Diabetes(may lower Haemoglobin A1c - marker of long term blood sugar levels)

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16
Q

Who are are risk of B7 deficiency

A

Deficiency is unknown except in parenteral nutrition and the consumption of LARGE amounts of egg whites uncooked.

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17
Q

Name 6 deficiency symptoms of B7

A 
Scaly and seborrheic dermatitis
Hair loss
Nausea
Depression 
Burning/itching sensations
Glossitis (red tongue)
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18
Q

What can affect a persons individual requirement of B7

A 
B7 is B5 and Na+ dependent
B7 - shown to be an intestinal bacterial source
Long term AB use could decrease B7 available from gut bacteria
Elderly (poor gut function)
Pregnancy (need for more - rapid growth)
Smoking - increases catabolism
GIT diseases ie Crohn's, colitis, IBD
T2DM
Heavy alcohol intake
Raw egg whites (avidin)
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19
Q

Name 3 meds that B7 can interact with

Are there any cases of toxicity

A

Antibiotics
Carbamazepine
Isotretinoin
There are no known cases of B7 excess leading to toxicity

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20
Q

How many types of folate are there

A

There are 2 types:
Folate from food
Oxidised monoglutamate form used in supps
folate is the generic term describing both

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21
Q

What are B9’s main functions

A

Coenzyme for single carbon transfers in synthesis of nucleic acid and metabolism of AA’s
The conversion of homocysteine to methionine
Cell division

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22
Q

Where is B9 absorbed and stored

A

Food sources are hydrolised to monoglutamate form in gut then absorbed by active trans across intestinal mucosa
Stored in the liver (metabolised) with unmetabolised amounts in blood and tissues
THF - tetrahydrofolate) active in metabolic reactions

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23
Q

Does folic acid occur naturally

A

No. Folic acid is the synthetic form found in supps
Synthetic folate is more bioavailable than food folate
Folate unstable after heating 60 degress

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24
Q

Briefly explain what is meant by ‘the folate trap’

A

After absorption a methyl group is added to folate and then delivered into the cells
In order for folate to function the methly group must then be removed by an enzyme that requires B12
WITHOUT THAT HELP FOLATE iGETS TRAPPED inside the cell in it’s methyl form unable to do its job - DNA synthesis and cell growth impaired (metabolic situation)

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25
Q

Name some sources of B9

A 
Abundant in foods of plant origin (foliage)
Green leafy veg richest source
Legumes
Citrus fruit
Live 
Spinach
Red Kidney beans
Broccoli
Asparagus
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26
Q

What is the adult RDA and what are the supplement ranges for B9

A

RDA 330ugDFE/day
Supp range - 1000-5000mcg (as folic acid)
TUI for adults is 1000ug/day

400mcg recommended during preconception and first trimester

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27
Q

Why is folate supplementation recommended pre-conception and during 1st trimester

A

Taken preconceptionally folic acid has been shown to prevent neural tube defect such as spina bifida
400ug BEFORE CONCEPTION as closure of neural tube takes place on day 28 of pregnancy before woman knows she is pregnant

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28
Q

What can destroy folate in foods and where is it absorbed

A

Heat and oxidation in cooking and storage can destroy up to 50%.
Absorbed in SI

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29
Q

Is the bio availability from food as good as that from supplements for B9

A

No. It is approx 80% of that from supps (higher than previously thought)

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30
Q

What can B9 be used for therapeutically

A

Lowering homocyteine - this also reduces progression of atherosclerosis and improves arterial blood flow
300mcg dietary folate associated with lower risk of stroke and CV disease
Dietary folate seems to reduce risk of breast cancer
Supplementing alongside antidepressants may improve treatment response
Vitiligo - needs medical supervision

31
Q

Name two functions that are impaired by B9 deficiency

A

Cell division

Protein sythesis

32
Q

In B9 deficiency what type of cells are affected first and what does this mean for the body

A

Fast dividing cells affected first - RBC’s and GIT cells
This results in Megaloblastic anaemia and
GIT deterioration - GIT deterioration can be triggered by alcohol abuse= increased folate loss from the body = further GIT weakening and folate loss (viscous cycle)

33
Q

What can high levels of homocysteine indicate in the body

A

Could indicate B9 insufficiency (because body unable to convert homo to methionine) BUT this is not always the case - B12 could also mask this situation

34
Q

What are insufficient levels of folate in pregnancy a risk of

A

Neural tube defects and foetal growth retardation

35
Q

Name 5 things other than pregnancy and high alcohol intake that can affect individual requirements of B9

A

Cancer
Chickenpox/measles
Burns
Blood loss

36
Q

Name 3 medications that may interact with B9

Is B9 toxic?

A

Antacids
Aspirin
Diuretics

Folate in foods shows no sign of toxicity
Excess folic acid has been linked to Zn impairement in the past. No recent studies available

37
Q

Name the 5 different types of Vit B12

A

Methylcobalamin - most active
Hydroxycobalamin - created by bacteria in gut naturally and easily converted
Cyanocobalamin - synthetic version
Adenosylocobalamin - occurs during Krebs Cycle
Aquacobalamin - precursor of adeno and methyl

38
Q

What is B12’s primary role

A

It is a one carbon (methyl) donor which facilitates metabolism of folic acid and synthesis of DNA

39
Q

How is B12 released in the stomach, what is it combined with and where is it absorbed

A

B12 is protein bound and released by HCI and gastric protease.
It is combined with IF (glycoprotein) found in parietal cells
Absorbed in the terminal ileum

40
Q

Do high levels of IF increase or decrease Vit B12 absorption

A

Decrease it

41
Q

What role does B12 play in the nervous system

A

B12 plays a role in the sythesis of myelin. If levels of B12 decrease this results in abnormal levels of MMA that can lead to defective nerve transmission

42
Q

Can humans synthesis their own B12

A

Yes from bacteria but it is not absorbed

43
Q

B12 on foods are through……

A

Bacterial synthesis or contamination

44
Q

What animal sources provide B12

A

Only found in foods of animal sources (where it originates from the ingestion of bacterial-contaminated food)
Sources include - Meat (liver good) Fish, Eggs, Milk and Cheese

45
Q

What is the EU AI set at for adults for B12

A

19-50 yoa 4ug/day

Supplement range is 300-8000ug/day

46
Q

How does cooking affect B12

A

As B12 is found in food bound to protein so 70% of its activity is retained during cooking
However, large amounts lost in pasteurised or evaporated milk

47
Q

Explain the steps of absorption of B12

A

1 Must be released from protein in stomach by pepsin digestion
2 Combines with R-protein moving into duodenum
3 Released from R-protein there and binds to IF (IF can only bind cobalamins mentioned earlier)
4 The IF-Vit B12 complex then absorbed in distal ileum

48
Q

Where is most Vit B12 stored and approx how much is there in mcg’s in an adequately nourished person

A

In the liver - about 2000mcg (a store of 5-7 years!)

49
Q

Who may need extra B12 for specific therapeutics

A

Elderly - those who take B12 orally are more likely to have NORMAL B12 levels than those who do not
B12 + B9 and B6 = can reduce serum homocysteine

50
Q

Does supplementing with B12 B6 and B9 therefore prevent death or CV events such as stroke?

A

Whilst this complex can reduce total homocysteine it does NOT help prevention of death or CV events such as stoke

51
Q

What other group of people may need B12 supplementation

A 
Vegans
In pregnancy
Thyrotoxosis
Malignancy
Liver/Kidney disease
52
Q

Name 5 signs of insufficiency and 5 signs of deficiency for B12

A

Insuff - Fatigue, weakness, No appetite, Mego anaemia, tingling in hand and/or feet
Def - Difficulty maintaining balance, confusion, dementia, poor memory, nerve damage

53
Q

What factors may effect individual requirements and what is the toxicity level associated with B12

A

Malabsorption of B12 due to low IF levels could lead to pernicious anaemia (presenting like megalo anaemia)
Age related degen of gastric cells = less IF
Hereditary deficiency of IF
Autoimmune destruction of IF
Crohns, IBD
Unhealthy vegans/veggies
B12 is NON TOXIC from foods and as is water soluble neither is supplementing (no upper limit has been defined due to its safety)

54
Q

Name 2 meds that can inhibit B12 absorption

A

Metformin and PPI’s

55
Q

What are the 2 forms of Vit C called

A

L-Ascorbic acid

Dehydroascorbic acid - an oxidised form of ascorbic acid

56
Q

Is Vit C fat or water soluble and where can it be found in the body

A

Water soluble found in most tissues in the body

57
Q

Can humans synthesis C

A

No, we have lost the ability to do so

58
Q

What are the names of the transporters that import ascorbate over and into the plasma membrane and absorb it in the distal ileum

A

SVCT - sodium ascorbate C-transporters and GLUT - hexose transporters

NOTE - SVCT2 is the only one that facilitates ascorbic acid into almost every tissue except RBC’s

59
Q

What are the functions of C

A

Ascorbate presents electrons for essential enzyme reactions which are primary antioxidant scavenging radicals found in plasma or cells

Vit C is also used for biosynthesis of:
Collagen, Protein metabolism, Neurotransmitters (conversion of tryptophan to tyrosine)
Thyroxine synthesis
Adrenal steroid hormone synthesis

60
Q

How does Vit C increase Fe absorption thus keeping Fe bioavailable

A

C increases iron absorption (non-heme) by protecting it from oxidation and enhancing intestinal absorption by keeping it in its Fe2+ form (Fe3+ form is not bioavailable)

61
Q

What is the term used for the oxidation of organic substrate by Fe and why is C involved in this process

A

The term used for oxidation of inorganic substrates by Fe is the Fenton Reaction.
C is involved because ascorbic acid can recyle Fe3+ and Fe2+

62
Q

Where is C stored in the body

A

There are no specific storage sites for C but adrenals, pituitary gland and WBC’s appear to have highest concentrations

63
Q

What are the best sources of C from food

A 
Blackcurrants, Redcurrants
Citrus fruits
Strawbs, Blacks, Blues
Kale, Rocket Watercress
Peppers
64
Q

What can cause significant losses to C in food

A

When the veg wilts or when it is cut (releasing ascorbate oxidase from plant tissue)
Leaching into water
Atmospheric oxidation when foods are left to stand before serving

65
Q

What is the RDA for male and female adult

What is the supplement range

A

PRI’s - F 80mg pe day, male 110mg/day

250-10,000mg

British recommendation for RNI is currently 40mg

66
Q

What can be done to foods containing C to help retain the vitamin

A

Refrigeration and quick freezing

Most frozen foods have higher levels of C than fresh

67
Q

Where is C absorbed

A

Both ascorbic acid and dehydroascorbic acid are absorbed in the mouth and SI

68
Q

What happens to unabsorbed ascorbate

A

Unabsorbed ascorbate from high doses is a substrate for intestinal bacteria metabolism causing GIT discomfort and diarrhoea

69
Q

What transports C into the cells

A

Glucose transporters

70
Q

What happens to the process of C by glucose transporter in a person with high blood glucose (diabetic)

A

Vit C uptake is significantly inhibited

71
Q

What can C be used for in specific therapeutics

A 
AMD (age related macular degeneration)
Albuminuria 
Atherosclerosis 
Cancer - dietary Vit C might decrease mouth and some other cancers
Gallbladder disease
H Pylori 
Osteoarthritis
Sunburn
72
Q

Insufficiency - What could increase a persons need for C

A

Burns
Infections
Certain meds (Aspirin, oral contraceptives)
Smokers (inc passive) - increased oxidative stress
Anyone on limited eating regime
Malabsorption and GIT disease
Immune issues (recurring infections and colds)

73
Q

Deficiency - What are the symptoms of C

A 
Scurvy
Muscle loss
Rough dark brown scaly skin
wounds that do not heal
bone fractures due to not healing
74
Q

What factors can affect individual requirements

Is Vit C toxic

A

Excess blood glucose can inhibit C uptake = oxidative stress
Cancer treatment CV disease
At high levels (3000mg/day) can result in diarrhoea, ab cramps and nausea
Long term high dosage C supplementation can adversely affect people with Fe overload (Fe induced free radicals) C would therefore be a pro-oxidant

Yr 1 Nutrition Vits and Mins Lecture (2 decks)

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