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Nutrition Ceci > 7. the vitamins > Flashcards

7. the vitamins Flashcards

1
Q

What is a vitamin?

A

They are organic compounds that are required for:

  • growth
  • maintenance of normal health and metabolism
  • reproduction

They cannot be synthesized in the body with some exeption

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2
Q

Which vitamins can be synthesized in the body?

A
  • vitamin D: individuals with no sufficient UV light exposure have to take vitamin D from diet
  • Niacin: can be syntheszed from tryptophan
  • vitamin K: new born infants have low stores (produced by the microbiota)
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3
Q

Tell the common reasons for vitamin deficiency:

A
  1. Inadequate intake/absorption:
    (poor diet, losses during food preparation, low bioavailability, drugs, alcohol, diseases)
  2. Increased requirements:
    growth, ageing, pregnancy
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4
Q

Categorised vitamins:

A

fat soluble: A,D,E,K
water soluble:
B8 8 vitamins) and C

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5
Q

What vitamers are?

A

members of the same family of vitamins (ex. tocopherol belong to vitamin E)

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6
Q

What Provitamins are?

A

They are precursors that can be converted to yield a metabolic activelly form of vitamin

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7
Q

What is vit A ? Where you can find that in food?

A
  1. retinol (liver, fish oils, milk, eggs…)

2. carotenoids (beta, alpha carotene) have yellow green orange pigments can be found in plants fruits

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8
Q

What are the caroteinoids?

A

Around 60 in human diet but few in the human plasma
Carotenoids: carotens/zantophylls

Some of them can be converted and have provitamin A activity

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9
Q

Conversion factor for vitamin A?

A

estimation of vitamin A activity:

1 micro gram of retinol activity equivalents=12 micro grams of beta carotene and 1 micro gram of retinol

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10
Q

Describe absorption of vitamin A and carotenoids

A

70-90% of dietary retinol absorbed in the small intestine, it is transported together with fatty acids
The metabolism is quite similar to fat absorption:
food –> relase of retinol and betacarotene from matrix –> micells (they are fat soluble in fat, bile…) –> chylomicron that enter in the mucosa and then blood stream and in the liver then it can go into tissues

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11
Q

Source of carotenoids that have high bioavailability:

A

fruits, tuber, papaya, peach, melon, tomato juice

low bioavailability: tomato, carrots, peppers spinach,

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12
Q

What effect the bio availability of carotenoids?

A
  • physiocochemical properties: lutein, trans are the more available
  • food matrix and processing: pureè and processed food have highes bio availability

Heat treatmnet
homogenization
addition of fat
can improve the uptake of carotenoids (more soluble and easily accessible by enzyme)

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13
Q

Vitamin A functions and deficiency?

A

It plays a role in:
vision, growth, cell differentiation, immune functions, reproduction, healty skin, hair, membranes

deficiency symptoms ( Zinc deficiency cause it is required to make retinol binding proteins):
night blindness, damage at retina and cornea
XEROPHTALMIA( dry eye syndrome):
night blindness, bitots spots, dryness of corena, cause blindness)

RICORDATI DI DISEGNARE LA CURVA DELLA DOSE DI VITAMINE CHE LE PIACE TANTO

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14
Q

Who’s at risk of vit A deficiency?

A

premature infants, young children in developing countries, pregnant and lactating women in developing countries

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15
Q

What happens if you have too high vit. A?

A
  1. teratogenicity (increase risk of birth defect) max 3 mg day
  2. Accumulation in liver and other tissues
  3. Reduce bone mineral density lead to osteoporosis
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16
Q

Give examples about controversies about vit.A?

A
  • lycopene: prevent carcinogenesis and atherogenesis ( but studies shown negative effect of vitamin intake)
  • beta carotene and vit.E supplements increase mortality rate
  • supplements with vit.C, vitamin E or betacarotene fail in reduce cancer risks
  • betacarotene associated with excess of lung cancer
  • high beta carotens is also associated with low incidence of CVD and some other forms of cancer
17
Q

Vitamin D:

A

ergosterol –> vitamin D2
7-dehydrocholesterol –> vitamin D3
this conversion can happen vith irradiation and UV light and take place starting from the skin

souces: fish, eggs, mushrooms, milk

18
Q

Explain metabolism of vitamin D:

A

Both from skin and food: it pass through blood thaen liver then kidneys where it reach the active form: calcitriol

19
Q

Main functions in huamn metabolic processes:

A

Increase active calcium absorption ( maintain normal blood levels of calcium and phosphate, mineralization of bone, muscle contraction, cellular functions, gene transcription)

20
Q

What is the action of calcitriol?

A

increase absorption of Ca and P
maintain Ca-homeostasis in interaction with paratyroid hormone
regulate renal production/degradation
facilitate skeletal mineralisation

when there is too less calcium in blood we activate PTH (paratyroid hormone) to produce more cacitriol

21
Q

Vitamin D deficiency

A

Rickets ( low Ca)
Osteomalacia (weak soft bones)
Osteoporosis (low dense bones)

Causes are: reduce intake and uptake of cholecalciferol (vit.D)
disorder with abnormal gut function
reduced synthesis in skin

22
Q

what influence the reduce skin synthesis of vitamin D?

A

latitude and season
aging process
pigmentation
clothes

23
Q

Toxicity:

A

cannot be caused by prolonged exposure to sun

over supplementation can cause high blood pressure and calcinosis

24
Q

What’s vit.E?

A

Tocopherols

Tocotrienols

25
Q

Water soluble vitamins:

A

C and B
stored in the body for short times, sensitive to heat treatments and low pH
risk of deciency in individuals with: drugs, alchool, bowel diseases

26
Q

Examples of diseases caused by water soluble vitamins:

A

Beriberi (where polished rice is the main food) caused by THIAMINE deficiency, pellagra (tissues demage, dermatitis, depression, dementia) caused by NIACIN deficiency, rickets, Scurvy

27
Q

Vitamin B

A

it plays a role in all the cell cycle: glycolysis tcs cycle…

28
Q

VItamin B12:

A

eggs, meat, milk
It is hydrolyzed by protein in the stomach, bind to R proteins, bind to intrinsic factor, absorbed in the ileum and transported in the liver

29
Q

Function of B12:

A

help to maintain health nerve cells, and red blood cells

deficency can cause pernicious anemia

30
Q

What’s pernicious anemia?

A

It’s a form of megaloblastic anemia: large immature an dysfuncional red blood cells

31
Q

What are folate and folic acid?

A

Group of water soluble B vitamins
folic acid is the synthetic form of folate (broccoli, oranges…) have a bioavailability of 100%
the natural sources of folate are unstable during processing

32
Q

Funcion of folate in the body?

A

production of red and white cells
rna and dna
normal development of faetus in pregnant women

33
Q

Deficiency associated with folate?

A

Spina bifida (the neural tube doen not close all the way and results in demage to spinal cord and nerves, CVD, alzahimer, Megaloblastic anemia, dementia

Nutrition Ceci (12 decks)

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