vitamins-fat soluble

Question 1

what are vitamins and what is the function of them?

Answer 1

-Vitamins are all organic compounds- all contain carbon
Functions:
-essential for many body processes
-play role in digestion, utilisation of CHO, proteins and fats
-Do not produce energy when broken down
-are co-enzymes -they assist enzymes and other biological factors that release energy from CHO, protein and fats

Question 2

how are vitamins classified?

Answer 2

-classified according to solubility
Fat soluble vitamins-function in fatty tissues (cell membranes/ nerve tissues)
Water sol vitamins- function in watery areas (fluids outside/ inside body cells)

Question 3

what are the water soluble vitamins?

Answer 3

-Vit C
-B vitamins:
Niacin B3
Pantothenic Acid
Riboflavin B2
Folic Acid Thiamin B1
Biotin
Vit B6
VIT B12

Question 4

what are the differences between fat soluble and water soluble vitamins?

Answer 4

-Absorption- fat sol vit absorbed into lymph then blood/ protein carrier
-water sol absorbed directly into the blood
-Storage- fat sol are stored long term in liver and adipose tissue
-water sol are stored short term- not easily stored
-excretion -fat sol are less readily excreted and remain in fat storage sites
-water sol vitamins are detected by kidney and removed in urine

Question 5

what is vitamin A and how is it absorbed?

Answer 5

-retinol
-carotenes are also source of vitamin A as they can be converted into retinol
-Retinol needs bile salts, vitamin E and adequate protein to be absorbed
-Carotene not absorbed as efficiently (only 9-17%)

Question 6

where is vitamin A stored and how is it transported?

Answer 6

-Stored in liver, kidney and pigment layer of eye
-Transported by being bound to retinol binding protein and pre-albumin

Question 7

functions of vitamin A?

Answer 7

-vision
-bone growth
-reproduction
-epithelial growth and differentiation
-overall growth
-anti infection

Question 8

How does vitamin A contribute to vision?

Answer 8

-Controls the speed at which eye adjusts from bright to dim light
-causes rhodopsin to be resynthesised in the dark and broken down when exposed to light

Question 9

Effect of vitamin A deficiency?

Answer 9

-night blindness- people take a long time to recover enough rhodopsin to be able to see in dim light
-May also cause collapse of eye ball
-causes epithelium cells to beecome dryer and harder as more vitamin A that senters cell the greater the mucus secretions
-increased possibility of infection

Question 10

What are the signs of vitamin A deficiency?

Answer 10

-follicular hyperkeratosis
-rough skin
-changes in taste and smell

Question 11

what factors affect vitamin A deficiency in low income countries?

Answer 11

-dietary inadequacy (low fat, low protein)
-low liver reserves at birth
-low levels in breast milk
-frequent infections

Question 12

name the Dietary sources of vitamin A

Answer 12

Retinol(found only in animal sources):
-meat (49%)
-liver (44.5%)
-fats (23%)
-milk/dairy (22%)

Carotene
-vegatables (83%)
-carrots (55%)
-milk/ dairy (5%)

Question 13

Effect of vitamin A excess/ whats it caused by?

Answer 13

-caused from taking supplements
-can accumulate in liver and result in birth defects, permanent damage to liver/eyes
-reduced bone density

Question 14

recommneded intake of vitamin A

Answer 14

500ug-men, 400ug- women, 250ug- children

Question 15

what is vitamin D also known as and why is it different from other vitamins?

Answer 15

-differs from other vitamins as body can synthesise it with help of sunlight so is non essential
-aka calciferol

Question 16

vitamin D functions?

Answer 16

-bone making and maintenance
-assists in absorption of dietary calcium
-helps make calcium and phosphorus available in blood

Question 17

vitamin D sources?

Answer 17

-produced in skin by U.V radiatio of 7-dehydrocholesterol
-dieatary-firsh-liver oil, flesh of oily fish, egg yolk, liver

Question 18

where is vitamin D absorbed?

Answer 18

-in intestine

Question 19

Describe how vitamin D is activated in the body?

Answer 19

-starts in liver cells where it is hydroxylated
-then in kidney its further hydroxylated to metabolically active form of the vitamin. Parathyroid hormone is essential for this to happen

Question 20

Where does vitamin D act within body?

Answer 20

-gut (calcium absorption)
-kidney (calcium excretion)
-bone (calcium storage/ bone formation)
-parathyroid gland (inhibits parathyroid hormone release)

Question 21

what is the result of a vitamin D deficiency?

Answer 21

-rickets (symptoms- skeletal deformity, bow legs, poor growth, delayed dental eruption, fractures)
-osteomalacia (muscle weakness & skeletal pain, x rays showing loss of bone density

Question 22

which groups are most at risk of vitamin D deficiency and what are the risk factors?

Answer 22

-Uk asians
-inc uv light deprivation, exposure to sunlight, fibre, less calcium in diet, less animal foods in diet
-Housebound/institutionalised- (lack of exposure to sunlight)

Question 23

what can an excess of vitamin D cause?

Answer 23

-leads to increase calcium absorption- leads to calcium depositis in soft tissue
-from sunlight- can cause skin cancer

Question 24

what is vitamin E and what is its functions?

Answer 24

-is an antioxidant
Functions:
-effective in preventing oxidation of polyunsaturated fats
-important antioxidant effect in lungs where cells are exposed to high conc of oxygen
-helps prevent heart disease by protecting LDL from oxidation

Question 25

who can have a vitamin D deficiency?

Answer 25

-Deficiency is rare but can happen in those who cant absorb fats (liver, gallbladder and pancreas disease)

Question 26

Sources of vitamin E?

Answer 26

-veg oils
-fatty parts of animal foods

Question 27

Vitamin K function?

Answer 27

-blood clotting (caused by synthesis of proteins)
-bone health (works with vit D to regulate calcium)

Question 28

why is vitamin K deficiency rare?

Answer 28

as it is widely present in foods and vit K can also be synthesized by gut bacteria

Question 29

which groups are at risk of vitamin K deficiency?

Answer 29

-newborn infants (placenta has difficulty delivering fat sol substances, milk fed to babies is sterile so no bacteria in gut to synthesize the vitamin)
-Patients with defective absorption (eg.with gall stones, colitis or pancreatitis)
-Using antibiotics frequency (destroys gut flora which destroys production of vitamin

Question 30

what can happen if there’s a vitamin K deficiency in newborns and how is this prevented?

Answer 30

If there is deficiency can cause spontaneous bleeding- haemorrhagic disease of the new born
-to prevent this babies are given a vitamin K injection after birth

Question 31

how is vitamin K deficiency identified?

Answer 31

by measuring prothrombin time-time taken fir blood to clot (vit K status is inversely related to clotting time)

Question 32

sources of vitamin K?

Answer 32

-green beans
-cauliflower
-spinach
-brocolli
-liver
-cheese