Vitamins Flashcards
fat soluble
A (retinol, beta carotene)
D (cholecalciferol, ergocalciferol)
E (tocopherol)
K (naphthoquinone)
water soluble
C (ascorbic acid) B Group: B1 (thiamine) B2 (riboflavin) B6 (pyrodoxine) B12 (cobalamin) folic acid niacin
forms of vitamin A
retinol (pure vit A)
-animal sources
eg fish, fish oils, butter
beta carotene
-brightly coloured fruit and veg
eg carrots, apricots, tomatoes
functions of vit A
- produces rhodopsin to aid night vision
- essential for lining membranes
- aids growth and repair of cells
- healthy hair and skin (antioxidant)
effects of vit A deficiency
- night blindness
- xerophthalmia (dry eyes)
- stunted growth in children
- dry mucous membranes - rough and dry skin
vit A RDA
children - 400-500mcg
adolescents - 600-700mcg
adults - 600-700mcg
pregnancy/lactation - 950mcg
properties of vitamin A
retinol
- yellow fat soluble alcohol
- insoluble in water
- heat stable
- reduced by dehydration
beta carotene
- bright orange or yellow oil
- insoluble in water
- heat stable
- sensitive to dehyration
hypervitaminosis - excess vit A
causes- dry skin enlarged liver fatigue hair loss risk of birth defects and miscarriage death
types of vitamin D
cholecalciferol
from sunlight or food eg oily fish
-sunlight converts 7 dehydrocholesterol in the skin to cholecalciferol
ergocalciferol
from fungi or yeast
-action of the sun converts ergosterol to ergocalciferol
functions of vitamin D
strong bones and teeth
aids absorption of calcium and phosphorous
prevents rickets and osteoporosis
regulates blood calcium levels
effects of vit D deficiency
rickets in children
osteomalacia
osteoporosis
dental decay
vit D RDA
children - 10mcg
adolescents - 15 mcg
adults - 10 mcg
pregnancy/lactation - 10 mcg
properties of vit D
white crystalline solid fat soluble insoluble in water stable to heat stable to acids, alkalis and oxygen
hypervitaminosis - excess vit D
more common among young children than adults due to high concentration of calcium in the blood
symptoms- nausea mental confusion vomiting and thirst loss of bone mass
vit E sources and deficiency
margarine, egg yolk, spinach, pulses
rare for the majority of the population
functions of vit E
- acts as an antioxidant
- destroys free radicals -reduces effects of aging
- protects healthy blood cells from damage
- strengthens immune system
- helps ease pre-menstrual tension
properties of vit E
fat soluble antioxidant insoluble in water delays rancidity and oxidation damaged by alkalis, oxygen and light heat stable, stable in acids
vit K sources
plant: green veg, cereals
animal: meat, liver, eggs
body: made by bacteria in the gut
functions of vit K
- for synthesis of prothrombin, essential for clotting blood
- regulates calcium balance in bones
effects of deficiency in vit K
delayed clotting of blood
vit C functions
antioxidant, prevents CHD and some cancer
helps white cells fight infections - strong immune system
essential for collagen formation
strong bones and teeth
essential for absorption of non haem iron
effects of a deficiency in vit C
scurvy in severe cases
anemia
slower healing of cuts and wounds
bruising and bleeding due to weaker blood vessels and tissues
RDA of vit C
children: 45mg
adolescents:60mg
adults:60mg
pregnancy/lactation:80mg
properties of vit C
white crystalline acid with sharp flavour
destroyed by alkalis, dry/moist heat and enzymes
acts as an antioxidant
affected by metals eg copper, iron
folic acid sources
fortified foods
wholegrain cereals
leafy green veg
offal
functions of folic acid
essential for manufacture of DNA & RNA
protects against neural tube defects eg spina bifida
assists B12 in the formation of red blood cells
assists protein metabolism
effects of a deficiency in folic acid
tiredness and fatigue
anaemia in young children/pregnant women
risk of neural tube defects in foetus
