Vitamins Flashcards
fat soluble vitamins
A, D, E and K
Clinical significant relevance of distinguishing fat soluble vitamins and water soluble vitamins
conditions which impair absorption of fat such as digestion problems : cystic fibrosis, gull stone and intestinal disease: celiac disease, Crohn’s disease causes vitamin difficiencies
water soluble vitamins
C &B complex vitamins
what is vitamin
an essential nutrient not used for energy production
what is difference between vitamins and Minerals
Vitamins are organic molecules, complex molecules containing carbon
Minerals, are non organic
Cornea
clear membrane on the anterior aspect of the eye, transmits light to the retina
Retina
layer of nerve cells and receptors on the posterior part of the eye - detects light and turns ti into electrical signals
Cellular differentiation
process by which cells mature and become specialized for their particular function
Dietary role Vitamin A
Vision: important for function of the retina and the cornea
Epithelium: important for cellular differentiation
Bone: regulates functions of osteoclasts, which remodel bone structure
General signalling an active form of vitamin A (retinoic acid) serves as a signal that regulates the functions of a wide variety of cells (immune, skin, bone)
Forms of vitamin A
Active forms: retinol, retinal - found in animal products
Precursor forms: beta-carotene-orange pigment found in animal sources of vitamin A
Dietary source of Vitamin A
Bright orange and darck green: Carrots, pumpkin, sweet potatoes, mangoes, apricots, spinach, broccoli, bok choy
Animals: liver, daily products, fish oil, eggs
Vitamin A dificiency
Visual: retina - night blindness,
cornea- progressive drying and opacification (clouding) that can result in permanent blindness -xeropthalmia
Epithelial cracking and hardening of skin, poor development of epithelial membranes
Immune: impaired immunity, infections
Bone and growth: failure to grow, reduction of enamel, Xerophalmia
mostly aected in 3rd world in energy deficient malnutrition. Severe vitamin A dificiency - visual symptoms and diarrhea milder vitamin A dificiency - poor function of the immune system
Vitamin A toxicity
Most toxic vitamins
Acute: from ingestion of foods very high in vitamin A such as polar bear liver, nausia, vomiting, diarrhea joint pain, headache, blurry vision, muscle and abdominal pain
Chronic: from elevated supplement intake, bone loss, liver damage, hair loss, dry skin, weight loss, anemia
neurological sypoms
Excess vitamin a during pregnancy is linked to serious birth defects
Vitamin D
Act as biochemical signal
Different forms: main ones vitamin D2 (only in plants) and D3
D3 converted to calcidiol in the liver, which is convereted to calcitrial (active) in kidneys
Skin can sythesize from a steroid precursor when exposed to UV light
Vitamin D dietary role
Bone: Stimulates intestinal uptake of calcium and phosphate
Works with PTH to reduce renal loss of calcium
Other stimulates the maturation of a range of cells, including those of the immune system
Evidence is building that it reduces the risk of cardiorespiratory and autoimmune disease as well as some cancers
Vitamin D sources
Sunlight The sun transforms 7 -dehydrocholesterol into cholecalciferol
The liver stores cholecalciferol and converts it into calcidiol
The kidneys convert calcidiol to calcitriol (active form of vitamin D)
Food: found almost exclusively in animal products
Fortified milk fish, other seafood liver
Vitamin D dificiency
Rickets: childhood disease, development of softened, malformed bone
Rickets: bowed legs, beaded ribs, protruding belly
Osteomalacia: resulting in spine abnormalities, fractures and sore bones and muscles
Vitamin D dificiency contributes to osteoporosis and many others heart disease, stroke, etc.
Vitamin D toxicity
High doses of vitamin D show significant toxicity
Acute: hypertension, kidney failure, muscle weakenss, elevated serum calcium
Chronic: calcification in soft tissues, kidney failure, plus siminar to acute.
Toxicity is not caused by excessive sunlight or food, but always over prescription of D supplements
vitamin D RDA
Children 10 ug/day
Adult 15ug/day
Oder than 70 20ug/day
Has been suggested by some that higher intakes may help combat chronic disease
Tolerable upper intake
Infants 25 ug/day All others 50 ug/day
2 cups of milk or 3 oz of salmon provide a RDA. Toxic dose is 1 kg of salmon each day