Week 9 Water soluble vitamins pt 1 Flashcards
(37 cards)
What are vitamins? how mant vits eessential?
- A group of chemically unrelated compounds - that is, carbon-containing compounds - occurring in living tissues - organic
- Required in the human body in minute quantities for normal cellular functio
- crucial for normal functioning, growth and maintenance of body tissues.
- 13 vitamins recognised as essential for humans
Where are fat soluble vitamins stored in body
mainly in the liver–until needed
Where are water soluble vitamins stored in body
in the tissues–briefly
Describe the movement of water soluble vits in the body and 2 exaples
- B group vitaminsa nd Vitamin C
- absorbed directly into the blood and travel freely.
- Freely circulate in the water-filled compartments of the body
– They are excreted in urine.
Describe the movement of fat soluble vits in the body and examples
- vitaminsA,D,K,E
- absorbed first into the lymph, then the blood
- Many require protein carriers.
- They are stored in cells associated with fat.
- They are less readily excreted, more likely to reach toxic levels when over consumed.
What is Bioavailability
the rate and extent that a nutrient is absorbed and used.
What 5 factors determine the bioavailability of a vitamin
- efficiency of digestion and time of transit through the GI tract
- previous nutrient intake and nutrition status
- other foods consumed at the same time
- method of food preparation (raw, cooked or processed)
- source of the nutrient (synthetic, fortified or naturally occurring).
What are precursors
- also known as provitamins
- converted to an active form of the vitamin when entered body
What are 5 ways to minimise vitamins losses in kitchen
-refrigerate (most) fruits and vegetables to slow the degradation of vitamins
- store fruits and vegetables that have been cut in airtight wrappers to minimise the oxidation of vitamins
- rinse fruits and vegetables before cutting to prevent losses during washing
- use a microwave oven or steam vegetables in a small amount of water, and add vegetables after water has come to a boil to minimise losses during cooking
- avoid high temperatures and long cooking times
What 8 b group vitamins are water soluble
- thiamin
- riboflavin
- niacin
- biotin
- pantothenic acid
- vitamin B6
- folate
- vitamin B12
- vitaminC.
Where are water soluble vits found in foods
watery compartments
How do vitamins work
- Involved in the catalytic action of the enzymes in the body’s cells
- Members of the B group are part of the enzyme system which controls the release of energy from food – cannot proceed without the specific vitamin in its coenzyme form
Describe the 4 steps to coenzyme action
- Without coenzymes, compounds A, B and CD don’t respond to their enzymes.
- With the coenzymes attached to enzymes compounds are attracted to enzyme sites
- reactions proceed instantaneously, coenzymes often donate or accept electrons, atoms or groups of atoms.
- The reactions are completed with either the formation of a new product, AB, or the breaking apart of a compound into two new products, C and D, and the release of energy
Describe thiamin (vit b1)
vitamin part of the coenzyme thiamin pyrophosphate (TPP), which assists in energy metabolism
- involved in conversion to pyruvate to acetly coA
- Absorbed in the duodenum and jejunum
- Active transport, inhibited by alcohol
- Tissues take up thiamin and phosphorylate for utilisation
- Excreted in the urine, may also be lost in sweat
- Little storage in the body and biochemical deficiency can occur within a few days
4 deficiency symptoms of thiamin
– Enlarged heart and possible cardiac failure.
– Muscular weakness.
– Apathy, poor short-term memory, confusion and irritability.
– Anorexia and weight loss.
What 2 diseases is caused my thiamin deficiency
- disease beriberi
- Wet beriberi presents
->with oedema (High CHO Intake) - Dry beriberi presents with
-> muscle wasting (Low E intake) - Wernicke-Korsakoff syndrome is a severe deficiency that develops in those who abuse alcohol
What are 3 good food sources of thiamin
Whole grains, breakfast cereals, meats provide a small amount. eg pork chop soy milk cornflakes
What is the RDI of thiamin for men and women
- MEN: 1.2 mg/day.
- RDI women: 1.1 mg/day.
What toxicites for thiamin
none
3 ways to minimise thiamin losses
- Steaming and microwaving are cooking methods that conserve thiamin.
- Thiamin leaches into water with boiling or blanching.
- easily destroyed by heat.
What is riboflavin (vit b2)
- Absorbed in the upper small intestine
- Milk and eggs contain relatively large amounts of free riboflavin
- Most of the B2 present in foods is present as Flavin coenzymes
- No significant storage, surplus intake is rapidly excreted in the urine
- is part of the FADH complex, and others
What is the rdi for riboflavin in men and women
- Men 1.3 mg/day.
- RDI women: 1.1 mg/day.
What 5 defiicney symptoms w riboflavin
- Deficiency related to role in metabolism, so tissues with rapid turnover are first affected.
- Inflamed eyelids, sensitivity to light, reddening of cornea.
- Sore throat, cracks and redness at corners of mouth.
- Painful, smooth and purplish red tongue.
- Skin lesions covered with greasy scales.
Is there any toxicities w riboflavin
none
