Foods and Nutrition 1021 Study Guide - Midterm Guide: Vitamin B12 Deficiency, Pantothenic Acid, Gene Expression

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Definition and Classification of Vitamins:
Vitamins
Organic compounds vital to life
Indispensable to body functions
Needed in minute amounts
Non-caloric essential nutrients
Precursors/Provitamins
Compounds in foods converted to active vitamins
The only disease a vitamin can cure is the one caused by a
deficiency of that vitamin!
Summary of information for each vitamin: Table 7.3 pp 251-252 (fat-
soluble vit), Table 7.4 pp 253-255 (water soluble vit), including other
names, deficiency & toxicity symptoms
Vitamins fall into two classes:
Fat soluble
Water soluble
Vitamin Names:
Fat-soluble vitamins
Vitamins A, D, E, K
Water-soluble vitamins
B vitamins (thiamin [B1], riboflavin [B2], niacin [B3], folate, B12,
B6, biotin, pantothenic acid
Vitamin C
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Factors that destroy vitamins
Acids, bases, oxygen, UV light, heat
Fat Soluble Vitamins
Characteristics:
Vitamins A, D, E, K
Absorbed into the lymph, travel in the blood in association with
protein carriers
Dissolve in lipid
Require bile for absorption
Stored in the liver & body tissues
May be toxic in excess from supplements (A,D, K)
Deficiencies occur with low intake or fat malabsorption
Vitamin D is the most toxic
Vitamin A
Three active forms in the body:
retinol (stored in the liver),
retinal & retinoic (converted by cells from retinol)
Plant -derived precursor – Beta-carotene
Good food sources
Liver, fortified milk (active form of Vitamin A)
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Deep orange fruits & dark green leafy vegetables [sweet potatoes,
carrots, spinach, ‘bok choy’, broccoli, apricots, mango, cantaloupe]
(source of beta-carotene)
Beta-Carotene:
Most abundant carotenoid precursor for vitamin A
Dietary anti-oxidant
Measured in retinol activity equivilents (RAE)
Convert B-carotene [& other carotenoids] to retinol
Takes 12 ug B-carotene to equal 1 ug retinol for the body
B-carotene in excess – not toxic compared to retinol; turns people bright
yellow/orange if eaten in excess [due to build up in fat tissues beneath
the skin]
Rich source of B-carotene: carrots, sweet potatoes/yams, pumpkins,
mango, cantaloupe, spinach, broccoli
Other colorful veggies: red cabbage, beets, yellow corn, white yam – poor
sources of B-carotene
Functions of Vitamin A:
Eyesight:
1. Light perception at the retina
a. Pigment rhodopsin contains vitamin A
2. Maintains healthy crystal-clear cornea
a. Covering the outside of the eye
Process:
when light hits the eye, it bleaches the rhodopsin,
a piece of vitamin A breaks off, which conveys the sensation of sight to
the optic center of the brain.
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