Vitamins
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what are vitamins?
organic nutrients that are required in small quantities for a variety of biochemical functions and which generally cannot be synthesized in the body and must be supplied by the diet. 13 are universally recognized.
vitamins function in vivo as… (3 answers)
coenzymes or their precursor - components of the antioxidative defense system - factors involved in genetic regulation
what are the 13 vitamins?
A, B1, B2, B3, B6, B7, B8, B9, B12, C, D, E, K
what does vitamin restoration mean?
addition to reach the “original” concentration of nutrients
what does vitamin fortification mean?
addition of nutrients to make the item a good or superior source of that nutrient
what does vitamin enrichment mean?
addition of specific amounts of selected nutrients according to the standards of FDA
what does vitamin nutrification mean?
generic term for any addition of nutrients to foods
what is a fat-soluble vitamin?
one that can dissolve in lipid solutions, these are absorbed in the intestinal tract with the help of lipids
what is a water-soluble vitamin?
can dissolve in water solutions. these are readily excreted from the body
what is hypervitaminosis?
a condition of abnormally high storage levels of vitamins, which can lead to toxic symptoms.
which vitamins are primarily at risk in hypervitaminosis?
fat-soluble since these are stored by the body for longer period than the water-soluble vitamins
which vitamins are the least stable?
folate and ascorbic acid may be lost 100% in cooking. B1(thiamin) 80%, K, B2(riboflavin) and B3(niacin) 75%
when to tomatoes contain the most vitamin C?
just before maturation, then it decreases again
why do we need vitamin A, retinol?
it is needed by the retina (näthinna) as retinal combines with the protein opsin to form rhodopsin, a light-absorbing molecule
what is another function of vitamin A in the body?
an important hormone-like growth factor for epithelial and other cells
what role do carotenes play in vitamin A metabolism?
it is cleaved by an enzyme and converted to retinol in herbivores and omnivores. pure carnivores cannot and carotenes do not act as vitamin A in these animals
deficiency of retinol may cause
night blindness, xerophthalmia (total blindness), abnormal bone development, disorders of reproductive system
what are some sources of retinol?
cod liver oil, liver, chili, sweet potato, carrot, broccoli, butter, kale
what are the problems of hypervitaminosis A?
altered bone metabolism and altered metabolism of other fat-soluble vitamins
what causes hypervitaminosis A?
ingesting too much preformed vitamin A from foods like liver, supplements of prescription medications
why does provitamin carotenoids not cause hypervitaminosis A ?
conversion from carotenoids to the active form of vitamin A is regulated by the body to maintain an optimum level of the vitamin. carotenoids themselves cannot produce toxicity
what are possible symptoms of hypervitaminosis A?
blurred vision, decreased appetite, drowsiness, headache, skin conditions, hypercalcemia, liver damage, cracking at corners of mouth, spontaneous fractures
how is vitamin D3 synthesized?
by UV irradiation on precursors, spontaneous rearrangement occurs. in fungi and animals
why is vitamin D not synthesized in plants?
they do not have the necessary precursors