Vandopløselige vitaminer/ Flashcards
Kap 11
How many water soluble vitamins are there?
- 9 (8 B-vitamins, 1 C vitamin)
- all b-vitamins are a part of the metabolism
What is the definition of vitamins?
- organic compounds needed for growth
- something we cant synthesize ourselves
- Needed in very small amount
- Co-factors
- Not a source of calories
Thiamin diphosphat is a coenzyme for which enzymes in metabolic pathways?
Thiamine diphosphate (B1 vitamer) er coenzym for:
- Pyruvat dehydrogenase
- alpha-ketoglutarate dehydrogenase
- Keto acid dehydrogenase
- Transketolase in PPP
Which diseases are related to B1 deficiency?
- Dry beriberi
- Generally too little acetyl CoA and too much lactate and pyruvate
- Acidosis
Vitamin B2, riboflavin, is a component in which two flavocoenzymes?
- Riboflavin monophosphate (FMN)
- Flavin adenine dinucleotide (FAD)
Which diseases is related to B2 deficiency?
ariboflavinosis
What is niacin?
- Vitamin B3
- Not strictly a vitamin but acts as one
- Can be synthesized in the body from tryptophan
- Necessary for protein and fat metabolism, healthy skin, gastrointestinal and CNS function, production of sex hormones
What are sources of niacin?
Enriched grains cereal, beef, turkey, fish, asparagus, peanuts
Also in corn, but bound by a protein, so should be soaked in water
Which diseases are related to Niacin deficiency?
- pellagra
- lack of extracting energi from protein
Mention a vitamin C
ascorbat
Can humans and other primates synthesize ascorbat (vitamin C)?
No, because of multiple mutations in the gene encoding gulonolactone oxidase
Where is vitamin C taken up in the body?
In The jejunum via the intestinal brush border and buccal mucosa
What are the functions of vitamin C?
- Reduces Fe3+ to Fe2+
- Proline- and lysine hydroxylases (coenzym til dem)
- Dannelse af hydroxyproline (collagen dannelse)
- Reduces Cu2+ til Cu+
- Antioxidant
Which diseases are linked with vitamin C deficiency?
Scurvy (skørbug??),
needed to organize collagen fiber (in skin, teeth and bone)
Which vitamin contains a metal, and which metal?
B12
metal = cobalt
- is in foods of animal origin
How is vitamin B12 released from the food?
by gastric acid, pepsin and duodenal enzymes together with intrinsic factor
What are some of the important roles of vitamin B12?
Required as coenzyme for:
- Isomerization of L-methylmalonyl CoA to succinyl CoA. (important for hemoglobin synthesis)
- Methylation of homocysteine to methionine. (important in intracellular synthesis of folate coenzyme)
Where is B12 absorbed in the body?
- in the ileum as an active process
- intrinsic factor (IF) is needed for uptake in the ileum, in a 1:1 ratio
- Required Calcium ions and neutral pH
How much vitamin B12 does the body store?
Normally 3-4 mg
Stored in the liver
Sufficient for approx. 3 years of no extra B12
Vitamin B12 deficiency can be caused by?
- Inadequate dietary intake
Vegans eg. - Intestinal malabsorption. Commonly due to lack of intrinsic factor gastrointestinal disease
Where are the folates absorbed?
in the upper jejunum
When is folate especially important?
In early pregnancy
What vitamins are parts of electron carriers?
Flavin in FADH
Niacinamid in NADH/NADPH
Hvilket vitamin er pyridoxal phosphat?
Vitamin B6
Vitamin B6/pyridoxal phosphat is a coenzyme in what three areas of metabolism?
- Biosynthesis of amino acids
- Cofactor for glycogen phosphorylase
- Regulation of steorid hormone action
What functions are biotin/B7 essential for?
- Cell growth
- Fatty acid synthesis
- metabolism of fatty acids and amino acids
Biotin/B7 deficiency is non existing, except for people who…?
- Eat many raw eggs (avidin binds biotin)
Pantothenic acid kaldes også vitamin B5, og er en del af hvilket vigtigt molekyle?
Coenzyme A
Which vitamin is this?
Thiamin / vitamin B1
Which vitamin?
Riboflavin / B2
Which vitamin?
Vitamin C / ascorbic acid
Which vitamin?
Pyridoxal phosphate / Vitamin B6
Which vitamin?
Pantothenic acid / Vitamin B5
Which vitamin and alternative form is seen here?
Top: Nicotinamid
Bottom: Nicotinic acid/niacin
Which vitamin?
Folate. (Folic acid på billede)
Which vitamin?
Biotin / Vitamin B7
Which vitamin?
B12
Transcobalamines transports which vitamin in the plasma?
Transport Vitamin B12 in a 1:1 ratio complex.
Binds to developing blood cells in the bone marrow and releases B12.
Which vitamin is a carbon donor/acceptor in the following reactions?
- Synthesis of methionine
- Synthesis of nucleotides
- Serin to glycin conversion
- Histidin catabolism
Folate (B9)
What are characteristics of water-soluble vitamins?
- Dissolve in water
- carried in blood, not stored
- Found in vegetables, fruit, grains milk and meat
Hvordan optages og udskilles vitamin B6/pyridoxal phosphat?
- Vitamerer hydroliseres af alkaline phosphatase i tarm mucosa
- Leveren udskiller vitaminet bundet til albumin
What water-soluble vitamins can the gut microbiome synthesise?
Thiamin, riboflavin, nicotinic acid, biotin and folate.
(B1, B2, B3, B7 og B9)
(gælder ikke som at kroppen selv kan syntetisere dem)
Which vitamins can the body synthesise?
Vitamin D (fra solen, laves igennem huden)
Niacin (B3), omdannes fra tryptofan
Kan man generelt få for meget af vandopløselige vitaminer?
Nej, når plasma-koncentrationen er højere end behovet udskilles vitaminerne i urinen
