Vitamins and Minerals Flashcards
Which vitamins are fat/lipid soluble?
ADEK — A (retinol, B-carotenes), D (cholecalciferol), E (tocopherols), K (phylloquinones, K1; menaquinones, K2)
Which vitamins are water soluble?
Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B6 Vitamin B12 Vitamin C Folate Panthotenic acid Biotin
Where are fat soluble vitamins stored?
Fat soluble vitamins can be stored in the liver or adipose tissue, water soluble vitamins: B12 and B6 can be stored
How are vitamins absorbed and transported?
Absorption is through the intestines, fat-soluble vitamins (absorption enhanced by lipids, packaged in chylomicrons —> lymphatics —> circulation)
What are the three active compounds of vitamin A?
Retinol, retinal, and retinoic acid
Where is vitamin A stored? As what?
Large amounts are stored in stellate cell of the liver (as retinylesters)
What are the sources of vitamin A?
Preformed vitamin A (animal liver products), B-carotene (dark-green, leafy vegetables)
What are the functions of vitamin A?
What’s another name for it?
Vision: retinal is part of rhodopsin in rod and cone cells
Cell signaling: retinoic acid binds to intranuclear receptors and modulates gene expression
Maintenance of epithelial integrity (protects from infections)
Spermatogenesis
Embryonic development
Another name for it is retinol
What are the two forms of vitamin A deficiency? What are the differences between the two forms?
Mild form — night blindness
Severe form — complete blindness due to aberrant differentiation (keratinization) of epithelial cells in the eye
What is the function of vitamin D?
What’s another name for it?
Increases calcium absorption from intestine, decreases renal calcium excretion, mobilizes calcium from bones
Cholecalciferol
What happens in vitamin D deficiency? How are children and adults affected differently?
Soft, pliable bones (bowed leg), children: rickets, adults: osteomalacia
What happens in vitamin D toxicity?
Loss of appetite, nausea, thirst, stupor, hypercalcinemia (calcium deposition in kidneys and arteries)
What is the function of vitamin E?
What’s another name for it?
It is the main fat-soluble antioxidant of the human body. It protects membrane-lipids from free radical damage
Tocopherols
What happens in vitamin E deficiency?
Hemolytic anemia in premature infants (tocopherol stores are not yet formed), nerve damage in older children and adults (myelin is damaged)
What is the main function of Vitamin K? What inhibits its action?
It is important for blood coagulation. Coagulation factors (II, VII, IX, X, and prothrombin), osteocalcin (a Ca2+ binding protein involved in bone formation)
Coenzyme for the synthesis of γ-carboxyglutamate residues in proteins. γ-carboxyglutamate is essential for Ca2+ binding in these proteins.
It is inhibited by Warfarin (anti-coagulant)
What are the main sources of vitamin K?
Intestinal bacteria, green leafy vegetables
What happens in the deficiency of vitamin K?
Bleeding in newborns (intestinal bacterial flora has not yet formed), newborns receive vitamin K injection at birth. Bleeding may occur in adults if bacterial flora is killed by excessive antibiotics
What is the active form of vitamin B1 (thiamine)?
Thiamine-pyrophosphate (coenzyme)
Why is pyruvate and a-ketoglutarate dehydrogenases especially important for the nervous system?
Glucose is the main energy source of the brain) — its deficiency will lead to a variety of neurological symptoms
What is beriberi? What are its two different forms? What are the differences?
Beriberi — severe thiamine deficiency
Infantile form — tachycardia, vomiting, convulsion
Adult form — dry skin, irritability, disorderly thinking, progressive paralysis
What is Wernicke-Korsakoff syndrome?
Describe its mechanism including some of its symptoms
It is a form if vitamin B1 deficiency due to chronic alcoholism
Alcohol impairs thiamine absorption from the intestines, symptoms include apathy, loss of memory, confusion, inability to move eyes
What is the function of vitamin B12 (riboflavin)?
Coenzyme in the forms of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), it is used in oxidation-reduction reactions
What happens in the event of vitamin B12 deficiency?
Cracked lips at the corner of the mouth (cheliosis), dermatitis, purple smooth tongue (glossitis)
What is the function of vitamin B3?
What’s another name for it?
Precursor for NAD and NADP (oxidation-reduction reactions), tryptophan can substitute for it
What occurs in the event of vitamin B3 deficiency?
Pellagra (4Ds — Dermatitis, Diarrhea, Dementia, Death)
How is vitamin B3 used pharmacologically?
It is used as a drug for high cholesterol treatment. Reduces lipolysis in adipose tissue. It reduces triclyceride, VLDL and LDL levels in blood
What is the function of vitamin B6?
What’s another name for it?
The active form, pyridoxal phosphate, is a coenzyme. It is used for transamination reactions, certain deamination reactions, certain decarboxylation reactions (dopamine, histamine, serotonin, GABA synthesis), and heme synthesis
Pyridoxine
Explain vitamin B6 deficiency and toxicity
Deficiency — hyperirritability, neuritis, convulsions
Toxicity — excess supplements, rare; nerve damage
How is vitamin B6 used pharmacologically?
Pharmacology — isoniazid, an anti-tuberculosis drug, depletes pyridoxal-phosphate
What is the function of vitamin C?
Collagen synthesis (proline and lysine hydroxylaton is necessary for collagen crosslinking that is dependent on vitamin C) Neurotransmitter synthesis (dopamine to norepinephrine), tyrosine degradation (4-hydroxy-phenyl pyruvate to homogentisate) Antioxidant — scavenges free radicals, ascorbic acid keeps iron in a Fe2+ state
Explain vitamin C deficiency and toxicity
Deficiency — bleeding, bruising, delayed wound healing, loose teeth, and in extreme cases, scurvy
Toxicity — intestinal problems (diarrhea)
What is the function of panthotenic acid?
Precursor of CoA
Energy production from carbohydrates
Fatty acids, amino acids, sphingolipid synthesis (palmitoyl-CoA), fatty acid and cholesterol synthesis (acetyl-CoA, malonyl-CoA), heme synthesis (succinyl-CoA)
Neurotransmitter synthesis (i.e., ACh, melatonin—acetyl-CoA)
What is the function of biotin? Explain its bioavailability
Coenzymes in carboxylation reactions, fatty acid synthesis (acetyl-CoA carboxylase), gluconeogenesis (pyruvate carboxylase), leucine degradation, propionyl CoA degradation (propionyl CoA carboxylase)
Bioavailability varies — biotin in corn and soy is readily bioavailable, only a little biotin in wheat is bioavailable
What happens to iron when it is not bound to proteins?
How is iron found in the body?
Iron is toxic, it has to be bound to proteins. Part of heme and non-heme proteins (60-80% is in hemoglobin)
Heme proteins — iron is chelated to porphyrin ring (e.g., hemoglobin)
Non-heme proteins — iron-sulphur clusters (e.g., ferredoxins) and others
Explain copper transport
Copper is transported in the circulation by ceruloplasmin (90%) and albumin (10%), it is necessary for the stability of ceruloplasmin. Both ATP7A and ATP7B deficiencies lead to low blood levels of ceruloplasmim
In Menke’s disease, what is the deficient molecule? What is defective in relation to copper? What is the treatment?
Deficient molecule is ATP7A, experiences deficient intestinal uptake of copper, neurological effects, growth retardation, hypopigmentation, laxity of skin
Treatment is copper-histidine
In Wilson disease, what is the deficient molecule? What is defective in relation to copper? What is the treatment?
Deficient molecule is ATP7B, experiences deficient excretion of copper, cirrhosis, liver failure, neurological defects, psychiatric symptoms
Treatment is copper-restricted diet, copper chelators, oral zinc tablets
What is the function of zine?
Essential for the function of a wide variety of enzymes/proteins. Oxidative phosphorylation (cytochrome c oxidase), protection against oxidative stress (Cu/Zn superoxide dismutase), acid-base balance (carbonic anhydrase), protein degradation (metalloproteases), transcription (zinc finger domain used for DNA binding)
What is the physiological role of zinc?
Wound healing, skin integrity, spermatogenesis, pancreatic function
How is zinc stored?
They are stored in metallothioneine (also binds copper with even higher affinity), high Zn levels induce metallothioneine production
What happens in the deficiency of zinc?
Acrodematitis enteropathica (deficient Zn transporter), red and inflamed patches of dry scaly skin that progress to blistered lesions, hair loss, diarrhea
What is the importance of iodine?
Thyroid hormone synthesis
What occurs in the deficiency of iodine? How are children affected?
Goiter: lack of iodine in diet (enlarged thyroid gland)
Cretinism in children: mother had limited iodine intake during pregnancy (mental and growth retardation
What is the function of selenium?
Presents mainly as selenocysteine and selenomethionine in the human body. Selenocysteine is the 21st proteinogenic amino acid (indirectly coded by the genetic code)
Enzymes containing selenium include glutathione peroxidase (antioxidant), thioredoxin reductase (antioxidant), thyroid hormone deiodinase (conversion of T4 and T3)
Explain selenium deficiency and toxicity
Deficiency — Keshan disease (China): cardiomyopathy
Toxicity — brittles nails and hair, intestinal problems, garlic-like body odor, neurological problems
