31 Questions
Which vitamins are classified as water soluble?
Folic acid, cobalamin, ascorbic acid
What is the active form of vitamin C?
Ascorbic acid
Which vitamins are classified as fat soluble?
A, D, K, E
What is the role of vitamin C in iron absorption?
Facilitates the absorption of dietary nonheme iron from the intestine by reduction of the ferric form to Fe+2
Which form of vitamin K is present in plants?
Phylloquinone (K1)
What is the principal role of vitamin K?
Posttranslational modification of proteins
What is the most active tocopherol in vitamin E?
$eta$-tocopherol
Which enzyme does warfarin inhibit in its anticoagulant mechanism?
Vitamin K epoxide reductase (VKOR)
Which vitamin is essential for vision, reproduction, growth, and maintenance of epithelial tissues?
Vitamin A
Where are fat-soluble vitamins like vitamin A carried in the body?
Chylomicrons
What is the early sign of vitamin A deficiency that makes it difficult to see in dim light?
Night blindness (nyctalopia)
What is the irreversible consequence of prolonged vitamin A deficiency?
Irreversible loss in the number of visual cells
What is the toxic syndrome called when there is excessive intake of vitamin A?
Hypervitaminosis A
What are the early signs of chronic hypervitaminosis A?
All of the above
What are the symptoms of scurvy caused by vitamin C deficiency?
Sore gums, loose teeth, fragile blood vessels, hemorrhage, swollen joints, bone changes, and fatigue
What is the role of folic acid in the body?
Facilitates the synthesis of amino acids, purine nucleotides, and thymidine monophosphate
What is a consequence of folic acid deficiency during pregnancy?
Increased risk of neural tube defects such as spina bifida and anencephaly
Where does vitamin B12 absorption primarily occur?
Ileum
What is the cause of pernicious anemia?
Severe malabsorption of vitamin B12
What is the main source of Vitamin B12?
Microorganisms
What happens in folic acid deficiency?
Folate is trapped in the N5-methyl form leading to a deficiency of the THF forms needed in purine and TMP synthesis causing megaloblastic anemia symptoms.
What are the consequences of vitamin B12 deficiency?
The accumulation of unusual (branched) fatty acids incorporated into cell membranes including those of the central nervous system.
How does folic acid deficiency affect red blood cells?
Folate is trapped in the N5-methyl form leading to a deficiency of the THF forms needed in purine and TMP synthesis causing megaloblastic anemia symptoms.
Which vitamin B is important for the formation of pyridoxal phosphate, a cofactor for various enzymes?
Vitamin B6
What can lead to sensory neuropathy at intakes above 500 mg/day?
Toxicity of Pyridoxine (Vitamin B6)
Which vitamin is important for the formation or degradation of α-ketols, and the oxidative decarboxylation of α-keto acids?
Vitamin B1
Which vitamin deficiency can lead to decreased production of ATP and impair cellular function?
Thiamine (Vitamin B1)
Which vitamin is important for the formation of nicotinamide adenine dinucleotide (NAD+) and its phosphorylated derivative, nicotinamide adenine dinucleotide phosphate (NADP+)?
(Niacin) Vitamin B3
"Wet beriberi" is associated with which vitamin deficiency?
(Thiamine) Vitamin B1
What is the main function of Riboflavin (Vitamin B2)?
Formation of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
What can induce symptoms of biotin deficiency?
Lack of raw egg white in diet
Study Notes
o Most common causes of Pernicious Anemia: Autoimmune destruction of gastric parietal cells leading to IF deficiency, and gastric surgery.
- IF deficiency impairs B12 absorption, leading to anemia and neuropsychiatric symptoms.
- Treatment includes lifelong B12 supplementation via oral or intramuscular injection.
o Pyridoxine (Vitamin B6) is important for the formation of pyridoxal phosphate, which functions as a cofactor for various enzymes.
- Dietary deficiencies are rare but can occur in infants, women on oral contraceptives, and alcoholics.
- Toxicity can lead to sensory neuropathy at intakes above 500 mg/day.
o Thiamine (Vitamin B1) is important for the formation or degradation of α-ketols, and the oxidative decarboxylation of α-keto acids.
- Thiamine deficiency can lead to decreased production of ATP, and impair cellular function.
- Symptoms include peripheral neuropathy (dry beriberi), edema (wet beriberi), and mental confusion, gait ataxia, and memory problems (Wernicke-Korsakoff syndrome).
o Niacin (Vitamin B3) is important for the formation of nicotinamide adenine dinucleotide (NAD+) and its phosphorylated derivative, nicotinamide adenine dinucleotide phosphate (NADP+).
- NAD+ and NADP+ serve as cofactors in oxidation-reduction reactions.
- Niacin can be used in the treatment of type IIb hyperlipoproteinemia.
- Deficiency can lead to pellagra, which involves the skin, gastrointestinal tract, and CNS.
o Riboflavin (Vitamin B2) is important for the formation of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD).
- FMN and FAD function as cofactors in oxidation or reduction of substrates.
- Deficiency is not associated with a major human disease.
o Biotin (Vitamin B7) is a cofactor in carboxylation reactions.
- Deficiency does not occur naturally due to its wide distribution in food and intestinal bacteria.
- Consumption of raw egg white can induce symptoms of biotin deficiency.
o Pantothenic Acid (Vitamin B5) is a component of coenzyme A, and is important for the transfer of acyl groups.
- Deficiency is not well characterized in humans.
Test your knowledge of the most common causes and treatment of pernicious anemia, including autoimmune destruction of gastric parietal cells, cobalamin deficiency, anemia, and neuropsychiatric symptoms. Learn about the importance of early treatment to prevent irreversible CNS effects.
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