Vitamin B12 and B6 Deficiency

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Questions and Answers

Which type of vitamins can be readily excreted in the urine?

Water soluble vitamins

What is the active form of vitamin C?

Ascorbic acid

Which type of vitamins is stored in significant quantities in the liver and adipose tissue?

Fat soluble vitamins

Which vitamin facilitates the absorption of dietary nonheme iron from the intestine?

Vitamin C Signup and view all the answers

Which vitamin is required in the hepatic synthesis of the blood clotting proteins prothrombin, factor VII, factor IX, and factor X?

Vitamin K Signup and view all the answers

Which vitamin functions as an antioxidant in the prevention of nonenzymic oxidations, such as the oxidation of LDL?

Vitamin E Signup and view all the answers

Which vitamin is responsible for regenerating the active form of vitamin E?

Vitamin C Signup and view all the answers

Which molecule is the active form of Vitamin D?

Calcitriol Signup and view all the answers

How is Vitamin A transported to peripheral tissues from the liver?

Retinol-binding protein and transthyretin Signup and view all the answers

What is the consequence of excessive intake of Vitamin A?

Hypervitaminosis A with dry skin and liver damage Signup and view all the answers

Which vitamin is synthesized by gut microbiota?

Vitamin K Signup and view all the answers

What is the primary role of Vitamin K?

Posttranslational modification of proteins involved in blood clotting Signup and view all the answers

Which condition can result from Vitamin A deficiency?

Night blindness and irreversible loss of visual cells Signup and view all the answers

What is the storage site for retinyl esters?

Liver Signup and view all the answers

Which molecule binds to intracellular receptor proteins to regulate transcription in target cells for Vitamin A?

Retinol Signup and view all the answers

What are the consequences of Vitamin D deficiency?

Nutritional rickets and osteomalacia Signup and view all the answers

What occurs when Vitamin D binds to intracellular receptor proteins in target cells?

It regulates serum calcium and phosphorus levels Signup and view all the answers

What happens when retinol is oxidized to retinoic acid?

It binds to specific receptor proteins and regulates RNA synthesis Signup and view all the answers

Which vitamin deficiency can lead to anemia and neuropsychiatric symptoms?

Vitamin B12 Signup and view all the answers

What is the primary form of Pyridoxine?

Pyridoxine Signup and view all the answers

At what intake level can toxicity with neurologic symptoms occur for Pyridoxine?

500 mg/day Signup and view all the answers

Which vitamin deficiency results in diseases like beriberi and Wernicke-Korsakoff syndrome?

Vitamin B1 Signup and view all the answers

What are the cofactors produced by Niacin, or Vitamin B3?

NAD+ and NADP+ Signup and view all the answers

What are the products formed by Riboflavin, or Vitamin B2, through the addition of adenosine monophosphate?

FMN and FADH2 Signup and view all the answers

Which vitamin deficiency can result in symptoms like dermatitis, hair loss, loss of appetite, and nausea?

Vitamin B7 Signup and view all the answers

What is the primary function of Pantothenic acid in the human body?

Coenzyme A component Signup and view all the answers

What is the disease characterized by sore and spongy gums, loose teeth, fragile blood vessels, hemorrhage, swollen joints, bone changes, and fatigue?

Scurvy Signup and view all the answers

What is the characteristic of folic acid deficiency that causes an inability to divide due to the production of large, immature RBC precursors?

Megaloblastic anemia Signup and view all the answers

What is the main role of vitamin B12 in enzymatic reactions?

Re-methylation of homocysteine to methionine Signup and view all the answers

In which part of the body does vitamin B12 absorption occur?

Small intestine Signup and view all the answers

What causes megaloblastic anemia due to vitamin B12 deficiency?

Impaired utilization of N5-methyl folate Signup and view all the answers

What is the common cause of vitamin B12 deficiency among individuals?

Restricted intake (vegan diet) Signup and view all the answers

What causes pernicious anemia, a severe form of vitamin B12 deficiency?

Autoimmune destruction of the gastric parietal cells Signup and view all the answers

Which nutrient plays a key role in one-carbon metabolism and serves as a cofactor for the synthesis of purines, thymidylate, and methionine?

Folic acid Signup and view all the answers

What is the main characteristic feature of scurvy caused by vitamin C deficiency?

Fragile blood vessels and hemorrhage Signup and view all the answers

Which condition is common among pregnant women and individuals with alcoholism due to its deficiency causing neural tube defects in developing fetuses?

Folic acid deficiency Signup and view all the answers

What is the main source of vitamin B12?

Meat and animal-derived products Signup and view all the answers

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Study Notes

Vitamin C deficiency leads to scurvy, a disease characterized by sore and spongy gums, loose teeth, fragile blood vessels, hemorrhage, swollen joints, bone changes, and fatigue.
Decreased hydroxylation of collagen in scurvy results in defective connective tissue.
Folic acid plays a key role in one-carbon metabolism and serves as a cofactor for the synthesis of purines, thymidylate, and methionine.
Folic acid deficiency causes megaloblastic anemia, which is characterized by the production of large, immature RBC precursors that cannot make DNA, leading to an inability to divide.
Folic acid deficiency is common among pregnant women and individuals with alcoholism, and it can lead to neural tube defects in developing fetuses.
Vitamin B12 is necessary for two important enzymatic reactions: the re-methylation of homocysteine to methionine and the isomerization of methyl-malonyl coenzyme A.
Vitamin B12 deficiency results in an impaired utilization of N5-methyl folate in the methylation of homocysteine, causing folate to be trapped in the N5-methyl form and leading to megaloblastic anemia.
Vitamin B12 deficiency causes an accumulation of unusual fatty acids in cell membranes, particularly in the central nervous system, leading to neurological manifestations.
Vitamin B12 is synthesized only by microorganisms and is found in animal-derived foods such as liver, red meat, fish, eggs, dairy products, and fortified cereals.
Vitamin B12 deficiency is most commonly seen in individuals who fail to absorb the vitamin from their diet.
Factors that can cause vitamin B12 deficiency include restricted intake (vegan diet), increased demand (pregnancy, bleeding, lactation), pernicious anemia (IF deficiency), and malabsorption problems (Crohn's disease, celiac disease, and gastric bypass surgery).
Vitamin B12 absorption occurs in the ileum, where it binds to a receptor (cubilin) and is taken up into mucosal cells, where it is transported into the general circulation and stored in the liver.
Pernicious anemia is a severe form of vitamin B12 deficiency caused by an autoimmune destruction of the gastric parietal cells responsible for the synthesis of IF, preventing the absorption of vitamin B12.