Solution to Multiple choice questions- Vitamins

Q.1) The active coenzyme form of Cobalamine is-
a) Methyl cobalamine                                    
b) Deoxyadenosyl cobalamine
c) Both of the above                                    
d) none of the above          
(c)
2) All are one carbon donors except-
a) Serine                                                    
b)S- Adenosyl Methionine
c) Choline                                                    
d)Thiamine                        
(d)
3) All are needed as coenzyme for alpha keto glutarate dehydrogenase complex except-
a) Niacin                                                    
  b)Folic acid
c) Riboflavin                                              
d) Lipoic acid                      
(b)
4) Which of the following vitamins can act without phosphorylation-?
a) Pyridoxine                                              
b) Lipoamide
c) Niacin                                                    
d)Thiamine                        
(b)                      
5)  Impaired Thymidylate formation is due to the deficiency of-
a) Pantothenic acid                                      
b) Niacin
c) Folic acid                                                
d) B12                              
(c)                    
6) Scurvy is due to impaired———— synthesis
a) Collagen                                                
b)Prothrombin
c) Hemoglobin                                            
d) Elastin                            
(a)                            
7) Epileptiform convulsions in infants are found in the deficiency of-
a) Riboflavin                                              
b) Thiamine
c) Niacin                                                    
d)Pyridoxine                    
(d)
8) Pantothenic acid is important for which of the following steps or pathways?
a) Pyruvate carboxylase                              
b)Fatty acid synthesis
c)Gluconeogenesis                                    
d)Glycolysis                      
(b)                  
9) The yellow color of egg yolk is due to the presence of –
a) Riboflavin                                                
b) Thiamine
c) Niacin                                                      
d)Pyridoxine                      
(a)                
10) Neurological manifestations are present in-
a) Dry Beri- Beri                                          
b) B6 deficiency
c) B12 deficiency                                          
d) all of the above            
(d)        
11) Transketolase activity is measured for the detection of————- deficiency
a) Riboflavin                                                
b) Thiamine
c) Niacin                                                    
d)Ascorbic acid              
(b)        
12) All are the synonyms of Folic acid except-
a) Vitamin M                                                
b) Vitamin Bc
c) PGA                                                        
d) Vitamin S                    
(d)        
13)  Schilling test is done to detect the deficiency of-
a) Riboflavin                                              
b) B12
c) Niacin                                                    
d)Biotin                            
(b)          
14) Sub Acute Combined Degeneration of the Spinal Cord is found in the  deficiency of-
a) B12                                                        
b)B6
c) Niacin                                                    
d)Pyridoxine                  
(a)              
15) The Transaminases  require the presence of-
a) Inositol                                                  
b)B6
c) B12                                                        
d)B2                              
(b)                  
16)The active coenzyme form of Vitamin D is-
a) Calcidiol                                                
b) Calcitriol
c) Calcitetrol                                              
d) none of the above        
(b)
17) All are one carbon compounds except-
a) Formyl                                                  
b)Methyl
c) Methylene                                              
d) CO                            
(d)              
18) Which of the following vitamins is an integral component of coenzyme A  that allows two carbon units to enter the TCA cycle?
a) Thiamine                                                
b)Pantothenic acid
c) Biotin                                                      
d)Vitamin A                  
(b)          
19) Sideroblastic anemia occurs due to the deficiency of vitamin-
a) B6                                                          
b)B12
c) B3                                                          
d)B1                              
(a)                      
20)  Homocystinuria is due to the deficiency of-
a)Vitamin B12                                            
b) B6
c) Folic acid                                                
d) All of the above            
(d)
21) Which one of the followings must be utilized during the conversion of Acetyl co A to Malonyl co A
a) Thiamine pyrophosphate                        
b) Acyl carrier protein
c) Biotin                                                    
d)Niacin                        
c)                
22) Wernicke’sEncephalopathy is found in the deficiency of-
a) Riboflavin                                                
b) Thiamine
c) Niacin                                                    
d)Pyridoxine                
(b)
23) Ascorbic acid is required for the utilization of all except-
a) Phenylalanine                                          
b) Tryptophan
c)Tyrosine                                                  
d)Proline                      
(d)            
24) The egg white injury is due to the induced deficiency of –
a) Riboflavin                                                
b) Thiamine
c) Niacin                                                    
d)biotin                        
(d)              
25)  Which of the following statements describing vitamin K is true?
a) Vitamin K is degraded by intestinal bacteria
b) It is obtained by eating citrus fruits
c) It is required for the synthesis of prothrombin              
d) It prevents thrombosis.                                                            
(c)                                                        
26) Intra dermal dye Test is done for the detection of ————-deficiency
a) Riboflavin                                              
b) Thiamine
c) Niacin                                                    
d)Ascorbic acid            
( d)      
27) The Deaminase enzyme requires the presence of-
a) Inositol                                                  
b)B6
c) B12                                                        
d)B2                            
(b)                                            
28)Which vitamin is required for almost all aspects of protein and amino acid metabolism?
a) Vitamin B6                                              
b) Vitamin B12
c) Vitamin C                                                
d) Vitamin B3                
(a)  
29) Which vitamin is required for the absorption of calcium from the gut?
a) Vitamin D                                                
b) Vitamin E
c) Vitamin B12                                            
d)Vitamin K                  
(a)            
30) Out of the followings  which vitamin increases the absorption of iron from the gut?
a) Vitamin D                                                
b) Vitamin E
c) Vitamin C                                                
d)Vitamin K                  
(c)  
31) Which of the following enzymes  does not require a phosphorylated form of coenzyme?
a) Glucose-6-phosphatase                            
b) Pyruvatedehydrogenase
c) Transketolase                                          
d) Transaminase            
(a)
32) Which essential nutrient participates as a coenzyme in the transport of high energy electrons and H+ ions during oxidative phosphorylation in the mitochondrion?
a) Riboflavin                                                
b) Thiamine
c) Niacin                                                    
d)Ascorbic acid            
(a and c)
33) A 2-year- old child presents with chronic cough, bronchitis, growth failure, chronic diarrhea and growth failure. A deficiency of which of the following vitamins should be considered?
a) Vitamin A                                                
b) Vitamin C
c) Vitamin B2                                              
d) Vitamin E                  
(a)                
34) A homeless person is brought in to the emergency room with psychotic illness and smell of alcohol in his breath. Which of the following is needed as part of the treatment?
a) Glucose                                                
b)Niacin
c) Thiamin                                                  
d)Riboflavin                    
(c)
35) The enzyme Ribonucleotide Reductase requires the presence of-
a) Inositol                                                    
b)B1
c) B12                                                        
d)B2                            
(c)                      
36) Signs of vitamin C deficiency include all except-
a) Bruises                                                  
b)Tooth loss
c) Bony fractures                                        
d) Liver failure              
(d)
37) All are signs of niacin deficiency except-
a) Hair loss                                                
b) Diarrhea
c) Dementia                                                
d)Dermatitis                  
(a)
38) Choose the odd one out-
a) Retinol                                                    
b)Ascorbic acid
c) Cholecalciferol                                        
d) Tocopherol                
(b)
39) Deficiency of which of the following vitamins does not cause fatty liver?
a) Vitamin C                                                
b) Vitamin E
c) Cholecalciferol                                        
d) Vitamin A                    
(c)
40) Which out of the following vitamins in PDH complex becomes non functional by Arsenate poisoning?
a) Niacin                                                    
b)Pantothenic acid
c) Lipoamide                                              
d) Riboflavin                  
(c)
41) Excessive consumption of beta-carotene can result in:
a) Toxicity leading to headaches, hair loss and dry skin
b) Renal failure
c) Yellow appearance to the skin
d) Mineralization of soft tissues such as the lungs and kidneys              
(c)
42) Which of the following nutrients, if taken in excess during pregnancy,can cause birth defects?
a) Vitamin A                                                
b)Vitamin C
c) Vitamin D                                                
d)Vitamin E                  
(a)
43) As a hormone, vitamin D has three target tissues. Which are they?
a) Kidney, small intestine, bone                    
b)Heart, blood, bone marrow
c)Kidney, liver, brain                                  
d)Small intestine, liver, fat cells  
(a)
44)  Which of the following vitamins serves an antioxidant function and has a relation to selenium metabolism
a) Vitamin A                                                
b) Vitamin C
c)Vitamin D                                                
d)Vitamin E                    
(d)
45) Which of the following conditions does not rapidly produces a functional deficiency of vitamin K?
a) Warfarin therapy to prevent thrombosis in patients prone to Thrombus formation
b) broad-spectrum antibiotic therapy
c)  Lack of citrus fruit in the diet
d) Premature birth                                                                              
(c)
46) Which one of the followings is a coenzyme, the deficiency of which can cause Folate trap?
a) Methyl Cobalamine                                  
b) Tetrahydrofolate
c) Copper                                                    
d)Biotin                        
(a)
47) A deficiency of which of the following vitamins is associated with neural tube defects-
a) Ascorbic acid                                          
b) Folic acid
c) Nicotinic acid                                          
d)Pantothenic acid            
(b)
48) Which of the following is a coenzyme?
a) Glucose-6-phosphate                              
b) Glucose-1-phosphate
c) Lipoic acid                                              
d) UDP-Glucose            
(c)
49) Which one of the following transfer acyl groups?  
a) Thiamine pyrophosphate                        
b)Lipoamide
c) NADH                                                  
d)FADH2                      
(b)
50) The coenzyme derived from Riboflavin is required by which of the following enzymes?
a) Lactate dehydrogenase                          
b)Glutamate dehydrogenase
c) Acyl co A dehydrogenase                    
d) Malate dehydrogenase
(c)


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One Word Answer Type Questions- Choose the correct answer-Vitamins-set -1(Unsolved)

1) Methyl Malonic aciduria is associated with vitamin B6/ B12 deficiency.

 2) Glycogen synthesis/ degradation requires Vitamin B6.        

3) Carboxylation/Decarboxylation reactions require Biotin.  

4) In Vitamin B12 deficiency Folate is trapped in the demethylated/methylated form.                                                                                        

5) The coenzyme form of pyridoxine is Pyridoxal phosphate/ Pyridoxol phosphate.                                                                                                                                  

 6) Hydroxylation/Dehydrogenation reactions require riboflavin.    

7) Pellagra is associated with deficiency of B1/ B3.                

8) The Dehydro/Hydroxylated form is the active form of ascorbic acid.

9) Methotrexate competitively inhibits synthesis of reduced form of Niacin/ Folic acid.                                                                                                      

10) Xanthurenic acid test is for theassessment of B6/ Folic aciddeficiency

11) Intrinsic factor is required for the absorption of vitamin B6/ B12

12) Menadione/ Menaquinone is a synthetic form of vitamin K

13) Carboxylation/Decarboxylation reactions require B6.      

14) The absorbable form of Thiamine is Free Thiamine/TPP      

15) Hydroxylation/Dehydrogenation reactions require Ascorbic acid.        

16) Pellagra is precipitated by the deficiency of B1/ B6.          

17) The Dehydro/ Reduced form is the active form of Folic acid.

18) Alcohol inhibits the absorption of Thiamine/vitamin A.      

19) Histidine loading test is for the assessment of B6/ Folic acid deficiency

20) Achlorhydria can cause vitamin B6/ B12 deficiency          

21) Haem synthesis/ degradation requires Vitamin B6              

22) Carboxylation of Glutamic acid residuesrequires vitamin K/Biotin during the process of coagulation.                                                              

23) Reduction/ Dehydrogenation reactions require NADPH  

24) Lactic acidosis is associated with deficiency of B1/ B3.      

25) “Burning feet syndrome” is a feature of niacin/Pantothenic acid deficiency.

26) Sulphonamides competitively inhibit synthesis of Niacin/ Folic acid.

27) Retinol/retinoic acid is required for the regulation of gene expression and tissue differentiation.

28) 11-cis Retinal/11-cis Retinol is required for vision.          



Q.B-Name the coenzyme for each of the following reactions-

1)Pyruvate——————————–>Lactate.                                            

2) Pyruvate——————————–>Oxaloacetate.                                  

3) Pyruvate———————————>Alanine.                                            

4)Pyruvate———————————>Malate.                                                    

5)Lysine————————————->Hydroxy Lysine.                              

6) Glutamic acid————————- —>.Gamma Carboxy Glutamic acid  

7) Malate———————————–>Oxaloacetate.                                          

8) Glutamate——————————–>Alpha keto glutarate.                        

9) Succinate ——————————->Fumarate.                                          

10) Tyrosine——————————–>Tyramine.                              

11) Homocysteine————————>Methionine.                                    

12) L- Methyl Malonyl coA————> Succinyl co A.


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Q. A- State true or false

1) The neonates treated by phototherapy for jaundice can develop riboflavin deficiency.

2) Pantothenic acid deficiency affects fatty acid synthesis.              

3) Biotin is a sulfur containing vitamin.                                

4) Vitamin B12 can be stored in liver.                                      

5) Folic acid is required for the propagation of the nerve impulse.      

6)The patients treated by Isoniazid for tuberculosis can have pellagra like rashes on the body.                                                                          

7) The utilization of Tyrosine requires the presence of vitamin C.    

8) More the protein intake more is the requirement of Thiamine.    

9)Niacin deficiency can precipitate B6 deficiency.                  

10)Folic acid is a one carbon carrier in the body.                  

11)A pure vegetarian diet can produce vitamin B12 deficiency.      

12) Pantothenic acid deficiency leads to fatty liver formation.

13) Folic acid is a sulfur containing vitamin.                                  

14)Vitamin A is stored in the liver.                                      

15)Defective myelin sheath formation occurs in B12 deficiency.    

16) The morning sickness of pregnancy can be treated by Vitamin B6.

17) L- Amino acid oxidases require the presence of vitamin C.

18)More the carbohydrate intake more is the requirement of Thiamine.  

19) Renal failure can precipitate vitamin D deficiency.                      

20) Vitamin E is an antioxidant in the body.                            

21) Isolated Riboflavin deficiency is not commonly encountered.      

22) Total non vegetarian diet can produce scurvy.                          

23) Pantothenic acid deficiency affects fatty acid degradation.        

24) Niacin can increase HDL levels    .                                  

25) Folic acid can be stored in the liver.                                          

26) Thiamine is required for the propagation of the nerve impulses.

27) In addition to its coenzyme role, Riboflavin is the source of ADP-ribose for the ADP-ribosylation of proteins.                                                        

28) Some 60 mg of dietary niacin is equivalent to 1 mg of tryptophan.

29) Thiamine nutritional status can be assessed by erythrocyte Glutathione reductase activation.                                                                                    

30) The intestinal activity of carotene dioxygenase is fast, so that a negligible proportion of ingested beta -carotene may appear in the circulation unchanged.                                                  

Q.B-Name the deficiency disorder/ clinical manifestations of deficiency of each of the vitamins mentioned below-

    1)   Niacin

    2)   Pyridoxine

    3)   Biotin

    4)   Thiamine

    5)   VitaminB12

    6)   Folic acid

    7)   Vitamin A

    8)   Vitamin K

   9)Riboflavin

   10) Vitamin D

Q.C- Give at least one therapeutic use of each of the vitamins mentioned   below-

    1)Niacin

   2)Pyridoxine

   3)Vitamin C

 4) Biotin

 5) Thiamine

 6) Vitamin B12

 7) Folic acid

 8) Pantothenic acid

9) Vitamin K

  10)Riboflavin

  11)Vitamin A

  12)Vitamin D


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Solution to One Word Answer Type Questions- Vitamins-set -1(Choose the correct answer)

1)Methyl Malonic aciduria is associated with vitamin B6/ B12 deficiency.

(B12)

2) Glycogen synthesis/ degradation requires Vitamin B6.  

(Degradation)    

3) Carboxylation/ Decarboxylation reactions require Biotin.

(Carboxylation)

4) In Vitamin B12 deficiency Folate is trapped in the demethylated/methylated form.                                                    

(Methylated)

5) The coenzyme form of pyridoxine is Pyridoxal phosphate/Pyridoxol phosphate.      

(Pyridoxal phosphate)                              

6) Hydroxylation/ Dehydrogenation reactions require riboflavin.

(Dehydrogenation)  

7) Pellagra is associated with deficiency of B1/ B3.

(B3)          

8) The Dehydro/ Hydroxylated form is the active form of ascorbic acid.

 (Dehydro)

9) Methotrexate competitively inhibits synthesis of reduced form of Niacin/ Folic acid.                                                                

(Folic acid)                                                                                            

10) Xanthurenic acid test is for the assessment of B6/ Folic acid deficiency

(B6 deficiency)

11)  Intrinsic factor is required for the absorption of vitamin B6/B12

(B12)

12) Menadione / Menaquinone is a synthetic form of vitamin K

(Menadione)

13) Carboxylation/ Decarboxylation reactions require B6.

((Decarboxylation)  

14) The absorbable form of Thiamine is Free Thiamine/TPP

(Free Thiamine)  

15) Hydroxylation/ Dehydrogenation reactions require Ascorbic acid.

(Hydroxylation)        

16) Pellagra is precipitated by the deficiency of B1/B6.

(B6)    

17) The Dehydro/ Reduced form is the active form of Folic acid.

(Reduced)

18) Alcohol inhibits the absorption of Thiamine/vitamin A.

(Thiamine)    

19) Histidine loading test is for the assessment of B6/ Folic acid deficiency

(B6)

20) Achlorhydria can cause vitamin B6/ B12 deficiency    

(B12)      

 21) Heme synthesis/ degradation requires VitaminB6  

(Synthesis)            

 22) Carboxylation of Glutamic acid residues requires vitamin K/Biotin during the process of coagulation.                                      

(Vitamin K)

23) Reduction / Dehydrogenation reactions require NADPH

(Reduction)

24) Lactic acidosis is associated with deficiency of B1/ B3.  

(B1)

25) “Burning feet syndrome” is a feature of niacin/Pantothenic acid deficiency.

(Pantothenic acid)

26) Sulphonamides competitively inhibit synthesis of Niacin/Folic acid.

(Folic acid)

27) Retinol/ retinoic acid is required for the regulation of gene expression and tissue differentiation.

(Retinoic acid)

28) 11-cisRetinal/11-cis Retinol is required for vision.    

(11-cis Retinal)      

Q.B- Name the coenzyme for each of the following reactions-

1)Pyruvate——————————->Lactate.  

 (Niacin-NAD+)

2)Pyruvate——————————–> Oxaloacetate.

(Biotin)                                

3)Pyruvate———————————>Alanine.  

  (Pyridoxal phosphate-B6P)                                        

4)Pyruvate———————————>Malate.

 (Niacin-NADP+)                                                  

5) Lysine————————————->HydroxyLysine.

(VitaminC)                              

6) Glutamicacid————————->.Gamma Carboxy Glutamic acid

   (Vitamin K)

7)Malate Oxaloacetate.  

8)Glutamate——————————–>Alpha keto glutarate.

 (NAD+ or NADP+)                      

9) Succinate——————————->Fumarate.  

   (Riboflavin-FAD)                                  

10)Tyrosine——————————–>Tyramine.                              

   (Pyridoxal phosphate-B6 P)

11)Homocysteine————————> Methionine.

  (Vitamin B12 and Folic acid)                                  

12) L- Methyl Malonyl coA————> Succinyl co A.  

 (Vitamin B12)            


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Q. A- State true or false

Q. A- State true or false

1) The neonates treated by phototherapy for jaundice can develop riboflavin deficiency.                                                              

(True)

2) Pantothenic acid deficiency affects fatty acid synthesis.           

(True)

3) Biotin is a sulfur containing vitamin.                             

(True)

4) Vitamin B12 can be stored in liver.    

 (True)                             

 5) Folic acid is required for the propagation of the nerve impulse. 

 (False)

6) The patients treated by Isoniazid for tuberculosis can have pellagra like rashes on the body.                                                                    

(True)       

7) The utilization of Tyrosine requires the presence of vitamin C.  

 (True)

8) More the protein intake more is the requirement of Thiamine.

(False)

9) Niacin deficiency can precipitate B6 deficiency.    

(False)         

10) Folic acid is a one carbon carrier in the body.                        

(True)

11) A pure vegetarian diet can produce vitamin B12 deficiency.

(True)

12) Pantothenic acid deficiency leads to fatty liver formation.       

 (True)

13) Folic acid is a sulfur containing vitamin.   

(False)                   

14) Vitamin A is stored in the liver.      

(True)                             

15) Defective myelin sheath formation occurs in B12 deficiency.

(True)         

16) The morning sickness of pregnancy can be treated by Vitamin B6.

(True)

17) L- Amino acid oxidases require the presence of vitamin C.

(False)

18) More the carbohydrate intake more is the requirement of Thiamine. 

(True)

19) Renal failure can precipitate vitamin D deficiency.      

(True)          

20) Vitamin E is an antioxidant in the body.   

(True)                   

21) Isolated Riboflavin deficiency is not commonly encountered.  

(True)

22) Total non vegetarian diet can produce scurvy.

(True)                             

23) Pantothenic acid deficiency affects fatty acid degradation.     

(True)

24) Niacin can increase HDL levels  

(True).                                      

25) Folic acid can be stored in the liver.

(False)                                      

26) Thiamine is required for the propagation of the nerve impulses.

(True)

27) In addition to its coenzyme role, Riboflavin is the source of ADP-ribose for the ADP-ribosylation of proteins.                                

(False) 

28) Some 60 mg of dietary niacin is equivalent to 1 mg of tryptophan.

 (False)

29) Thiamine Nutritional Status Can Be Assessed by Erythrocyte Glutathione Reductase Activation.                                                           

(False)   

30) The intestinal activity of carotene dioxygenase is fast, so that a negligible proportion of ingested beta -carotene may appear in the circulation unchanged.                                                

(False)

Q.B- Name the deficiency disorder/ clinical manifestations of deficiency of each of the vitamins mentioned below

1) Niacin - Pellagra- photosensitive dermatitis, depressive psychosis and diarrhea

        2) Pyridoxine - Neurological manifestations (No specific disease), convulsions

3)  Biotin- Hair loss, Dermatitis (No specific disease)

        4)  Thiamine—Beri-Beri, or central nervous system lesions (Wernicke-Korsakoff syndrome)

        5) Vitamin B12- Megaloblastic anemia, Sub acute combined degeneration of spinal cord

        6)  Folic acid- Megaloblastic anemia

        7)   Vitamin A Night blindness, xerophthalmia;keratinization of skin

        8)   Vitamin K - Impaired blood clotting, hemorrhagic diseases

        9) Riboflavin- Glossitis, Cheilosis, dermatitis

10) Vitamin D- Rickets in children; osteomalacia in adults

 Q.C- Give at least one therapeutic use of each of the vitamins mentioned below-

 1)Niacin- Niacin is specific in the treatment of Glossitis, dermatitis and the mental symptoms seen in pellagra.

 High doses of nicotinic acid (1.5-4 g/day)can reduce total and low-density lipoprotein cholesterol and triacylglycerols and increase high-density lipoprotein cholesterol in patients at risk of cardiovascular disease.

 2)Pyridoxine- Sideroblastic anemia and pyridoxine-dependent abnormalities of metabolism, for relieving the symptoms of PMS (premenstrual syndrome), treatment of nausea and vomiting during pregnancy (hyperemesis gravidarum), relief of depression and neurological symptoms.  Also given for the prevention of IHD  and potentiation of immune functions.

 3) Vitamin C- for the prevention of IHD, cancers, to promote healingof wounds and treatment of common cold.

 4) Biotin-Biotin is used clinically to treat the biotin-responsive inborn errors of metabolism, holocarboxylase synthetase deficiency and biotinidase deficiency. Also given for strengthening hair, nails and to combat premature graying of hair,

 5) Thiamine- treatment of beriberi and other manifestations of vitamin B1 deficiency (e.g. Wernicke-Korsakoff, peripheral neuritis),beneficial in neuritis accompanied by excessive alcohol consumption or pregnancy.

 6) Vitamin B12- For the treatment of megaloblastic anemia,hyperhomocysteinemia and prevention of cancers

 7) Folic acid- To treat megaloblastic anemia, to prevent neural tube defects given to pregnant females, to prevent IHD and for the prevention of cancers.

 8) Pantothenic acid- For the treatment of deficiency, to treat various liver conditions, arthritis, and constipation in the elderly; to prevent urinary retention after surgery or childbirth; and (together with biotin) to prevent baldness. It has also been reported to have a protective effect against radiation sickness.

9) Vitamin K- Vitamin K1 is used in the treatment of hypoprothrombinemia (low amounts of prothrombin), secondary to factors limiting absorption or synthesis of vitamin K. During operations in which bleeding is expected to be a problem, for example, in gallbladder surgery, vitamin K1 is administered.  
Anticoagulants inhibit vitamin K recycling,which can be corrected rapidly and effectively by the administration of vitaminK1. 
Vitamin K1 is often given to mothers before delivery and to newborn infants to protect against intracranial haemorrhage.

10) Riboflavin- for the prevention of deficiency in high risk groups.Riboflavin deficiency leads to decreased glutathione reductase activity, which can result in cataracts. Therefore, riboflavin is used in combination with  other antioxidants, like vitamin C and carotenoids, in disease prevention forage-related cataracts.

 11) Vitamin A- vitamin A supplementation is given to children aged over 6 months for the prevention of vitamin A deficiency. Natural and synthetic vitamin A analogues have been used to treat psoriasis and severe acne.

 12) Vitamin D- given for the treatment of rickets, prevention of osteoporosis and vitamin D supplementations are also given to slow bone density losses and decreases the risk of osteoporotic fracture in men and women.

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Vitamin E

Vitamin E is a collective name for all stereoisomers of tocopherols and tocotrienols.The most biologically active form is α-tocopherol, butβ-, γ-, δ-tocopherols,4 tocotrienols, and several stereoisomers may also have important biologicalactivity.  Vitamin E acts as achain-breaking antioxidant and is an efficient free radical scavenger, to protect low-density lipoproteins (LDLs) and polyunsaturated fats in membranesfrom oxidation. A network of other antioxidants (e.g., vitamin C, glutathione)and enzymes maintain vitamin E in its reduced state. 

Absorption and Metabolism

After absorption, vitamin E is taken up from chylomicrons by the liver, and a hepatic α-tocopherol transport protein mediates intracellular vitamin E transport and incorporation into very low-density lipoprotein (VLDL). The transportprotein has particular affinity for α-tocopherol; thus this natural isomer has the most biologicactivity.

Requirement

VitaminE is widely distributed in the food supply and is particularly high insunflower oil, safflower oil, and wheat germ oil; γ tocotrienols are notably present in soybean and corn oils.Vitamin E is also found in meats, nuts, and cereal grains, and small amountsare present in fruits and vegetables. The RDA for vitamin E is 15 mg/d (34.9 μmol or22.5 IU) for all adults. Diets high in polyunsaturatedfats may necessitate a slightly higher requirement for vitamin E.

Functions of vitamin E

1) It acts as a lipid-soluble antioxidant in cell membranes, and is important inmaintaining the fluidity of cell membranes.

Antioxidant role of vitamin E

Reactive oxygen species (ROS) are molecular oxygen metabolites that arehighly reactive with lipids, proteins, and DNA, causing oxidative damage tothese cellular macromolecules. This damage, termed oxidative stress, accumulates over time and is thought tocontribute to both disease pathology and the aging process. Cellular mechanismsthat exist to counteract ROS include stabilization by enzymes such as superoxidedismutase and Catalase, and direct scavenging by antioxidant molecules such asglutathione (GSH) and a major extracellular antioxidant in plasma; vitamin E, a major lipidsoluble antioxidant; and ascorbate, a critical intracellular and extracellularantioxidant.

The main function of vitamin E is as a chain-breaking, free-radical trappingantioxidant in cell membranes and plasma lipoproteins.

By reacting with the lipid peroxide radicals formed byperoxidation of polyunsaturated fatty acids, it gets converted to tocopheroxyl radical.The resultant radical (Oxidized form) is relatively unreactive, and ultimatelyforms nonradical compounds. Commonly, the tocopheroxyl radical is reduced backto tocopherol by reaction with vitamin C from plasma. (See Figure)

Ascorbate (Vitamin C) is essential formaintaining vitamin E in its reduced, active form. Ascorbate is oxidized todehydroascorbate in plasma and that is recycled back to ascorbate by GSH aswell as by several enzyme systems in erythrocytes, neutrophils, endothelial cellsand hepatocytes (See figure). 

GSH itself gets oxidized during this process andis converted back to its reduced form by Glutathione reductase utilizingNADPHas the reductant.  GSH is also required bySelenium containing Glutathione Peroxidase enzyme for decomposing H2O2.

A synergism is observed between seleniumand vitamin E .The synergism is related to theprocessof antioxidation, wherein tocopherols tend to preventoxidativedamage to polyunsaturated fats in cell membranes,whereas selenium,as part of seleno-enzyme glutathione peroxidase,catalyzes  thedestruction of lipid hydro peroxides. This explainshow these twonutrients play separate but interrelated rolesin the cellular defensesystem against oxidative damage. Vitamin E deficiency results in failure to scavengefree radicals and as a consequence there is membrane disruption especially ofred blood cells.(See the details below)

As an antioxidant, vitamin E plays a protective role inmany organs and systems. Vitamin E is necessary for maintaining a healthyimmune system, and it protects the thymus and circulating white blood cellsfrom oxidative damage. Also, it may work synergistically with vitamin C inenhancing immune function. Recent research evidence indicates that the combineduse of high doses of vitamin C and vitamin E helps prevent Alzheimer’s disease.In eyes, vitamin E is needed for the development of the retina and protectsagainst cataracts and macular degeneration. 

Figure- showing the anti oxidant role of vitamin E, A synergism is observed between Vitamin E,C and G-SH dependent Glutathione peroxidase.

2) Other functions of vitamin E- It also has a (relatively poorly defined) role in cell signaling. Besides that, Vitamin Einhibits prostaglandin synthesis and theactivities of protein kinase C and Phospholipase A₂.

3) In highconcentration, the tocopheroxyl free radical can penetrate further into cellsand, potentially, propagate a chain reaction. Therefore, vitamin E may, likeother antioxidants, also have pro-oxidantactions, especially at high concentrations. This explains the bleedingobserved in vitamin E toxicity.

Vitamin E Deficiency

Dietary vitamin E deficiency is common in developingcountries; deficiency among adults in developed countries is uncommon and is usuallydue to fat malabsorption. The mainsymptoms are hemolytic anemia and neurologic deficits.

Etiology

Absorption of vitamin E depends on normalpancreatic biliary function, biliary secretion, micelle formation, andpenetration across intestinal membranes. Interference with any of theseprocesses could result in a deficiency state.

Indeveloping countries, the most common cause is inadequate intake of vitamin E.In developed countries, the most common causes are disorders that cause fat malabsorption, including Abetalipoproteinemia(genetic absence of Apo lipoprotein B), chronic cholestatic hepatobiliarydisease, pancreatitis, short bowel syndrome, and cystic fibrosis.

Vitamin E deficiency is seen in only severeand prolonged malabsorptive diseases, such as celiac disease, or aftersmall-intestinal resection. Children with cystic fibrosis or prolongedcholestasis may develop vitamin E deficiency characterized by areflexia andhemolytic anemia.

Children with Abetalipoproteinemia cannot absorb or transportvitamin E and become deficient quite rapidly.(Apo B48 is required for chylomicron formation and that is needed for transportation of vitamin E from gut to liver)

Isolated vitamin E deficiency syndrome - Developing in the absence of fat malabsorption, this syndrome iscaused by an autosomal-recessive genetic disorder. Neurologic findings developwithin the first decade of life. It is due to a defect in the α-tocopheroltransport protein.

Clinical manifestations

The main symptoms are-

Mild hemolytic anemia and nonspecific neurological deficits

Biochemical basis of hemolytic anemia- Vitamin E deficiency results in oxidative damage to thered cell membrane, with the resultant altered permeability and osmolysis.(Seethe flowchart below)

Flow chart- showing the biochemical basis of hemolytic anemia observedin vitamin E deficiency

Bochemical basis of Ataxia and neurological symptoms- Vitamin E deficiency causes axonal degeneration of thelarge myelinated axons and results in posterior column and spinocerebellarsymptoms. Peripheral neuropathy is initially characterized by areflexia, withprogression to an ataxic gait, and by decreased vibration and positionsensations.

In adults with malabsorption, vitamin Edeficiency very rarely causes spinocerebellar ataxia because adults have largevitamin E stores in adipose tissue.

Diagnosis

Low α-tocopherollevel or low ratio of plasma α-tocopherol to plasma lipids

Measuring the plasma α-tocopherollevel -is the most direct method of diagnosis. In adults, vitamin E deficiencyis suggested if the α-tocopherol level is < 5 μg/mL(< 11.6 µmol/L).

Because abnormal plasma lipid levels can affect vitamin E status, a low ratio of plasma α-tocopherol toplasma lipids (< 0.8 mg/g total lipid) is the most  accurate indicator in adults with hyperlipidemia.

In children and adults with Abetalipoproteinemia, plasma α-tocopherollevels are usually undetectable.

Prevention

Although premature neonates may require supplementation, human milk and commercialformulas have enough vitamin E for full-term neonates.

Treatment

Supplemental α-tocopherol

If malabsorption causes clinically evident deficiency, α-tocopherol15 to 25 mg/kg orally once/day should be given. However, larger doses given byinjection are required to treat neuropathy during its early stages or toovercome the defect of absorption and transport in Abetalipoproteinemia.

Vitamin E Toxicity

Many adults take relatively large amounts of vitamin E (α-tocopherol 400to 800 mg/day) for months to years without any apparent harm. Occasionally,muscle weakness, fatigue, nausea, and diarrhea occur. The most significant riskis bleeding. However, bleeding is uncommon unless the dose is > 1000 mg/day or the patient takes oral coumarin or warfarin.

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