Water Soluble Vitamins Flashcards
1
Q
Non-B complex
A
Ascorbic acid (Vitamin C)
2
Q
B complex vitamins: Energy releasing vitamins?
A
Thiamine (Vitamin B1) Riboflavin (Vitamin B2) Niacin (Vitamin B3) Biotin Pantothenic acid
3
Q
B complex vitamins: Hematopoietic vitamins?
A
Folic acid
Vitamin B12
4
Q
B complex vitamins (Other)
A
Pyridoxine (Vitamin B6)
Pyridoxal
Pyridoxamine
5
Q
What are vitamins?
A
Organic, essential molecules that are required in tiny amounts to maintain normal growth, development, and metabolism. We cannot synthesize them or can’t synthesize them in adequate amounts.
6
Q
Vitamins that affect bone health?
A
A, D, K, C
7
Q
Vitamins that affect energy metabolism?
A
Thiamin Riboflavin Niacin Pantothenic acid Biotin Vitamin B12
8
Q
Vitamins that affect blood formation and clotting?
A
Vitamin B6
Vitamin B12
Folate
Vitamin K
9
Q
Vitamins that affect protein and amino acid metabolism?
A
Vitamin B6 Folate Vitamin B12 Vitamin C Choline (NOT A TRUE VITAMIN) Riboflavin (indirect)
10
Q
Vitamins that affect antioxidant defenses?
A
Vitamin E
Vitamin C
Carotenoids
Riboflavin (indirect)
11
Q
Vitamins that affect gene expression?
A
Vitamin A
Vitamin D
12
Q
How do vitamins differ from carbohydrates, fat, and proteins?
A
Vitamins: Organic No calories MICROnutrients Foods contain very small amounts (mg or ug)
Carbs, fats, proteins: Organic Provides calories MACROnutrients Foods contain relatively large amounts (grams)
13
Q
Factors influencing bioavailability
A
- Efficiency of digestion (ex. decreased acid production in stomach, vitamin B12 bioavailability decreases).
- Time of transit (ex. diarrhea)
- Method of food preparation - raw, cooked, or processed (ex. boiling spinach, liquid).
- Previous nutrient intake and nutrition status
- Source of nutrient (synthetic, fortified, or naturally occurring)
- Other foods consumed at same time
14
Q
What is fortification?
A
When vitamins and minerals are added to foods to increase their nutritional value.
ex. Folic acid often added to breakfast cereals, flour, and certain spreads.
15
Q
Digesting and Absorbing Water-Soluble Vitamins
A
- Vitamins are hydrolyzed in the stomach from the protein complexes found in food.
- Most of the water-soluble vitamins absorbed in the UPPER small intestine with the exception of Vitamin B12 (absorbed in ILEUM).
- Water-soluble vitamins are absorbed DIRECTLY into the portal vein and transported to the liver, where they are either stored (B12) or sent out into circulation.
- Excess water-soluble vitamins are excreted through the kidneys in the urine.
**Exceptions: Vitamin B12 and Vitamin B6 (Pyridoxine) - stored to a greater extent, takes longer to develop a deficiency.
16
Q
Do we store water-soluble vitamins?
A
No (not most! VB12, VB6 exceptions) so we do not encounter toxicities unless they are consumed as mega dose supplements.
17
Q
What are cofactors?
A
Accessory molecules that are important for protein or enzyme function. They can be inorganic molecules (ex. minerals) or organic (ex. coenzymes). These coenzymes may be co-substrates for specific enzymes and are essential for the catalysis of metabolic reactions and they are recycled.
18
Q
Prosthetic group examples?
A
Heme, Vitamin B12, FAD (active form of riboflavin)
19
Q
What are the sources of Vitamin B1 (Thiamin)?
A
Whole grain products, meat, sunflower seeds, total cereal (fortification).
20
Q
How is Vitamin B1 (Thiamin) metabolized?
A
Must be phosphorylated to THIAMIN PYROPHOSPHATE (TPP)(ACTIVE FORM).
21
Q
Once absorbed, where is thiamine found?
A
Tissues that have high metabolic rate such as skeletal muscles, heart, and brain.
22
Q
What can reduce absorption of thiamine?
A
Alcohol consumption; individuals with folate deficiency
23
Q
What are the functions of Thiamine (B1)?
A
Helps body’s cells convert carbohydrates into energy.
Essential for functioning of heart, muscles, and nervous system.
Enzymes that use thiamine as a coenzyme:
1. PDH: Pyruvate dehydrogenase
2. Alpha-ketoglutarate dehydrogenase
3. BCK-DH: Branched-chain alpha-ketoacid dehydrogenase-Amino acid metabolism, LIV
4. Transketolase (HMP pathway)
Non-coenzyme roles of thiamine and its phosphorylated derivatives.
24
Q
What enzymes use thiamine as a coenzyme?
A
- Pyruvate dehydrogenase
- Alpha-ketoglutarate dehydrogenase
- BCK-DH: Branched-chain alpha-ketoacid dehydrogenase-Amino acid metabolism, LIV
- Transketolase (HMP pathway)
25
Thiamine deficiency is rare in the US; who is prone?
Malnourished, homeless patients
Alcoholics (WERNICKE KORSAKOFF SYNDROME)
Patients on weight-loss diets (ex. Atkins, Ornish, LEARN plans). **Should be advised to take multivitamin**
26
What are the early symptoms of thiamine deficiency?
```
Poor appetite
Irritability
Apathy
Confusion
Weight loss
```
27
Consequences of prolonged thiamine deficiency?
Beriberi, rare in U.S.
28
Dry beriberi: cause and symptoms
Thiamine deficiency
Neurologic disorders, Muscle wasting. Pain, numbness, tingling of the lower extremities. In alcoholics, symptoms can progress and give rise to WERNICKE-KORSAKOFF syndrome with encephalopathy and psychosis.
29
Wet beriberi: cause and symptoms
Thiamine deficiency
| Edema due to cardiovascular problems
30
Thiamine - toxicities?
No.
31
What are the sources of Vitamin B2 (Riboflavin)?
```
Milk and milk products
Whole grains, enriched or fortified grain products.
Beef LIVER
Mushrooms
Spinach
```
32
Active forms of B2?
| Form and Absorption of Vitamin B2 (Riboflavin) - What does it bind to?
Circulate in the body bound to ALBUMIN or other serum proteins.
Once in cell, riboflavin is converted to flavin mono nucleotide (FMN) and flavin adenine dinucleotide (FAD).
33
Functions of Riboflavin? (Vitamin B2)?
FAD and FADH2 are active forms and are prosthetic groups for many enzymes.
Involved in oxidation and reduction reactions (OxPhos, Glutathione Reductase- for removal of reactive oxygen species (ROS))
34
Deficiency and toxicity of Riboflavin (Vitamin B2)
Inflammation of membranes
- sore throat, cheilosis, glossitis, stomatitis, seborrheic dermatitis
Bloodshot eyes, sensitive to bright light
Toxicity - no adverse effects
35
Vitamin B3
Niacin
36
Vitamin B2
Riboflavin
37
Vitamin B1
Thiamine
38
Sources of Niacin (Vitamin B3)?
Protein-rich foods (meat, fish, poultry, peanut butter)
Mushrooms
Asparagus
Fortified foods (cereal, chicken)
39
Active form of Niacin
NAD and NADP
40
Niacin can be made from...
nicotinic acid, nicotinamide or from tryptophan.
41
What is the major form of niacin?
Nicotinamide
42
Niacin Function
NAD and NADP together are used in hundreds of reactions which involve both production and breakdown of glucose, fats, amino acids, and nucleotides.
43
Niacin Deficiency: Who is prone? Symptoms?
Alcoholics, corn-based diets
PELLAGRA (rough skin)(4D's!!!!)
- Diarrhea, dermatitis, dementia, death
(Casal's necklace).
44
Initial signs of Niacin deficiency?
Fatigue, loss of appetite, weakness, anxiety, irritability, depression, GI disturbance
45
Niacin toxicity
From supplementation
Niacin FLUSH and itching - seen in patients taking large amounts of nicotinic acid for lowering LDL
- can be treated with low dose aspirin or ibuprofen (Advil)
46
Vitamin B6
Pyridoxine
47
Sources of Pyridoxine (Vitamin B6)?
```
Protein-rich foods
Starchy vegetables
Non-citrus fruits
Potatoes, oatmeal, bananas, pistachios, pinto beans
BANANA 2 Ps!!!
```
48
What are the forms of Vitamin B6?
Pyridoxal (animal), pyridoxine, pyridoxamine (plants)
49
Absorption of Vitamin B6?
Vitamin 6 (3 forms - pyridoxal, pyridoxine, pyridoxamine) are all converted to pyridoxal phosphate (PLP) - important for A.A. metabolism.
50
Where is Vitamin B6 stored?
Exclusively in muscle tissue
51
Vitamin B6 (Pyridoxine) Function
Amino acid metabolism
Urea metabolism
Conversion of tryptophan to niacin or serotonin, dopamine, norepi, histamine
Synthesis of heme **IN COMMITTED STEP AS A COENZYME FOR ALA SYNTHASE**
52
Pyridoxine (Vitamin B6) Deficiency: who's prone?
```
Rare.
Newborn infants fed formulas low in B6
Women taking oral contraceptives
Alcoholics
*Consequence of drug interactions!*
- Tuberculosis (Isoniazid)
- Rheumatoid arthritis (Penicillamine)
```
53
What is Isoniazid?
Used for treatment of tuberculosis, but also binds Vitamin B6 inducing deficiency.
54
What is Penicilliamine?
Used for treatment of rheumatoid arthritis; also depletes pyridoxine pools leading to deficiency.
55
Pyridoxine (VitB6) deficiency presentation?
Cheliosis, glossitis, pellagra-like dermatitis, depression, confusion
*Pyridoxine deficiency may lead to niacin deficiency*
56
Pharmacological use of Pyridoxine
Used to treat carpal tunnel syndrome, PMS, asthma, depression, during pregnancy to control nausea, diabetic neuropathy. *because of side effects, NOT recommended for PMS*
57
Pyridoxine Toxicity
Irreversible nerve damage
- severe sensory nerve damage
- walking difficulties
- numbness of hands and feet
58
Vitamin B9
Folate
59
Sources of Vitamin B9 (Folate)?
Dark leafy vegetables (spinach, broccoli, legumes, citrus fruits)
LIVER
Fortified foods (man-made analog, folic acid)
Orange juice, lentils
60
Forms of Folate
Tetrahydrofolate
| Methyltetrahydrofolate
61
Forms of folate in nature
3-5 glutamates at end.
In intestine (methyltetrahydrofolate) removed until we have a single glutamate.
In epithelial cells folate becomes methylated.
62
Transformation of Methylfolates into other forms
Vitamin B12 comes to activate folate in cells. It picks up the methyl group. This allows B12 to be activated also.
63
Function of Folate
Synthesis of DNA, RNA, some amino acids
- Critical for rapidly dividing cells
Regenerate methionine from homocysteine
64
Folate Deficiency will lead to...
MACROCYTIC ANEMIA - weakness, fatigue, headache, palpitations, shortness of breath
65
Folate Deficiency may be caused by...
```
Suboptimal intake
Increased utilization (pregnancy)
Inadequate absorption (Celical disease, Crohn's)
Antifolate therapy (Methotrexate)
Alcoholics
Elderly with poor diet
Antacids
*Folate supplementation can reverse the anemia, but not neurologic damage caused by B12 deficiency)
```
66
Neural Tube, Folate supplementation
Recommend moms taking folic acid at least a month before pregnancy and continue supplementation during pregnancy to lower chance of spina bifida, anencephaly.
67
Folate and Heart Disease
High levels of homocysteine (due to folate deficiency) may be a marker for increased risk of developing heart disease. Decrease the risk of strokes in smokers.
68
Folate Toxicity
Excessive consumption may mask B12 deficiency, allowing neurologic problems to progress in spite of anemia being resolved.
69
Vitamin B12
Cobalamin
70
Sources of Cobalamin
Foods of animal origin (made by bacteria) Vegans will be deficient!
Fortified or fermented foods (ex. soy milk)
71
Active forms of Cobalamin
Active forms:
1. Methylcobalamin
2. Deoxyadenosylcobalamin
72
Digestion and Absorption of Cobalamin
1. Salivary glands produce R protein.
2. In stomach:
- vitamin B12 is released from protein and binds R protein.
- IF is released from parietal cells.
- R protein bound B12 and IF move to duodenum
3. Pancreatic enzymes cleave R protein, VB12 binds to IF from here to ileum.
4. At ileum, IF receptors allow internalization of B12. In ill epithelial cells, B12 is released from IF and released to hepatic circulation and transported bound to TRANSCOBALAMIN II to be delivered to LIVER.
73
Functions of Cobalamin
Regeneration of methionine, synthesis of DNA, synthesis of RNA
Metabolism of odd-numbered fatty acids and several amino acids.
Helps to maintain nerve cells.
*B12 and folate depend on each other for activation*
74
Reasons for Cobalamin Deficiency
Decreased intake (vegan, malnutrition)
Malabsorption (decreased IF: autoimmune disease, elderly)
- Decreased gastric acid (proton pump inhibitors)
- Removal of terminal ileum (Bariatric surgery, Crohn's, Cancer).
Pernicious anemia (due to destruction of parietal cells, which make IF, autoimmune).
75
Symptoms of Cobalamin Deficiency
Megaloblastic anemia
Nerve damage (tingling hands and feet)
Painful swollen tongue
76
Vitamin B7
Biotin
77
Functions of Biotin
Co-enzyme that adds CO2 to compounds
Required for metabolism of carbohydrates, fats and proteins
ABC Carboxylases (ATP, Biotin, CO2)
78
Biotin Deficiency
```
Rare
Biotinidase enzyme deficiency
Excessive consumption (>12) of raw eggs (avidin)
```
79
Biotinidase deficiency
Body is unable to recycle biotin.
Genetic disorder, autosomal recessive.
Symptoms:
Muscle weakness, seizures, eczema, alopecia, developmental delays, lactic acidosis
80
Vitamin B5
Pantothenic acid
81
Sources of Vitamin B5
Meat, milk, many vegetables
82
Form of B5
Part of Coenzyme A, Acyl carrier
83
Functions of B5
Synthesis of fatty acids, triacylglycerol, cholesterol, and Ach.
Synthesis of cell membranes.
Deficiencies are RARE.
84
Interactions among the B vitamins
Folate and B12
FMN (riboflavin, B2) is important for conversion of Vitamin B6 (pyridoxine) to pyridoxal phosphate (PLP)
FMN, PLP (as well as iron) are required for conversion of Trp to niacin (B3)
85
Vitamin C
Ascorbic Acid
86
Scurvy
Muscle weakness, joint pain, impaired wound healing, loose tooth, bleeding and swollen gums, bruised skin and fatigue.
87
Sources of Vitamin C
Veggies and fruits
88
Functions of Vitamin C
Formation of collagen (bones and blood vessels, anchoring teeth, tissue repair, wound healing)
Water soluble antioxidant
Synthesis of neurotransmitters
Synthesis of carnation which is important for fatty acid degradation
Increases the bioavailability of iron from foods by enhancing intestinal absorption of non-heme iron
89
What makes Vitamin C a great antioxidant?
Readily loses its electrons to free radicals and to ROS, thereby protecting proteins, nucleic acids, carbs, and lipid damage from oxidation.
Vitamin C is REVERSIBLE - can be reduced to its active form.
90
Vitamin C is a cosubstrate for which 2 enzymes? What do these enzymes do?
1. Prolyl hydroxylase (catalyzes selective modification of proline to hydroxyproline)
2. Lysyl hydroxylase (lysine to hydroxylysine)
**IMPORTANT FOR COLLAGEN SYNTHESIS**
91
Vitamin C Deficiency: Who's prone?
Urban or poor older adults, severe burns, fractures, alcoholics, smokers (depletes tissue levels)
92
Scorbutic gums, Pinpoint hemorrhages
Symmetrical appearance of lesions without infection in gums
| Vitamin deficiency due to internal bleeding
93
Vitamin C Toxicity
Vitamin C is metabolized to oxalic acid
| Patients with history of oxalate kidney stones should avoid high doses
94
Vitamin C as medicine?
Doesn't prevent cold, but can help reduce severity.
| Reduces oxidation of LDL cholesterol.
95
Describe basic structure of folate
Basic structure: ring structure known as pteridine, followed by para-aminobenzoic acid (PABA) as a bridge molecule which in turn is connected to glutamate.
Carry and transfer various forms of one carbon units during biosynthetic reactions.
96
What is the synthetic form of cobalamin?
Cyanocobalamin
