Unit 9: Micronutrients – Water-soluble Vitamins Flashcards
Generalizations of B vitamins
1 • Function as __________ for
– Energy metabolism or
– Cell division
2 • All B vitamins are absorbed by the small intestine,
transported via capillary to the body
– Except _____ – requires some binding proteins for ACTIVE absorption
– Alcohol or barbiturates block absorption of many B vitamins. Alcoholics are prone to vitamin B deficiency
3 • Converted to coenzyme forms in the intestinal mucosa and/or the _______
4 • Usually stored in muscle and internal organs
(liver, kidney, heart)
5 • Except B12, B vitamins and their metabolites are water soluble and are excreted in urine
– Enhanced by diuretics
– B12 is excreted in BILE; water-soluble metabolite in urine
coenzymes
B12
liver
Vitamin B1 (Thiamin, Anti-beriberi factor)
1–• Required by Alcohol dehydrogenase
2–Biosynthesis of nucleic acids and _______
3–Nerve integrity and function
4.–Muscle integrity and function
lipids
Vitamin B1 : Function
1—Pyruvate dehydrogenase
complex = Conversion of pyruvate to
______
2–α-ketoglutarate dehydrogenase = Conversion of succinyl-CoA in Kreb’s cycle
acetyl-CoA
Thiamin Deficiency
1–Wet beriberi = ______ of legs, face, trunk, and serous
cavities
2–Dry beriberi = Worsening of early-stage polyneuritis,
Difficulty walking, ______________ syndrome: possible
Encephalopathy
Vitamin B1 Excess = Reported signs are nervousness,
tachycardia, shortness of breath and perspiration
Edema
Wernicke-Korsakoff
How Alcohol Affects Absorption
1 • inhibits the breakdown of nutrients into usable molecules by decreasing secretion of digestive enzymes from the ________
2 • impairs nutrient absorption by DAMAGING the cells lining the ______&_________ and DISABLING transport of some nutrients into the blood
3 • Even if nutrients are digested and absorbed, alcohol can prevent them from being fully utilized by ALTERING their transport, storage, and excretion.
– Decreased liver stores of vitamins such as vitamin A, and increased excretion of nutrients such as fat, indicate impaired utilization of nutrients by alcoholics
4 • In addition, nutritional deficiencies themselves may lead to further absorption problems.
– Ex., folate deficiency alters the cells lining the small intestine, which in turn impairs absorption of water and nutrients including glucose, sodium, and additional folate
pancreas
stomach and intestines
Vitamin B2 (Riboflavin): Function
Biologically Active Forms are FMN and FAD
1–____: the main form of riboflavin found in cells and tissues.
2–____–(Carbon skeleton used for gluconeogenesis & energy)
3–Antioxidation of glutathione
– Glutathione reductase is a flavoprotein
4—Riboflavin Deficiency = Increased energy needs
5–Excess =Excessive supplementation can lead to orange colored urine
–
FMN
FAD
Vitamin B3: Niacin, niacinamide, anti-pellagra factor
1–Required by Alcohol dehydrogenase
2–Function =
• Antioxidation: Regeneration of glutathione (NADPH)
• Nerve integrity and function
• Skin integrity and function
3–Daily doses of 250-1000 mg niacin with a HMG-CoA inhibitor prevents ________ _________
4–We are able to synthesize niacin
– From ___________
– Requires Vitamin B_ as a coenzyme
5–Niacin (aka nicotinic acid, Vit B3)– 1 mg niacin = 60 mg tryptophan
primary stenosis
tryptophan
6
Symptoms—Vitamin B3: Niacin, niacinamide, anti-pellagra factor
– Pellagra (Italian- ‘rough skin’): “3Ds”
1 • Dermatitis: Casal’s Necklace and lesions; inflamed lips/tongue
2 • Diarrhea
3 • Dementia
***• Death = 4th D
Vitamin B3 (Niacin): Excess 1--– Histamine release (\_\_\_\_\_\_, worse allergies, aggressive peptic ulcers)
flushing
Vitamin B5/ Pantothenic Acid: Function
- ENERGY production, CoA for
– Pyruvate to acetyl-CoA (pre-Krebs)
– α-ketoglutarate to succinyl-CoA (Krebs)
– β-oxidation of fatty acids (acyl-CoA) - Biosynthesis of ______
– Acetyl-CoA, acyl-CoA and acyl-carrier protein (ACP) of
fatty acid synthase - Biosynthesis of acetylcholine, porphyrin
- Skin integrity
- Vitamin B5/ Pantothenic Acid: Deficiency
– Dermatitis
– Hair loss
– Fatigue
– Muscle cramps
lipids
Vitamin B6 (Pyridoxine) : Function
1–Energy production:
– Pyridoxal phosphate as coenzyme for ________ of
amino acids to form ketoacids for energy
– Prosthetic group in glycogen phosphorylase
2–As a coenzyme for
– Biosynthesis of amino acids by ____________
– Niacin from tryptophan
– Heme from succinyl-CoA
– Glycine and sphingosine from serine
3–Decarboxylation of glutamic acid to form γ-
aminobutyric acid (_____)
deamination
transamination
GABA
Vitamin B6 (Pyridoxine) : Deficiency Symptoms:
– Weakness
– Convulsions
– Dermatitis
– ___________ microcytic anemia
– Oxalate kidney stones
– If tryptophan –X = niacin, then pellagra
Excess = Neuropathy = Walking difficulty and sensory disorders
Iron-loading
Vitamin B7 (Biotin): Function (Intestinal flora!)
1–Energy
2–Gluconeogenesis
3–Biosynthesis of fatty acids
4–Biosynthesis of nucleic acids
5–Cell growth by increasing intracellular cGMP
6–Skin integrity
7– ________ formation
8–deficiencies of biotin = – Use of ____________ and sulfonamides & Dandruff / cradle cap
Antibody
antibiotics
Vitamin B9: Folate, Folacin, Hemopoietic Factor
Function
1 • ___ _________– growth, repair and hematopoiesis (dUMP to TMP to DNA)
2 • Biosynthesis of purine and pyrimidine nucleotides
3 • Histidine metabolism
4–(H4) Folate: key biologically active form of folate
5–Transport – By folacin transport protein of plasma in blood • WHY? Because water solubility is _____.
Folate Deficiency = Impaired biosynthesis of _____ &_____
Vitamin B9 (Folate): Excess = – Masks _____ deficiency, results in neurological disorders
Cell division
low
DNA and RNA
B12
Vitamin B12 : Cobalamin, Anti-pernicious Anemia factor
- Contains ______; only vitamin that requires a mineral
- Not naturally found in plant foods
- Function =
A. Cell division and hematopoiesis
– Methylcobalamin is req’d for conversion of methyl-H4
-folate»_space; H4-folate
– Without B12, methyl-H4-folate cannot be___________ = “Methyl Folate Trap”
– Both B12 and folate are required for ____ _______
B. Energy or gluconeogenesis
– Utilization of propionyl-CoA
C. Nerve integrity and function
cobalt
recycled
cell division
Vitamin B12 : Cobalamin
Absorption – Normally an _____ process B12 + Intrinsic Factor + Ca2+
1—IF is a glycoprotein produced by the parietal cells of the stomach
2—Complex absorbed in the ilium
3–Impaired absorption = __________ ________ (megaloblastic, macrocytic) due to
• Lack of IF, defective IF
active
Pernicious anemia
