L12: Vitamins, Minerals and Alcohol Metabolism Flashcards
Water Soluable Vitamains?
B Complex (8)
Vitamin C
Fat Soluable Vitamins
A
D
E
K
Vitamins that Function as Co-Enzymes/ Co-Factors?
Vit A (Rhodopsin-Rod Cells)
Vit B Complex (8)
Vit K (Blood Clotting)
Vitamins that Function as Antioxidants?
Vit A
Vit C
Vit E
Vitamins that have Hormonal Functions?
Vit A (Epithelial Maintenance)
Vit D (Ca++ metabolism)
Functions of B-Complex Vitamins?
- Energy metabolism – generation of ATP from glucose and fats
- Amino acid metabolism
- Nucleotide synthesis
Enzymes that require Vitamin B1
Resulting Deficiency?
These Enzymes require Thiamin (B1)
- Pyruvate Dehydrogenase
- a-Ketogluterate Dehydrogenase
Deficiency results in Beriberi: Muscle wasting disease
What causes Beriberi?
B1 Thiamin deficiency
What is Vitamin B2 (Riboflavin) a precursor for?
NAD
What is Vitamin B3 a precursor for?
Resulting Deficiency?
B3 (Niacin) is a Pre-cursor of NAD
Pellagra: Sour Skin Dermatitis on hands and shoulder (Casal’s Collar)
What causes Pellagra?
B3 (Niacin) deficiency
Constituent of Co-A (Part of Acyetly Co-A)?
B5 (Pantothenic acid)
Co-enzyme in carboxylation/FA synthesis?
B7 (Biotin)
Role of Vitamin B9?
Resulting Deficiency?
Folic acid- B9 is essential for Neural tube formation
Spina Bifida: Neural tube deficiency
Co-enzyme key in Erythropoiesis?
B12 (Cobalamin)
What causes Spina Bifida?
Deficiency of Vitamin B9 (Folic Acid) causes impaired DNA replication in dividing cells => neural tube defects
What causes Pernicious Anemia?
Low red blood cell production resulting from lack/loss of intrinsic factor needed for the absorption of vitamin B12-Cobalmin. Intrinsic Factor deficiency caused by autoimmune disease targeting parietal cells of the stomach/ intrinsic factor)
Vitamin that is an essential cofactor in Amino Acid Metabolism?
Consequences of Deficiency?
Pyridoxal (B6) Phosphate is responsible for:
- All transamination reactions
- Some AA decarboxylation and deamination reactions
- Synthesis of neurotransmitters (GABA and serotonin)
- Heme biosynthesis
Deficiency rare - most common in alcoholics
- Anemia
- Peripheral neuropathy/ Seizures
Vitamin deficiency responsible for Anemia, Peripheral neuropathy and Seizures?
B6 Pyridoxal
Causes of B-Complex Deficiencies?
B Vit Deficiencies uncommon except in severe malnutrition and alcoholism
Are B-vitamins always good for you??
NOT protective against lung cancer, may even be harmful for men
Roles of Vitamin C?
Resulting Deficiency?
General antioxidant: scavenges free radicals preventing lipid peroxidation and DNA damage
Specific antioxidant: Many Fe and Cu-containing enzymes are dependent on ascorbic acid to maintain metals in the reduced state required for enzyme activity
- Prolyl and lysyl hydroxylases: Collagen synthesis
- Carnitine synthesis: b-oxidation of Fatty acids
- Bile acid synthesis
Deficiency results in Scurvy
How does Vitamin D Upregulate Bone Mineralization
Vitamin D undergoes Hydroxylationin liver then the Kidneys becoming Calcitriol => Calcitriol binds receptors in the intestinal mucosa which increases calcium channel expression in lumen of the intestine => Upregulates Bone Mineralization
Manifestations of Vitamin D Deficiency in Children/Adults?
Children – Rickets: inadequate bone calcification; soft cartilaginous bones
Adults – Osteomalacia: Brittle bones that break easily
Intermediate associated with adverse effects of alcohol?
Acetaldehyde
Metabolism of Normal Levels of Alcohol?
Alcohol broken down in cytosol of hepatocytes by Alcohol Dehydrogenase (ADH) to acetaldehyde =>mitochondria for conversion to Acetic Acid by Aldehyde Dehydrogenase (ALDH)
Metabolism of Chronic, High Levels of Alcohol?
Tolerance developed: in response to high consumption, additional breakdown of alcohol to acetaldehyde by Alcohol Dehydrogenase (ADH) in microsomal compartment of hepatocytes =>mitochondria for conversion to Acetic Acid by Aldehyde Dehydrogenase (ALDH)
What cofactors/Enzymes are essential for alcohol Metabolism?
Alcohol Dehydrogenase (ADH)
Aldehyde Dehydrogenase (ALDH)
NAD+
Why is Alcohol considered to be empty calories?
NAD+ diverted from normal metabolism => Excess production of NADH in the liver (NAD+ Key in Kreb’s Cycle and Fatty Acid Oxidation) leading to:
- Decreased gluconeogenesis
- Decreased fatty acid breakdown => accumulation of fat in liver
Vitamin Deficiencies commonly seen with chronic alcoholism?
Thiamine (B3), Pyridoxal (B6), Folate (B9)
Vitamin A
What does a combination of Alcohol Toxicity and Thiamine (B1)
deficiency lead to? Acute/Chronic manifestations?
Wernicke-Korsakoff Syndrome
- Acute: delirium, ataxia, paralysis of eye muscles
-
Chronic: Korsakoff psychosis = severely debilitating short-term
memory loss. Preventable by thiamine injections.
