Vitamins Flashcards
(24 cards)
Vitamin B1
Thiamine Coenzyme: Thiamine Pyrophosphate (TPP) -Pyruvate DH -a-ketoglutarate DH - branch chain ketoacid DH (MSUD) - Transketolase
Vitamin B1 deficiency
Caused by alcoholism
Wernicke’s (ataxia, nystagmus, opthalmoplegia)
Korsakoff’s (psychosis, confabulation)
Dry beriberi (muscle wasting, partial paralysis)
Wet beriberi (cardiac failure, peripheral edema)
Vitamin B2
Riboflavin
Coenzyme: FAD/FMN
Vitamin B2 deficiency
Caused by poor dietary intake or malabsorption syndromes Corneal neovascularization Cheilosis/ Stomatitis Magenta colored tongue **Think mouth
Vitamin B3
Niacin
Coenzyme: NAD/NADP
Synthesized from Trp
Vit B3 Deficiency
Deficiency from Hartnup disease (Trp deficiency leads to niacin deficiency)
Malnutrition leads to Pellagra (4 D’s)
Pellagra
Diarrhea
Dementia
Dermatitis
Death
Vitamin B5
Pantothenic Acid Coenzyme A -Pyruvate —> TCA -a-ketoglutarate —> succinyl CoA - FA metabolism - Cholesterol synthesis Required for acetylation and acylation
Vit B5 Deficiency
Caused by extreme starvation
Dermatitis, numbness, paresthesia, muscle cramps, enteritis, alopecia, adrenal insufficiency, hypoglycemia
Vitamin B6
Pyridoxine Converted to pyridoxal phosphate in body Aminotransferase rxns (ALT & AST) Delta-aminolevulinate synthase (rate limiting step in heme synthesis)
Vitamin B6 Deficiency
Deficiency from isoniazid therapy
Sideroblastic anemia
Cheilosis/ stomatitis
Intertrigo (skin inflammation in warm, moist areas (i.e.groin))
Convulsions
Vitamin B7
Biotin Cofactor for carboxylation enzymes -Pyruvate carboxylase - Acetyl CoA Carboxylase - Propionyl CoA carboxylase
Vitamin B7 Deficiency
Deficiency from excessive consumption of raw eggs
Alopecia
Rashes, seborrheic dermatitis (scaly patches and dead skin mainly on scalp)
Bowel inflammation
Muscle pain
Vitamin B9
Tetrahydrofolate is coenzyme for 1-C transfer/methylation rxns (i.e. thymidylate synthase for de novo pyrimidine synthesis)
Vit B9 Deficiency
Folate pool depleted in alcoholics and pregnancy
Deficiency in pregnancy —> neural tube defect (spina bifida)
Due to side effects of drugs such as Phenytoin, sulfonamides, methotrexate
Macrocyclic megaloblastic anemia
Homocysteinemia (CV disease, DVT, thromboembolism, stroke)
Vitamin B12
Cobalamin
Converted to coenzymes methyl or deoxyadenosyl cobalamin for:
- Homocysteine —> methionine (homocysteine methyltransferase)
- Methylmalonyl CoA —> succinyl CoA (Methymalonyl-CoA mutase)
Vitamin B12 deficiency
Deficiency from
- Pernicious anemia (most common)
- Chronic pancreatitis
- long term total vegetarian diet
- resection of terminal ileum
Clinical manifestations
- megaloblastic anemia
- neuropathic
- homocysteinemia (CV disease, DVT, stroke)
Vitamin C
Ascorbate
Cofactor for
-collagen synthesis (prolyl and lysyl hydroxylase)
-Dopamine —> norepinephrine (dopamine B-hydroxylase)
- Enhances Fe absorption in GI tract
- Antioxidant
Vitamin C deficiency
Deficiency from diet devoid of citrus fruits and green veggies
Scurvy
- poor wound healing, easy bruising
- perifollicular hemorrhaging, bleeding gums, anemia
- Increased bleeding time
- painful glossitis
Vitamin A
Retinol
Retinoic Acid
Vision and maintenance of epithelium
Vitamin A deficiency
Caused from extreme malnutrition and fat malabsorption and liver cirrhosis
Night blindness
Metaplasia of corneal epithelium
Xeropthalmia, follicular hyperkeratosis
Frequent infections (pneumonia, bronchitis)
Toxicity: Teratogenic in pregnancy
Forms Vitamin D
D2: ergocalciferol (from plants)
D3: cholecalciferol (sun or Vit D fortified milk)
Calcifediol: 23-hydroxy vit. D (storage form in liver)
- Calcitriol: 1, 25 dihydroxy vitamin D (ACTIVE VITAMIN D)
- formed in kidney in response to PTH function
Functions of Vitamin D
GI tract: induces synthesis of Ca2+ binding proteins, inc. phosphate absorption
Kidneys: stimulates reabsorption of Ca2+ and secretion of phosphate
Bone: acts upon osteoblast receptors —> osteoclasts activation —> bone resporption
Vitamin D Deficiencies
Childhood rickets (skeletal abnormalities)
Adults osteomalacia (fewer deformities)
- mild: Chvostek’s/ Trosseau’s signs
- severe —> hypocalcemic tetany
- breast fed only infants —> vitamin D deficiency
Rickets
- delayed growth
- pain in spine, pelvis and legs
- muscle weakness
- bowed legs
- thickened wrists and ankles
- breastbone projection