Nutrition Flashcards
Vitamin B1 (thiamine)
What is it’s function? What are the findings with deficiency? Diagnosis?
Function: Thiamine pyrophosphate (TPP) is a cofactor for dehydrogenase enzyme rxns: Pyruvate dehydrogenase (pyruvate-> acetyl CoA), alpha-ketogluterate dehydrogenase (TCA cycle), transketolase (HMP shunt), branched-chain ketoacid dehydrogenase
Deficiency:
Wernicke-Korsakoff- confusion, ophthalmoplegia, atazia, personality change, memory loss,
Dry beriberi- polyneuritis, symmetrical muscle wasting
wet beriberi - high output cardiac failure (dilated cardiomopathy), neuropathy, edema
Seen in malnutrition and alcoholism
Diagnosis: observed increase in RBC transketolase activity after B1 administration
Vitamin A (retinol)
What is the function? What are the causes and findings in: deficiency? Excess?
Function: antioxidant,
Vitamin B2 (riboflavin)
Source: Dairy products
Function: Component of flavins FAD and FMN-> cofactors in redox reactions-dehydrogenases (ex: PDH, glutathione reductase, succinate dehydrogenase in TCA cycle)
Deficiency: Cheilosis (inflammation of lips, scaling and fissures at corners of mouth) and Corneal vascularization
Vitamin B3 (niacin)
Source: liver, milk, grains
Function: Constituent of NAD+ and NADP+ (B3=3ATP); Derived from tryptophan and requires B2 and B6 for synthesis. Used to treat dyslipidemia-> lowers VLDL and raises HDL
Deficiency symptoms: Glossitis; Pellagra (Diarrhea, Dementia, Dermatitis ‘broad collar rash’), hyperpigmentation of skin
Deficiency caused by: Malignant carcinoid syndrome (increased tryptophan metabolism), Isoniazid (decreased B6), Hartnup disease (decreased tryptophan absorption)
Excess: causes excess prostaglandin action -> facial flushing, pruritis, hives, nausea, vomiting (avoid by taking aspirin); Hyperglycemia, Hyperuricemia
Vitamin B5 (pantothenic acid)
Function: Component of coenzyme A (CoA) and fatty acid synthase
Deficiency: rare, Dermatitis, enteritis, alopecia, adrenal inusfficiency
Vitamin B6 (pyridoxine)
Source: meat, eggs, wheat
Function: Is converted to PLP (pyridoxal phosphate) which is a cofactor for transamination (ALT, AST), decarboxylation reactions and glycogen phosphorylase, synthesis of cystathionine, heme (deltaALA rate-limiting step), histamine, NTs (5HT, Epi, NE, DA, GABA)
Deficiency: Convulsions, hyperirritability, peripheral neuropathy, sideroblastic anemias (impaired Heme synthesis and iron excess)
Deficiency etiology: inducible by isoniazid and OCP
Vitamin B7 (Biotin)
Source: nuts
Function: Cofactor for carboxylation enzymes (add 1C)
- Pyruvate carboxylase (pyruvate 3C -> OAA 4C)
- Acetyl-CoA carboxylase (acetyl-CoA 2C -> malonyl CoA 3C)
- Propionyl-CoA carboxylase: (propionyl-CoA 3C -> methylmalonyl-CoA 4C)
Deficiency: rare, dermatitis, alopecia, enteritis; Caused by antibiotic use or excessive raw egg white ingestion (avidin binds biotin)
Vitamin B9 (folate)
Source: fruits and leafy greens
Absorbed in jejunum, small reserve pool in liver
Function: Converted to THF, coenzyme for 1C transfer (methylation rxns) -> important for synthesis of bases in DNA and RNA
Deficiency: Macrocytic megaloblastic anemia; hypersegmented PMNs; glossitis; No neuro symptoms
Deficiency labs: Elevated homocysteine, normal methylmalonic acid
Deficiency causes: Alcoholism, pregnancy, drugs (phenytoin, sulfonamides, methotrexate)
Vitamin B12 (cobalamin)
Source: animal products, Large storage in liver -> takes years to develop deficiency
Function: transfers methyl groups; cofactor for homocystein mehtyltransferase and methylmalonyl-CoA mutase
Deficiency: Macrocytic megaloblastic anemia, hypersegmented PMNs, paresthesias and other neuro effects from abnormal myelin
Labs in deficiency: Increased homocystein and methylmalonic acid levels
Deficiency causes: veganism, malabsoprtion (sprue, enteritis, D. latum), lack of IF (pernicious anemia, gastric bypass surgery), or absence of terminal ileum (Crohn disease)
Diagnosis of pernicious anemia= anti-IF antibodies
Vitamin C (ascorbic acid)
Function: antioxidant, reduces iron to Fe2+ state. Necessary for hydroxylation of proline and lysine in collagen synthesis and for Dopamine beta-hydroxylase (DA -> NE)
Deficiency: Scurvy- swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, ‘corkscrew’ hair
Excess: GI distress, fatigue, calcium oxalate nephrolithiasis. Can increase iron toxicity in individuals with high iron levels (transfusions, hemochromatosis)
Vitamin E (tocopherol/tocotrienol)
Source: sunflower oil, corn oil, meat, soybeans, fruits and vegetables
Function: Antioxidant- protects against free radical damage. Can enhance anticoagulant effects of warfarin (inhibit vitamin K)
Deficiency: Hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract demyelination
Neuro presentation similar to B12 deficiency, but w/out megaloblastic anemia, hypersegmented PMNs or increase in MMA levels
Zinc
Function: minear essential for a bunch of enzymes, important for zinc fingers (TF motif)
Deficiency: Delayed wound healing, hypogonadism, decreased adult hair, dysgeusia (distortion of taste), anosmia, acrodermatitis enteropathica, may increase risk of alcoholic cirrhosis
Kwashiorkor
Protein malnutrition -> skin lesions, edema (decreased plasma oncotic P), liver dysfunction (fatty change from decreased apolipoprotein)
Clinical picture: small child w swollen abdomen
Marasmus
Total calorie malnutrition -> muscle wasting, loss of subQ fat, variable edema
Effects of excess EtOH consumption
Increased NADH/NAD+ ratio from metabolisim in liver ->
- pyruvate -> lactate (lactic acidosis)
- OAA -> malate (prevents gluconeogenesis, fasting hypoglycemia)
- DHAP -> glycerol-3-P (combines w/ FA to make triglycerides -> hepatosteatosis)
- Favors TCA production of NADH -> increased ketogenesis (ketoacidosis) and lipogenesis (hepatosteatosis)
