Vitamins and Nutrition Flashcards
Vitamins
Small molecules important as cofactors in many biological/enzymatic reactions
Deficiency
Due to either inadequate diet, inadequate GI absorption, competing organisms (e.g., parasites)
Insufficiency
Due to increased metabolism that mandates intake and absorption of greater than normal levels
Toxicity
Abnormally high intake that can lead to pathology (mostly leading to either hepatic or kidney damage)
Vitamin B1 other name and function
- Thiamine
- Coenzyme for energy metabolism
Vitamin B2 other name and function
- Riboflavin
- Precursor for coenzymes FMN or FAD, redox reactions
Vitamin B3 other name and function
- Niacin
- Precursor to coenzyme NAD, dehydrogenase reactions
Vitamin B5 other name and function
- Pantothenic acid
- Component of Coenzyme A
Vitamin B6 other name and function
- Pyridoxine
- Aa metabolism and transport, heme synthesis
Vitamin B7 other name and function
- Biotin
- Coenzyme for carboxyl unit transfer
Vitamin B12 other name and function
- Cyanocobalamin
- Hematopoiesis, fatty acid metabolism
Folate/folic acid (vit B9) function
Coenzyme for one-carbon transfer reactions and aa metabolism
Vitamin C (ascorbic acid) function
- hydrogen ion transfer
- redox reactions
- aa metabolism
- collagen synthesis
Vit A (retinol) function
- Vision
- Cell differentiation
- Growth
- Reproduction
- Immune system function
Vitamin D function
controls calcium and phosphate metabolism
Vitamin E function
- Antioxidant
- Peroxide breakdown
- Cellular integrity
Vitamin K function
Cofactor for post-translational carboxylation of many proteins and clotting factors. Give Vit K shots to newborns to aid clotting
Biochemically, vitamins are most easily studied within groups defined by ___
hydrophobicity
List fat-soluble vitamins
A, D, E, K
Water soluble-vitamins
Vit C
B1, B3, riboflavin, B5, B6, B7, B12
Fat soluble vitamin solubility properties
- Dissolve in fat before bloodstream absorption
- Process requires bile acids from the liver
- Carried by lipoproteins
Vit E carried by which lipoprotein?
LDL
Fat soluble vitamins mainly stored where? Where do they go if not stored?
- Intestines, liver, and fatty tissues
- Greater risk of toxicity due to storage
- Excreted in feces if not stored
Water soluble vitamin storage and elimination
- Not stored in body, so less chance of toxicity
- Regularly eliminated in urine and feces
- Constant re-supply needed
Water soluble vitamin toxicity
Less chance of toxicity BUT impaired secretion in renal damage
Major site of vitamin absorption
Small intestine
Vitamin metabolism pathway
- Nutrients enter at cellular level
- Picked up and absorbed by blood capillaries and lymph fluids thru active transport/diffusion/osmosis
Where are Vitamin B12 and Vitamin K metabolized?
Large intestine
List most commonly assayed vitamines
- Folate (Vit B9)
- Vit B12
- Vit D
ID the vitamin
Most common vitamin deficiency
Can lead to megaloblastic anemia
Folate (Vit B9)
Which pathologies depend on normal folate levels (feature folate deficiency)?
- Megaloblastic anemia
- Neural tube defects
- Increased levels of atherosclerosis related to homocysteine turnover on appropos vitamin levels
Folate tested on which sample types?
Serum and RBC hemolysate
ID the vitamin
Absorption dependent on Intrinsic Factor
Associated with megaloblastic anemia/pernicious anemia
Transcobalamins transport this vitamin
Vit B12 (cyanocobalamin)
Vit B12 testing
Serum or plasma
Similar to folate assays
T/F
Lots of foods contain Vit D
False
Vit D important for assessing what?
- parathyroid function
- bone development
- chronic renal failure
- monitoring vit D therapy
- vit D toxicity
- small bowel disease
- pancreatic insufficiency
- drug-related hypovitaminosis
Vit D from the diet or skin synthesis is biologically ___
inactive
What is required for Vit D activation?
Enzymatic conversion in liver and kidney
Marasmus
- Diet deficient in both protein and calories
- Most severe -> general wasting
Kwashiorkor
- Diet adequate in calories but deficient in protein
- Less severe than marasmus
- Visceral muscle protein loss but no skeletal muscle loss
Negative outcomes of malnutrition
- Increased mortality/morbidity
- Impaired wound healing
- Increased rate of infection
- Increased length of hospital stay
Lab methods to assess nutritional status
- selected protein markers most useful
- hematology assays (Hgb, Hct, WBC, lymphs)
- immunology assays (increased TDT, cytokine levels)
- non-protein chemistry (vitamin analysis, BUN/creatinine, cholesterol/triglyceride, mineral levels)
List protein markers used to assess nutritional status
- transferrin
- pre-albumin (transports T4 and retinol)
- retinol-binding protein (RBP) (vit A transport)
- albumin/aa/IGF-1/leptin
T/F
One single protein marker can assess overall nutritional status
False, need more
Protein markers may provide info on:
- metabolic status
- determining prognosis
- monitoring of nutrition support
Useful protein combo to assess nutritional status
Plasma markers (usually pre-albumin/transthyretin) + acute phase reactant like CRP
What does the following indicate:
Normal CRP
Low pre-albumin
Protein malnutrition
What does the following indicate:
Significantly increased CRP
Low pre–albumin
There may be false decrease in pre-albumin
What CRP and pre-albumin lab results indicate improving protein nutrition status?
Decreasing CRP and increasing pre-albumin
Total parenteral nutrition (TPN)
Necessary if GIT not properly functioning or when patient cannot take anything by mouth
TPN complications
- fluid/electrolyte imbalance
- acid-base imbalance
- glycosuria
- hyperglycemia
- liver/hematologic abnormalities
- vitamin/mineral deficiencies
