Water Soluble Vitamins Flashcards
Characteristics of water soluble vitamins
- Generally not “stored” in body
- (B12 = exception)
- Chronic intakes do alter tissues levels
- Toxicity usually low
- (B6 = exception)
- Absorption usually high
- Excretion typically via urine
Major B vitamins
- Thiamin (B1)
- Riboflavin (B2)
- Niacin (B3)
B vitamins: Biochemical/physiologic fxn
–All involved in glycolysis/Krebs cycle
–TPP, FAD, NAD; decarboxylation, oxidation-reduction
Thiamine: biochemial fxn
- Coenzyme for rx central to intermediary metabolism in all cells
- esp. glycolysis, TCA cycle, amino acid metabolism
- PDH coenzyme
Riboflavin (B2): Biochemical fxns
- Part of coenzymes: FAD & FMN are dervied from B2
- Glycolysis
- TCAC
Vit B3: Biochemical fxns
- Constituent of NAD & NADP
- Energy pathways
- Glycolysis
- TCAC
Folate: Biochemical fxns
- Important in 1-carbon transfers
- think about epigenetics and gene expression in current research
Vit B12: Biochemical fxns
- Closely related to folate metabolism and 1-carbon transfers;
- Odd chain length fatty acid
- catalyze isomerization of methylmalonyl Co-A to succinyl Co-A (essential to lipid and CHO metabolism).
Thiamine (B1): Physiologic Metabolic Role
- Decarboxylation and transketolation reactions;
- functions in nerve conduction
- Thiamin pyrophosphate (TTP) thought to bind at Na+ channel @ n. membranes
Riboflavin (B2): Physiologic Metabolic Role
- Oxidation/reduction reactions in Krebs cycle & oxidative phosphorylation
- Amino acid & FA metabolism
- Vit K, Folate B6 & B3 metabolism
Niacin (B3): Physiologic Metabolic Role
- Glycolysis, Kreb cycle
- oxidative phosphorylation
- FA synthesis & oxidation
Folate: Physiologic Metabolic Role
- Synthesis of nucleic acids and for metabolism of certain amino acids
- conversion homocysteine → methionine
Thiamine (B1): Major dietary sources
- Whole & enriched grains
- Lean pork
- Legumes
Riboflavin (B2): Major dietary sources
- Dairy + Animal Products
- Wheat germ, Almonds,
- Leafy greans
Niacin (B3): Major dietary sources
- RDA: 14-16 mg/d
- Dairy
- Eggs
- Enriched breads and cereals
- Fish
- Lean meats
- Legumes
- Nuts
- Poultry
Folate: Major dietary sources
Foliage → deep green leaves, broccoli, orange juice, whole grains (easily destroyed with prolonged cooking)
Thiamine (B1): Characteristic deficiency findings
- Triad: ocular, ataxia, mental confusion/amnesia
- Beriberi (think: Ber1ber1 for B1)
- Dry berberi → peripheral neuropathy,
- Wet berberi → edema, CHF
- Cerebral berberi → Wernicke- Korsakoff
Riboflavin (B2): Characteristic deficiency findings
- Oral-ocular-genital syndrome:
- 2 Cs:
- Corneal vascularization
- Cheilosis/stomatitis → cracks at angles of mouth
Niacin (B3): Characteristic deficiency findings
- Pellagra 4Ds → dermatitis, dementia, diarrhea, death
- Rash is scaly, has areas of depigmentation and hyperpig, photosensitive.
- Glossitis.
Folate: Characteristic deficiency findings
- Macrocytic anemia, hypersegmented neutrophils
- glossitis, irritability
- increased plasma homocysteine
- Neural tube defects
Vit C (Absorbic Acid): Biochemical fxns
- Antioxidant/
- Reducing agent → electron donor
- Co-substrate in hydroxylation:
- collagen synthesis
- (C = collagen)
- Reduction of Fe3+ → Fe2+ (absorption)
Vit C (Absorbic Acid): Physiologic Metabolic Role
- Collagen Synthesis
- NT synthesis:
- trp → serotonin
- dopa → NE
- Iron absorption
- Leukocyte fxn
Vitamin B12 (cobalamin): Characteristic deficiency findings
- Macrocytic anemia, hypersegmented neutrophils.
- Neurologic disturbances: paresthesias, gait problems, depression, dizziness, burning tongue
- initially reversible, irreversible eventually
Vitamin C: Characteristic deficiency findings
Scurvy: swollen gums, bruising, anemia, poor wound healing, weakness, aching joints / bones/ muscles, hemorrhagic signs
Loss of precursors of catecholamines & other vasoactive & neurotropic substances
Vitamin B12: Major dietary sources
- Animal products only
- Eggs
- Meat
- Milk
- Poultry
- Shellfish
Vitamin C: Major dietary sources
- fruits
- veggies
Thiamine (B1): Risk for deficiency/toxicity
- Alcoholics
- Anorexia
- Bariatric surgery
Riboflavin (B2): Risk for deficiency/toxicity
- Women, infants, elderly, adolescents
- Diets lacking major sources
- Sub-clinical deficiency: oral contraceptives, elderly, eating disorders, etc.
Niacin (B3): Risk for deficiency/toxicity
- Nutritional restriction, malabsorbtion,
- alcoholism
- metabolic shunting
Folate: Risk for deficiency/toxicity
- Premature infants, pregnancy
- Alcoholics
- Chronic hemolytic anemia or blood loss
- Medications:
- Phenytoin (seizures)
- sulfasalazine (IBD)
Vitamin B12: Risk for deficiency/toxicity
- Pernicious anemia
- Gastric atrophy
- Resection of stomach or ileum
- Strict vegan diet
- Breastfed infant of deficient mother
Vitamin C: Risk for deficiency/toxicity
- Infants fed cow’s milk without supplementation
- Diets lacking in fruits and vegetables,
- ↑ requirements of vit C for wound healing & burns;
- Low income → associated with poor diet quality;
- Smokers
Summary Table of Vit Deficiency Sx
