Water Soluble Vitamins Flashcards
Beriberi
- Thiamin B1 Deficiency
- “Dry” = peripheral neuropathy; muscle tenderness, weakness & atrophy; foot drop
- “Wet” = edema, circulatory collapse, CHF
- Wernicke-Korsakoff (cerebral beriberi): confusion, opthalmoplegia, ataxia, memory loss
Food sources for thiamin riboflavin, and niacin
Thiamin: pork, legumes
Riboflavin: dairy, eggs, meats
Niacin: meat/poultry; tryptophan = precursor
- All involved in glycolysis/Krebs cycle
- TPP, FAD, NAD; decarboxylation, oxidation-reduction
Risk for thiamin deficiency
- Alcoholics
- s/p bariatric surgery
- TPN
- Anorexia nervosa
- re-feeding
- endemic in So Asia
What physical symptoms do you get from B2 deficiency?
Riboflavin deficiency
- Cheilosis
- Angular stomatitis
What does B3 deficiency lead to?
Pellagra
- Malabsorption syndromes
- nutritional/dietary restriction
- Alcoholism
- Metabolic shunting (carcinoid tumor)
4 D’s of Pellagra
- Diarrhea
- Dermatitis (scaling w/ areas of depigmentation and hyperpigmentation; aggravated by sun exposure - Casal’s necklace)
- Dementia
- Death
Folic Acid
Function: Single C transfers for DNA methylation
Food sources:
- foliage, deep green veg
- orange juice
- whole grains
Situations with risk of folate deficiency
- inadequate intake or increased destruction in food
- alcoholics
- pregnancy
- hematopoietic conditions
- drug/nutrient interactions
Signs of folate deficiency
- macrocytic anemia (inc. MCV)
- hypersegmented neutrophils
- glossitis, irritability
- homocysteinemia
- NTD
How much folate should be taken to prevent NTD
400-800 micrograms/day
Vitamin B-12
- Forms tetrahydrafolate from methylfolat (synthesis of methionine)
- catabolism of odd chain length fatty acids
- catalyze isomerization of methylmalonyl Co-A to succinyl Co-A (lipid and CHO metabolism)
- methylation
- interactions essential for homocysteine –> methionine, protein synthesis, nucleic acid synthesis
Absorption of B12
- Cleave vitamin from dietary protein in stomach
- Requires IF from stomach
- Cobalamin-IF complex absorbed in distal ileum
- Transport into circulation with transport protein transcobalamin II
Food sources for B12
- soil bacteria
- animal products
vegans should take a supplement
Risk factors for B12 deficiency
- Inadequate IF secretion or antibodies to IF
- gastric atrophy/gastrectomy
- ileal resection
- breastfed infant of B12 deficient vegan mother
Effects of B12 deficiency
- macrocytic anemia & hypersegmented neutrophils
- neurologic disturbances (depression, paresthesias, gait disturbances, burning tongue, dizziness)
Vitamin C
Function:
- Reversible antioxidant, Vit E sparing
- Provides reducing equivalents to enzymes (reduction of iron –> inc. absorption
- Leukocyte function (inc. [Vit C] wbc
- co-substrate in hydroxylation –> collagen synthesis
- conversion dopamine –> NE
Sources of Vit C
F/V
Absorption of Vit C
- Active (saturable) process
- Low intake = 100% absorption
- Typical intake (30-180 mg/d) = 70-90% abs.
- Megadoses reduce your efficiency
If you take large doses, better to take them in divided doses for better absorption
- Renal excretion limits plasma levels
- intakes of 400-500 mg –> no inc. plasma concentration
Pool sizes of vit C
- 10 mg/d
- 1500 mg: maintained w/intake = prevents scurvy x 30-45 days with no intake
- 2300-2800 mg: acheived with 200mg/day + unmetabolized vit C in urine
Scurvy in kids
- Autistic children on restricted diets
- Refuse to walk
- Gingival hypertrophy
Benefits of megadoses of vit C?
- Prevent common cold? (antihistamine effects, neutrophil chemotaxis; dec duration symptoms
- Prevention of CVD, Ca (RCT do not support F/V)
- Wound healing: inflammation, proliferation, maturation
