Water soluble Vitamins Flashcards
Does chronic intake alter tissue levels?
yes
Toxicity?
usually low
B6 = exception
Absorption
usually high
Breast milk reflective of maternal status?
yes, except folate?
Excretion
via urine
Energy releasing
Thiamine
Riboflavin
Niacin
Hematopoietic
folic acid
B12
Non B complex
ascorbic acid vitC
Thiamine
Riboflavin
Niacin
function
all involved in glycolysis / TCA
Thiamine
Riboflavin
Niacin
sources
whole and enriched grains
Thiamin - legumes (decreased in polished rice)
Riboflavin - dairy, eggs, meat
Niacin: meat/poultry (tryptophan = precursor)
*corn is a poor source unless alkaline-treated
Thiamin deficiency
BeriBeri - Nervous and cardiovascular systems
Dry - peipheral neuropathy - weakness and atrophy
Wet - edema, CHF
Wernicke-Korsakoff (Cerebral) - confusion, ophthalmoplegia, ataxia, memory loss
Thiamin deficiency
who is at risk?
alcoholic voming s/p bariatric surgery TPN AN Re-feeding Endemic in So Asia - polished rice
Infantile beriberi
infant formula w/o thiamin
- vomiting / infection / lethargy / ophthalmoplegia / low thiamine PPi
Prompt response to high dose (50mg/d x 2wk)
Riboflavin deficiency
Cheilosis
Angular stomatitis
Low dairy, animal products, common in low resource setting
Niacin deficiency
Pellagra (D4) Dermatitis Dementia Diarrhea Death
Dermatitis in Niacin deficiency
scaling with areas of depigmentation and hyperpigmentation - aggrevated by sun
Niacin deficiency predisposing factors
Nutritional/dietary restriction
cornmeal based diet
Malabsorption
Alcoholism
Metabolic shuting (carcinoid tumor)
Folic acid (Folate) Functions
single carbon transfers
- nucleic acid synthesis
- amino acid metabolism
- epigenetics (methylation)
Folic acid (folate) sources
foliage -
orange juice
whole grains - enriched
easily destroyed in prolonged cooking
risk of folate deficiency
inadequate intake or increased destruction of food
alcoholics
pregnancy - globally higher rates
hematopoietic conditions
drug/nutrient interactions
folate deficiency
signs and symptoms
macrocytic anemia hypersegmented nuets glossitis irritability homocysteinemia (above are reversible) neural tube defects
folate supplementation
400-800microgram/day for women of child bearing age - to prevent neural tube defects
important pre-conceptus as neural tube closes 4-6wk gestation
VitB12 cobalamin
functions
reforms THF from methylfolate (necessary for synthesis of methionine)
catabolism of odd chain FA
isomerization of methylmolonyl CoA to succinyl CoA (lipid and CHO metabolism)
One carbon transfers (methylation)
METABOLISM INTIMATELY RELATED TO FOLATE
Interactions essential for homocysteine –> methionine, protein synthesis, nucleic acid synthesis
VitB12 absorption
stomach?
ilieum?
requires IF from stomach
Cobalamin-IF absorbed in distal ileum
Transport in circulation as transcobalaminII
VitB12
absorption
storage
excretion
enterohepatic circulation
large liver stores
excretion: primarily via bile
Vit B12 sources
only in animals
synthesized in soil bacteria
vegans should take supplement
B12 deficiency at risk?
inadequate IF or antibodies to IF
Gatric atrophy
Ileal resection
Breasfed infant of B12 deficienct mom
B12 deficiency effects?
Macrocytic anemia
Hyperseg nuets
nuerologic disturbance - depression / parasthesias / dizzy / gait
B12 deficiency
reversible effects?
Hematologic effects are reversible with B12 or folate
neurological effects eventually irreversible
MEGALOBLASTIC ANEMIA SHOULD NOT BE TREATED WITH FOLATE UNLESS B12 RULED OUT!!
Vitamin C
Functions
Cosubstrate in hydoxylation: collagen synthesis ; seratonin synthesis from typtophan
Converstion of Dopamine to norepinephrine
Reversible antioxidant
Reduction of iron –> increased absorption
Leukocyte function
VitC food sources
Fruits and Veggies US 39% F 15% Potatoes 38% other vegetables
VitC intake/absorption
Saturable
If taking large doses divid into <1g/dose
VitC absorption homeostasis
if you increase intake the GI will decrease absorption
Renal excretion limits plasma levels
Intakes of 400-500mg –> no increase in plasma concentration
VitC deficiency
Scurvy Hemmorhagic signs Hyperkeratosis of hair follicles Hypochondriasis Hematologic anomalies - anemia - iron or folate deficiencies
VitC deficiency progression
weakness - aching - joints - bones - muscles - hemorrhagic
Scurvy in children
Autism link
Benefits of megadoses of VitC?
Common cold - decrease duration of symptoms?
Wound healing -
6 mo old breastfed infant, vomiting, ophthalmoplegia, CHF
Beriberi - wet - Thiamin
5 year old eats only burgers with bun and milk, now limping and refusing to walk, with “rash”
Scurvy - vitamin C
Alcoholic “found down” altered mental and anemic
Could be thiamin or folate
Obese adolescent s/p bariatric surgery, can’t walk, falls down
Thiamin (BeriBeri)
Adult, low SES, chronic diarrhea, malabsorption, rash on arms, hands, neck
Niacin
