water soluble vitamins Flashcards
what are the functions of thiamin (Vitamin B1)
Thiamine Diphosphate (TDP or thiamin pyrophosphate TPP): coenzyme central to intermediary metabolism in all cells, esp. glycolysis, TCA cycle, amino acid metabolism; decarboxylation; transketolation reactions; TTP thought to bind at Na+ channel in nerve membranes; many function in nerve conduction
what are the rich Food sources for Thiamin (B1)
whole grains (high in germ), enriched grains, lean pork, legumes
whar are the Requirements/intake recommendations for thiamin (B1) :
RDA: 1.1-1.2 mg/d.
what is the Treatment for Thiamine deficiency:
50-100 mg intramuscular or intravenous.
deficiency in Thiamin can cause:
Beriberi (3 types)
1) dry (paralytic/nervous) beri beri
2) wet (cardiac) Beri Beri
3) Wernicke-Korsakoff syndrome (cerebral beriberi)
what are the symptoms of Dry (paralytic/nervous) beriberi:
peripheral neuropathy w/ impairment of sensory, motor, and reflex functions; affects distal > proximal limbs; muscle tenderness, weakness/ atrophy, foot/wrist drop
what are the Sx’s Wet (cardiac) beriberi
edema and high output cardiac failure (tachycardia, cardiomegaly and CHF) + signs/sxs of dry beriberi
what are the Sx’s of Wernicke-Korsakoff syndrome (cerebral beriberi):
“Triad”
1) ocular signs (nystagmus, ophthalmoplegia),
2) ataxia (lack of muscle control or coordination of voluntary movements),
3) amnesia/mental confusion
what are the biochemical evaluations for Thiamine deficiency?
Erythrocyte transketolase activity; blood thiamine levels
which populations are at risk for thiamine deficiency
Alcoholics most at risk in US (low intake, poor intestinal absorption, defective metabolism);
Elderly: relatively high incidence of mild deficiency; Chronic renal dialysis patients;
adults on high carbohydrate diet, ;
Refeeding after starvation
Bariatric surgery (assoc. w/ bypass, banding, and gastric sleeve).
what are the Functions of RIBOFLAVIN (B2):
Part of 2 co-enzymes, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) which function in oxidation/reduction reactions in TCA cycle and oxidative phosphorylation. Amino acid & fatty acid metabolism; metabolism of vit K, folate B6, niacin.
what are the richest food sources of RIBOFLAVIN (B2)
liver, wheat germ;
Dairy = largest contribution to intake in US diet (UV light destroys the vitamin), meats & poultry; leafy greens
what are the Deficiency signs of Riboflavin (B2):
oral-ocular-genital syndrome -
cheilosis (cracked lips),
angular stomatitis (sores at corner of mouth),
increased vascularization of conjunctiva and photophobia,
seborrheic dermatitis and scrotal dermatitis.
water soluble vitamins are Generally not “stored” in body except for _____ .
B12
Breast milk reflects maternal intake/status of water soluble vitamins except _____
folate
what are the functions of NIACIN (B3)
Nicotinamide is substituent of the electron carrying substances NAD & NADP
what are the Food sources for niacin
Meats, poultry, fish, peanut butter, legumes are major sources of preformed niacin. Tryptophan = precursor; diets w/ liberal amounts of milk and eggs (rich in tryptophan) are likely adequate for niacin, even if low in preformed niacin.
what are the symptoms of Niacin deficiency
Dermatitis: characteristic symmetric pattern, scaling w/ areas depigmentation & hyperpigmentation, aggravated by sun, heat exposure
Dementia: confusion, dizziness, and hallucinations
Diarrhea
Death
In Niacin (B3) Deficiency, what are the Predisposing Factors
1) Nutritional/dietary restriction Cornmeal (w/o germ) based diet (esp w/o alkaline/lime treatment)
2) Malabsorption syndromes
3) Alcoholism
4) Metabolic “shunting” (ie. carcinoid tumor w/ ↑ serotonin -> decreased tryptophan
which vitamins are the hematopoietic vitamins
Folate and B12
what are the functions of folic acid?
single C transfers
nucleic acid synthesis
amino acid metabolism
DNA Methylation – regulation of gene expression / epigenetics
what are the food sources of folate
“foliage,” deep green veg
orange juice
whole grains
who are at risk for folate deficiency
Inadequate intake or increased destruction in food
Alcoholics
Pregnancy
what are the signs and sx’s of folate deficiency?
Macrocytic anemia *Hypersegmented neutrophils *Glossitis, irritability *Homocysteinemia Neural tube defects (occurrence/recurrence
Women of child bearing age advised to have intake of ____ to prevent neural tube defects
400-800 micro grams/day*
what are the functions of Vitamin B12 (cobalmin)
Reform tetrahydrafolate from methylfolate (synthesis of methionine)
Catabolism of odd chain length fatty acids
Catalyze isomerization of methylmalonyl Co-A succinyl Co-A (lipid & CHO metabolism)
Vitamin B12 that is Transported in circulation is called ____
Transcobalamin II
Vitamin B12 has large _____ stores and is primarly excreted via _____
liver,
bile
What are the risk factors for B12 deficiency?
Inadequate IF secretion or antibodies to IF
Gastric atrophy/gastrectomy
Ileal resection
Breastfed infant of B12 deficient vegan mother
what are the effects of B12 deficiency?
Macrocytic anemia & hypersegmented neutrophils
Neurologic disturbances: depression, paresthesias, gait disturbances, burning tongue, dizziness
What are the 6 Functions & Physiologic Roles of Vitamin C (Ascorbic Acid)
1) Reversible antioxidant, Vitamin E sparing
2) Provides reducing equivalents to enzymes:
Reduction of iron so increases absorption
3) Conversion dopamine to norepinephrine
4) Leukocyte function ( Increased [AA] wbc)
5) Co-substrate inCollagen synthesis: hydroxylation of proline & lysine; cross-links for tropocollagen
6) Hydroxylation of tryptophan to serotonin
what are the sx’s of Vit C deficiency (scurvy)
1) Hemorrhagic signs (Bleeding gums, ecchymoses, petechiae)
2) Hyperkeratosis of hair follicles + perifollicular hemorrhages
3) Hypochondriasis: depression, weakness
4) Hematologic abnormalities
Anemia: iron &/or folate deficiencies, bleeding
what is the progression of scurvy
weakness, aching joints/bones/muscles, hemorrhagic signs
Benefits of “megadoses” Vitamin C ?
may reduce duration of cold sx’s
good for wound healing
