water soluble vitamins

Question 1

general facts

Answer 1

not stored in the body (b12 exception)
chronic intakes do alter tissue levels
toxicity usually low (B6 exception)
Absorption usually high
Excrete via urine
breast milk reflects maternal intake (folate is exception)

Question 2

Thiamine (B1) function

Answer 2

Thiamine Diphosphate (TDP or thiamin pyrophosphate TPP)- coenzyme for rglycolysis, TCA cycle, amino acid metabolism; specifically in decarboxylation and transketolation reactions; TTP thought to bind at Na+ channel in nerve membranes; many function in nerve conduction

Question 3

Riboflavin B2

Answer 3

“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, and niacin.”

Question 4

Niacin B3

Answer 4

Nicotinamide is substituent of the critical electron carrying substances * NAD & NADP*; functions in multiple energy related pathways, including glycolysis, TCA cycle and oxidative phosphorylation and fatty acid synthesis and oxidation.

Question 5

Folate

Answer 5

1-carbon transfers, esp. in synthesis of nucleic acids and for metabolism of certain amino acids; conversion homocysteine → methionine

Methyl-donor, epigenetics

Question 6

Vit b12 (cobalmin)

Answer 6

”- Closely related to folate metabolism 1-C transfers;

• Metabolism of odd chain length fatty acids;
• Re-form THF from methylfolate (in formation of methionine);
• Isomerization of methylmalonyl Co-A to succinyl Co-A (essential to lipid & CHO metabolism).
• Interaction essential for protein & nucleic acid synthesis.
• Absorption and Homeostasis*: - Cleavage of vit from dietary protein & binding to “intrinsic factor” (IF) secreted by gastric parietal cells. 
-Cobalamin - IF complex absorbed from distal ileum. Absorbed into portal circulation, transported bound to transcobalamin II.
• Liver stores 1-10 mg* (vs RDA!); Can take years to develop deficiency, unless damage to stomach, ileum, pancreas”

Question 7

Vit B6

Answer 7

critical in amino acid metabolism, interconversions

Question 8

Vit C

Answer 8

antioxidant/reducing agent (=electron donor); 

Collagen synthesis;
reduction of Fe3+ → Fe2+ & enhanced Fe absorption; Norepinephrine synthesis

Absorption & Homeostasis: Through active (saturable) process; dose dependent: at low doses ( 1.5 g/d, absorption ~50%; at 10 g/d, absorption ~15 %. ∴

*** if large total intake, better to take divided in 80 mg/d; maximum pool size ~ 2000 mg; intakes > 400-500 mg/d → minimal further increase in plasma a.a. concentrations.
“

Question 9

Neuro symptoms

Answer 9

Vit E, Niacin, Vit B12, Vit B6, Vit C

Question 10

Anemia

Answer 10

B12, folate, vit b6, vit C, vit E, Vit K

Question 11

Mouth lesions

Answer 11

folate, vit b6, vit b12, vit C, riboflavin

Question 12

rash/skin findings

Answer 12

niacin, vit C, vit A, vit K

Question 13

energy releasing vitamins

Answer 13

Thiamine (b1)

Question 14

Thiamine sources

Answer 14

Esp. rich in whole grains (high in germ), enriched grains, lean pork, legumes

Question 15

Riboflavin B2 sources

Answer 15

“Richest sources: liver, wheat germ;
Dairy = largest contribution to intake in US diet (UV light destroys the vitamin),
meats & poultry;
leafy greens”

Question 16

Niacin B3 sources

Answer 16

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.

Question 17

Folate sources

Answer 17

“foliage” - deep green leaves, broccoli, orange juice, whole grains
(easily destroyed w/ prolong cooking); fortification of grains in U.S. in 1998 → ↑intakes

Question 18

Vit B12 sources

Answer 18

Animal products only!

Question 19

Vit B6 sources

Answer 19

animal products, vegetables, whole grains (lost in processing, not enriched)

Question 20

Vit C sources

Answer 20

“Fruits and vegetables: broccoli, green pepper, citrus, potatoes. 
US diet: 
39% from fruits, 15% potatoes,
38% other veg;
 > 80% vit C in Western diet from F/V 

(Paleolithic diet about 600 mg/d)”

Question 21

Deficiency Toxicity Vit C

Answer 21

• Scurvy*: defective collagen formation in capillary basement membranes & loss of precursors of catecholamines and other vasoactive and neurotropic substances.
• Symptoms: petechiae, bleeding gums, anemia, bruising; painful joints*

Question 22

Deficiency Toxicity Vit B6

Answer 22

anemia, seizures, glossitis; +/- depression?;
Risk of toxicity: doses > 500 mg/d associated with sensory ataxia, impaired position/vibratory sensation; symptoms partially reversed with d/c of supplement

Question 23

Deficiency Toxicity Vit B12

Answer 23

Macrocytic anemia, hypersegmented neutrophils, Neurologic disturbances: paresthesias, gait problems, depression

*Note: hematologic effects reversible, but neurologic effects are irreversible with longstanding deficiency. Treatment with folate will correct anemia but has NO effect on neurologic symptoms.

Macrocytic anemia should not be treated with folate unless B12 deficiency has been ruled out.

Question 24

Deficiency Toxicity Folate

Answer 24

Macrocytic anemia, hypersegmented neutrophils, glossitis,
↑ increased plasma homocysteine;
↑ occurrence & recurrence of neural tube defects; risk partly hereditary, partly polygenic;

Individuals w/ MTHFR gene ↑’s requirement

Question 25

Deficiency Toxicity Niacin B3

Answer 25

Pellagra: “The 4 D’s:”
Dermatitis: characteristic symmetric pattern; aggravated by sun, heat exposure (hypo and hyper pigmented areas
Dementia- confusion, dizziness, and hallcucinations
Diarrhea
Death

Toxicity: Relatively nontoxic in doses of 3 6 grams/d of nicotinic acid; used to lower serum cholesterol (esp LDL); initially causes peripheral vasodilation & flushing; less common: ↑ serum uric acid, glucose intolerance, liver damage.”

Question 26

Deficiency Toxicity Riboflavin B2

Answer 26

Deficiency signs: oral-ocular-genital syndrome - cheilosis (cracking of lips) and angular **stomatitis (sores at corner of mouth), **increased vascularization of conjunctiva and photophobia, and seborrheic dermatitis and ***scrotal dermatitis.

Question 27

Thiamine B1 deficiency

Answer 27

“Classical syndrome: Beriberi;
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
Wet (cardiac) beriberi: edema and high output cardiac failure (tachycardia, cardiomegaly and CHF) + signs/sxs of dry beriberi
Wernicke-Korsakoff syndrome (cerebral beriberi):
“Triad” – ocular signs (nystagmus, ophthalmoplegia), ataxia, and amnesia/mental confusion. Retentive memory impaired out of all proportion to other cognitive function; only partially reversible with pharmacologic doses of thiamin; genetic predisposition for different susceptibility, unmasked by EtOH abuse, dietary deficiency. Neuro sxs may be only partially reversible (ophthalmoplegia quickly responds)”

Question 28

which vitamins are involved in energy production

Answer 28

Thiamine, riboflavin, niacin

found enriched grains

Question 29

Berberi

Answer 29

dry-neuropathy muscle tenderness weakness atrophy foot drop.
wet- edema, circulatory collapse, CHF

wernicke korsakoff- ataxia, memory loss, opthalmoplegia, confusion

B1 deficiency

Question 30

who is at risk for B1 deficiency

Answer 30

alcoholics, bariatric surgery, TPN, anorexia, refeeding,

endemic in southeast asia

Question 31

6 mo old breastfed infant vomiting, opthalmoplegia, CHF

Answer 31

B1 deficiency (berberi)

Question 32

5 yr old eats burgers and milk, now limping and cant walk, rash

Answer 32

vitamin C (Scurvy)

Question 33

alcoholic found down altered mental status, anemic

Answer 33

Thiamine maybe b12

Question 34

15 mo old breast fed infant that doesnt want to walk, growth faltering

Answer 34

b12- baby not getting it in milk

Question 35

obese adolescentbariatric surgery, cant walk falls down

Answer 35

thiamine, maybe b12

Question 36

adult with rash and diarrhea

Answer 36

pallagra, niacin deficiency