B Vitamins and Iron

what is vitamin B1 converted to & what is it used for?

Thiamine; role in synthesis of nerve-regulating substances (ex: nerve cell function & metabolism)

indications of vitamin B1

prophylaxis of B1 deficiency, Beriberi and Wernicke's encephalopathy

what group is at risk for vitamin B1 deficiency?

alcoholics; can't absorb it as well

what can vitamin B1 deficiency lead to?

brain damage (in thalamus, midbrain, brainstem)

-manifests as Wernicke-Korsakoff syndrome (visual disturbances, ataxia, tremors, impaired memory)

what condition is associated with alcoholism and vitamin B1 deficiency?

Wernicke-Korsakoff Syndrome

where is vitamin B1 stored? where is it metabolized? where is it excreted?

-stored in heart, liver, skeletal muscle, kidneys, and brain

-hepatic metabolism

-excreted in the kidney

is B1 deficiency common?

No - flour and cereal products are enriched w thiamine

2 forms of vitamin B2

riboflavin 5 phosphate and flavin adenine dinucleotide

what do the forms of vitamin B2 do?

play a role in ATP production; metabolism of carbs, fats, and proteins

indications for use of vitamin B2?

generalized deficiency; typically with other B vitamins

-can be used for reducing symptoms of fatigue, cataract symptoms, and migraine/headache symptoms.

where is B2 absorbed? where is it distributed? where is it excreted?

-absorbed in upper ileum

-widely distributed in tissue (not really stored)

-excreted in urine

side effect of B2 supplements?

yellow/orange discoloration of sweat, urine, and potentially breastmilk

another name for vitamin B3

niacin

what is B3/niacin converted into?

NAD and NADP

what are NAD and NADP used for?

coenzymes used for lipid and protein metabolism

what is an indication for vitamin B3 use?

hypercholesterolemia

-utilized OTC and prescribed for high cholesterol

how does B3 work to lower cholesterol?

niacin decreases VLDL (very low density lipoprotein) synthesis while increasing HDL (high density lipoprotein

-VDL (bad cholesterol)

-HDL (good cholesterol)

side effects of niacin

flushing (can be accompanied with pruritus and tingling), hepatic dysfunction, GI side effects, reduced glucose tolerance

how can you offset flushing side effect of niacin?

taking aspirin 30 mins prior to ingestion OR use of extended release niacin

can B3 be sourced through diet to lower cholesterol?

can be sourced through diet but NOT enough to lower lipids

what is vitamin B6?

pyridoxine

indications for vitamin B6 use

morning sickness/nausea, sideroblastic anemias, off-label for PMS

importance of vitamin B6?

essential for production of vitamin B12 and folate; necessary for absorption and metabolism of amino acids

what can vitamin B6 counteract?

drug toxicity (isonazid - TB, mushrooms, ethanol)

Importance of vitamin B12 and folic acid

-play roles in DNA synthesis

-Folic acid affects synthesis of purines/pyrimidines/amino acids

indications for vitamin B12 use:

-pernicious anemia

-megaloblastic/macrocytic anemias caused by poor B12 absorption

indications for folic acid use:

-megaloblastic and macrocytic anemias

-prevention of neural tube defects in neonates (incidence rate decreased by >50% with FA use)

-adjunct to methotrexate toxicity

-pernicious anemia in combo with vitamin B12

what is the primary complication caused by deficiency of B12 and Folic acid?

anemia

what is another result of vitamin B12 deficiency?

abnormal DNA replication leading to large, dysfunctional RBC precursors

-can also affect the nervous system (inflammation, demyelination, neuronal cell death, neuropathy)

what is used to facilitate absorption of B12?

gastric intrinsic factor; pH sensitive

why can't gastric surgery patients absorb B12 well?

decreased/deficient levels of gastric intrinsic factor

what cells secrete gastric intrinsic factor?

parietal cells

how do you treat patients with parietal cell disruption?

IM (intramuscular) B12 - bypasses intrinsic factor

what group of people are at higher risk for vitamin B12 deficiency?

vegetarians

What pathways are important for folic acid?

methionine and homocysteine metabolism

what can result due to folic acid deficiency?

high incidence of neural tube defects and anemia

what group of people should take folic acid supplements?

women of childbearing age

what is an indication for iron supplement use?

prevention of and treatment of iron deficiency anemia

how is iron normally taken? alternative method of administration?

PO

-IV can be used for noncompliant patients or those who can't tolerate oral treatment

what is a concern over IV iron administration?

anaphylaxis-like reactions

causes of iron-deficiency anemia

-malnutrition

-chronic blood loss (menstruation, GI bleed, cancers)

-increase utilization of iron (pregnancy)

examples of PO iron

ferrous sulfate (MOST COMMON)

-ferrous fumarate, ferrous gluconate, polysaccharide-iron complex

examples of IV iron

iron dextran, sodium ferric gluconate, iron sucrose

Iron Mechanism of Action

-RBCs contain majority of iron in hemoglobin

-Old RBCs are taken up by reticular system (spleen/macrophages) and are relieved of their iron

-transferrin delivers iron to liver (storage) or BM (further hemoglobin/RBC production)

where can iron be stored in the body?

-hemoglobin

-myoglobin

-ferritin (main cellular storage protein)

-some also stored in protein deposits called hemosiderin

majority source of iron stores in the body?

hemoglobin and myoglobin (80%)

which is better absorbed - ferrous iron or ferric iron?

ferrous

where is ferrous iron sourced from?

animals (heme iron)

where is ferric iron sourced from?

vegetarian food (non heme iron)

consideration for when to take iron?

on empty stomach

what medications can decrease iron absorption?

antacids, H2 blockers (ex: pepcid), proton pump inhibitors (ex: prilosec), calcium supplements

what can be combined with iron for better absorption?

vitamin C (ascorbic acid)