fnu 404 Anemias- b's, thiamin, riboflavin, niacin, B6, pantothenic acid, biotin, vitamin C

megaloblastic anemia

folate deficiency

pernicious anemia

vitamin B12 deficiency due to lack of intrinsic factor

homocysteine is increased with

folate and B12 deficiency

schilling test

distinguished pernicious anemia from other causes of B12 deficiency

folate deficiency anemia symptoms

weakness and pallor, degeneration of surface mucosal tissue allowing mucosal ulceration and possible infection. sore tongue, GI disturbances, diarrhea, and malabsorption

in folate deficiency anemia, there are decreased

WBCs and platelets

etiology of folate deficiency anemia

poor diet of low animal products, low green vegetables, alcoholic, tea and toast of "elderly", poor intestinal absorption, increased metabolic demands of late pregnancy, growth (early infancy), concurrent vit. C deficiency

good sources of folate include

dark green vegetables, liver, kidney, yeast

folate is easily destroyed by

inadequate handling, storage, and exposure to heat

sources of B12

meat, milk, and eggs

etiology of B12 deficiency anemia

deficient in strictest vegetarian diet, lack of intrinsic factor, heredity, gastrectomy, small bowel disease

food sources of thiamin

pork, whole grains, enriched cereals, liver, poultry, fish, eggs, potatoes, legumes, nuts, dark green vegetables, brewer's yeast, and wheat germ

thiamin is easily

destroyed by heat and alkalinity

thiamin exists in

free form in plant foods

thiamin in animal foods is primarily as

thiamine diphosphate or thiamine pyrophosphate

thiamin must be phosphorylated in

intestine

the absorption of thiamin is

usually high

thiamin phosphates are digested to yield

free thiamin

absorption of thiamin

occurs primarily in the jejunum, secondarily in the duodenum and ileum

what reduces thiamin absorption?

alcohol

thiamin is transported by an

active, sodium- dependent mechanism

thiamin is transported _______ , bound to ______________ , or as ________________ __________________

free, albumin, thiamine monophosphate

thiamin functions

energy production and nutrient metabolism (coenzyme role), synthesis of pentoses and nicotinamide adenine dinucleotide phosphate (NADPH), nervous system functions

functions of thiamin

metabolism and release of energy from carbs, oxidative decarboxylation of a- ketoacids and 2-keto sugars, conversion of pyruvate to acetyl CoA, reactions in the krebs cycle, anti- inflammatory, pentose phosphate pathway, membrane conduction of nerve tissue, branched- chain amino acid metabolism

thiamin is excreted _____________ or _______________.

intact, catabolized

beriberi

thiamin deficiency (mental confusion, muscular problems, cardiac disorders, CNS problems, anorexia, and fluid imbalance)

there is no tolerable upper intake level of

thiamin

wernicke- korsakoff syndrome

thiamin deficiency (clinical triad of confusion, ataxia, and nystagmus)

riboflavin is important in

energy metabolism

what are the 2 coenzyme forms of riboflavin?

Flavin mononucleotide (FMN)
Flavin adenine dinucleotide (FAD), which are both involved in the transfer of electrons.

riboflavin is

light sensitive; sunlight

dietary sources of riboflavin

milk, dairy, leafy green vegetables, liver, beef, meat, enriched cereals, and grains

riboflavin as FAD, FMN, and riboflavin phosphate are

freed prior to absorption

riboflavin is absorbed by

energy- dependent transporter in proximal small intestine

FAD and FMN are released in the

upper part of the small intestine

riboflavin is absorbed by a

saturable, sodium- dependent transport system

bile salts facilitate the uptake of

riboflavin

riboflavin is transported in the plasma bound to

albumin or other blood proteins

riboflavin is phosphorylated to _____ and then dephosphorylated back to ___________.

FMN, riboflavin

riboflavin is transported to liver for conversion to _____ and _____.

FMN and FAD

the greatest concentrations of riboflavin are found in

liver, kidney, and heart

riboflavin is excreted

primarily in urine

riboflavin turns urine a

bright orange- yellow color

functions of riboflavin

facilitation and the release of energy from carbs, protein, and fat. krebs cycle activity, electron transfer mechanisms, accepting electrons in biochemical reactions, flavoproteins in the ET chain, vitamin B6 metabolism and choline catabolism, used by l- amino oxidase, oxidative decarboxylation of pyruvate, succinate dehydrogenase, fatty acid B- oxidation, coenzyme for an oxidase such as xanthine oxidase, synthesis of folate as 5- methyl THF, synthesis of niacin from tryptophan, gluathione, thioredoxin, ribonucleotide reductases, some neurotransmitters

ariboflavinosis

riboflavin deficiency (angular stomatitis, cheilosis, glossitis, hyperemia, edema

riboflavin has no

tolerable upper intake level established

deficiency conditions of riboflavin

suppressed energy release, nervous system failing to properly glean energy, photophobia, poor coordination, cheilosis, inflammation of the mouth, waxy skin, anorexia

pellagra

niacin deficiency disease

coenzyme forms of niacin

nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP)

food sources of niacin

brewer's yeast, fish, pork, beef, poultry, mushrooms, potatoes, some plants, dairy foods, enriched cereals, and grains

nicotinic acid can be formed from

tryptophan in humans

digestion and absorption of niacin

digested to nicotinamide, most absorption in the small intestine, absorbed by sodium- dependent and saturable, facilitated diffusion mechanism and by some simple passive diffusion (larger concentrations)

niacin is found in

fish, meats, and enriched grain products

niacin is supplemented as

nicotinamide

1 mg niacin= how much tryptophan?

60 mg tryptophan

niacin digestion, absorption, transport, and storage

NAD and NADP hydrolyzed to free nicotinamide, absorbed in small intestine, absorbed mostly by sodium- dependent, carrier- mediated diffusion, transported primarily as nicotinamide and as nicotinic acid, found trapped as NAD/ NADP in cell

4 D's of pellagra

dermatitis, diarrhea, dementia, death

large doses of niacin are used to treat

hyperlipidemia

UL for niacin

35 mg per day

niacin functions

involved with numerous enzyme reactions, reduction/ oxidation reductions, glycolysis, krebs cycle, b- oxidation, alcohol metabolism, electron transport chain, pyridoxal metabolism, donor of ADP ribose in chromosomes, component of glucose tolerance factor, fatty acid synthesis, cholesterol synthesis, steroid hormone synthesis, synthesis of deoxynucleotides for DNA, reduction of dehydroascorbic acid to ascorbic acid

NAD+ and NADH+ has a significant role in

mitochondrial health and age- related disorders

niacin influences

insulin secretion, gluconeogenesis, mitochondrial biogenesis, endothelial function, lipid metabolism, cell cycling, and apoptosis

niacin controls

fatty acid metabolism and protection from oxidative stress

pharmacologic use of niacin

lowers total blood cholesterol, LDL cholesterol, and triglyceride levels

large doses of niacin may produce

toxic effects

there are six chemical forms of ________ existing in humans.

vitamin B6

dietary sources of B6

pyridoxine is found in plant foods, such as bananas, navy beans, and walnuts.

pyridoxal and pyridoxamine and their phosphorylated derivates are found in

animal products, meat, fish, and poultry

in vitamin B6 digestion, absorption, and metabolism, phosphate groups are

removed during digestion

absorption of the nonphosphorylated form of vitamin B6 takes place by

diffusion

absorption of B6 is

efficient

liver is the primary organ for

B6 metabolism

what is the main circulating form of vitamin B6?

PLP

PLP is transported either within cells

RBCs or bound to albumin

pyridoxal 5' phosphate (PLP) is the active coenzyme form of

vitamin B6 and the most common measure of B6 blood levels in the body

functions of vitamin B6

transamination reactions, deamination and decarboxylation reactions, creation of nonessential amino acids, transulfhydration and desulfhydration reactions, formation of neurotransmitters, breakdown of glycogen, heme production and iron incorporation into heme, sphigolipid and phospholipid synthesis, immunity

deficiencies of vitamin B6 are

rare

various drugs can cause deficiencies of

vitamin B6

alcohol can destroy some

vitamin B6 structures

vitamin B6 supplements can decrease the

duration and intensity of anticonvulsant drugs (dilantin)

raw egg white can bind

biotin

biotin is a stable vitamin in

heat and light

biotin is widespread in foods, but excellent sources include

organ meats, eggs, yolks, brewer's yeast, legumes, nuts, soy flour, soybeans, whole grains, and some fish

avidin in egg whites will bind biotin and

decrease its availability for absorption

biotin is either free or

bound to proteins

biotin is absorbed by

facilitative diffusion (Na- dependent)

biotin deficiency is

rare, but marginal status is possible with the chronic consumption of raw eggs.

cooking eggs denatures

avidin

biotin is excreted by

urinary filtration

biotin is stored in

muscles, brain, and liver tissue

biotin is needed to metabolize

carbohydrates, fatty acids, and leucine

biotin may play a role in other reactions involving

amino acids and purine synthesis

inborn errors of metabolism may produce biotin deficiency. the main symptom is

dry, scaly skin with a gray hue

symptoms of biotin deficiency

loss of epithelial cells, atrophy of tongue and GI tract cells, anorexia, nausea, alopecia, growth retardation, hearing and visual loss, metabolic acidosis, and elevated blood ammonia

pantothenic acid was first identified as a

growth factor for yeast and an antidermatitis factor in chicks

pantothenic acid is the

active form and is a structural component of coenzyme A

pantothenic acid is

stable in air and light

pantothenic acid is readily destroyed by

heat, alkali, and acid pH

pantothenic acid is widespread in

foods

excellent sources of pantothenic acid include

organ meats, egg yolks, meats, fish, whole grain cereals, legumes, mushrooms, broccoli, avocados, and royal jelly (from bees)