Test 2

• Lesions of the skin, mouth, GI tract, nervous symptoms
• Mal del la Rosa – a form of leprosy
• Associated with poverty and consumption of spoiled corn

• Food shortages during/after Civil War
• Reported case by ATL MD
• Associated with an insect vector
• Water soluble B

• The antipolyneuritis factor
• Found in yeast 
• •Prevented both beriberi and pellagra
• •Antipolyneuritis factor was unstable to heat
• •Could still prevent dermatitis in rodents
• Considered 2 substances  
• •A-N – Antineuritic factor (thiamin)
• •P-P – pellagra preventative factor

• ID slowed by two factors
• Influence of the germ theory of disease
• Lack of an animal model

• Observed that the diets were different
• Professional staff diet included milk and meat
• Secured funding to supply milk and meat to orphans
• Believed pellagra was caused by diet
• Needed to prove pellagra was not infectious

• Ingest/inject the biological fluids of pellagrins
• Oral supplementation with cysteine and tryptophan were effective treatments
• Still no animal model
• Unsophisticated research
• Nutrient deficiency can cause disease

• Dogs were fed a diet associated with humans afflicted with pellagra
• Black tongue disease – the necrotic degeneration of the tongue
• The identification of an animal model for pellagra led to further experimentation

• Yeast, wheat germ, liver prevented canine black tongue AND promoted recoveries in pellagra patients
• The human pellagra and canine black tongue curative factor is heat stable
• Can be separated from other B2 complex components

• Isolated nicotinamide from liver extracts with high anti-black tongue activity
• Nicotinamide and nicotinic acid cure canine black tongue

• Isolated nicotinamide from hydrogen-transporting coenzymes I and II
• Nicotinamide adenine dinucleotide
• Nicotinamide adenine dinucleotide phosphate

• Meats, poultry, fish
• Legumes, peanuts, enriched flours and grain products

• Bran, cereals - niacin esterfied to complex carbohydrates (niacytin)
• Niacin esterfied to peptides (niacinogens)
• Esterfied niacin is not readily bioavailable

• Tradition in food preparation - treated their corn with lime water - released bound niacin
• Consumption of coffee - roasting green coffee converts trigonelline to niacin

• Synthesized in the liver from tryptophan
• 2.75% of tryptophan is metabolized to nicotinic acid mononucleotide
• Converted to serotonin, melatonin, CO2 and H2O
• The rest is converted to quinolinate NAD(P)

• NE (niacin equivalent)
• 60 mg tryptophan = 1 mg niacin
• 1 NE = 1 mg niacin = 60 mg tryptophan
• Proteins average ~1% tryptophan
• A diet consisting of 100g protein/d could provide 16 mg NE
• Adult females - 14 mg NE
• Adult males - 16 mg NE

Impaired by diets deficient in vitamin B6, riboflavin 

• Removing phosphates 
• NAD or NADP -nonspecific pyrophosphatases> NMN -alkaline phosphatase> nicotinamide riboside -slow release> nicotinamide

NAD or NADP -glycohydrolase> nicotinamide

• Occurs primarily in the small intestine
• Sodium-dependent, saturable process
• Passive diffusion at higher non-physiological concentrations

• Occurs primarily in the small intestine
• Temperature & energy dependent
• Na+ - independent
• Dependent on extracellular pH

• By facilitated and simple diffusion
• In RBCs, an anion transport protein is involved in facilitated diffusion

• Preiss-Handler pathway
• Dietrich pathway

• NAD de novo pathway
• Tryptophan -> NAD
• Nicotinic acid -> NAD
• Occurs primarily in the RBCs of liver

• NAD salvage pathway
• Nicotinamide -> NAD
• Phosphoribosyl transferase= rate limiting enzyme
• Much simpler
• NAD inhibits nicotinamide phosphoribosyl transferase 

Nicotinamide -nicotinamidase H2O> nicotonic acid -> preiss-handler pathway

• Nicotinic acid and nicotinamide are reabsorbed by the kidney
• Metabolites are excreted in the urine

• Participates in oxidation/reduction reactions
• Coenzymes will be dehydrogenase/reductase
• NAD and NADP are parts of the intracellular respiratory mechanism
• Posttranslational modification of proteins
• -ADP-ribosylation of proteins

• Beta-oxidation of fatty acyl CoAs
• Oxidation of ketone bodies
• Degradation of carbohydrates
• Amino acid catabolism

• Reducing agent for steroid synthesis
• Reducing agent for fat synthesis

• Produces pellagra - dermatitis, dementia, diarrhea, death
• An antituberculosis drug (isoniazid) binds to pyridoxal phosphate (B6), reducing the activity of kynureninase
• Zinc deficiency affects pyridoxal phosphate synthesis

• Impaired tryptophan absorption (affecting niacin synthesis)
• Hyperaminoaciduria
• Pellagra
• Neurological changes
• Unabsorbed tryptophan is degraded in the intestine by microbial tryptophanase to pyruvate and indole
• Indole is a neurotoxin

• Failure to provide sufficient NAD to critical areas of the brain
• Nicotinamide oxidation is increased
• Greater excretion of metabolic products
• Responsive to 1g/d niacin

• Hartnup disease
• Schizophrenia

• 1g nicotinic acid 3x per day has been used to treat hypercholesterolemia and hyperlipidemia.
• Inhibits lipolysis in adipose tissue
• Inhibits LDL synthesis in the liver
• Lowers total serum cholesterol, lowers LDL, increases HDL

• Used with tryptophan - enhances the effect of tryptophan supporting brain serotonin levels
• Reduces urinary excretion of tryptophan metabolites

• Reduced the risk of developing insulin-dependent diabetes in high-risk subjects
• Reduced loss of pancreatic beta cell function

• Release of histamine and flushing
• Working via prostaglandin synthesis
• Liver injury
• Increased uric acid levels (niacin competes with uric acid for excretion)
• Itching
• Elevation of plasma glucose levels

No toxic effects, but does not reduce blood lipids

• Measurement of urinary N’ methyl nicotinamide (mg/g creatinine) following a 50 mg test dose of nicotinamide
• Measured during a period 4 to 5 hr after the test dose
• Deficient= <0.5 mg/g creatinine
• Marginal= 0.5 to 1.59 mg/g creatinine
• Adequate= >1.6 mg/g creatinine

• Dermatitis, dementia, diarrhea, death
• Begins with sunburn-type symptoms on face, neck, extremities
• Neurological symptoms include peripheral neuritis, paralysis of extremities, dementia or delirium
• GI symptoms include glossitis, cheilosis, nausea, vomiting, diarrhea

• Based on N-methyl-nicotinamide excretion in urine
• 12-16 mg NE/d - minimal level for metabolite excretion
• 11 mg NE/d - prevents pellagra
• 1 mg/day - urinary excretion level that represents barely adequate niacin intake but above the intake that results in clinical deficiency

• Increased energy utilization and growth of maternal and fetal compartments
• Increase of 3 mg NE/d
• 3 mg NE + 11 mg NE (EAR)
• For the RDA, a CV of 15% is used
• 18 mg NE/d

• 2.4 mg NE + 11 mg NE (EAR)
• 1.4mg preformed niacin secreted + 1 mg to cover energy expenditure
• 15% CV is used to determine the RDA
• 17mg NE/d

• No adverse effects - niacin in foods
• Adverse effects from supplementation, fortified foods, pharmacological doses
• Flushing - burning, tingling, itching sensation on face, arms, chest
• 30 to 1,000 mg/day within 30 min to 6 days after initial dose
• Nicotinamide does not produce flushing
• Caused by rapid rise in plasma concentrations
• Reduced when taken with food

• Hepatotoxicity - associated with 3-9 g/day doses
• -Levels used to treat hypercholesterolemia
• -Chronic doses - months to years
• Impaired glucose tolerance -levels used to treat hypercholesterolemia
• Ocular effects - 1.5 to 5 g/day
• -Few cases in the literature
• -Blurred vision, toxic amblyopia, macular edema, cystic maculopathy
• -Reversible and dose-dependent

• Flushing reactions - the patient changed the amount or form of niacin used, or withdrew from treatment
• 50 mg/day in several studies
• Uncertainty factor - 1.5
• 50 mg/1.5 = 35 mg/day

• Plausible explanation for a set of observed phenomena
• Acceptance relies on a preponderance of supporting evidence
• Not necessarily proven, but there’s a huge amount of evidence used to develop
• Won’t be tested

• Tentative supposition that is assumed for the purposes of argument or testing
• Used to generate evidence by which theories can be evaluated

• Involves the generation of theories strictly by observation
• Observation of the natural world
• Generation of ideas about how the natural world operates

• Involves the undertaking of experiments to test the truthfulness of hypotheses
• Generation of hypotheses using these generalizations
• Experimental testing of the hypotheses
• 2 key tools were the animal model and purified diet

• Discoveries in microbiology
• Disease is caused by germs (anthrax, etc.)
• Widely held for nutritional disease 

• Scurvy-Vitamin C
• Beriberi-Thiamin
• Rickets-Vitamin D
• Pellagra-Niacin

• Sore gums, painful joints, hemorrhages
• Prevented by consuming green vegetables or fruits
• Found in skeletal remains of primitive humans.
• Fatal if untreated
• Common in Northern Europe in Middle Ages
• Sailors
• Consume salt (preserved foods)

• Peripheral neuropathy, cardiac enlargement, edema
• Described in ancient Chinese herbals 
• Thought was caused by insufficient dietary protein, or by a relative excess of fat and carbs to protein
• White (dehulled) rice

• Deformation of long bones, swollen joints, enlarged heads
• Associated with urbanization/industrialization
• Growth plate is disrupted
• There’s not the appropriate deposition of calcium in the growth plate
• Northern latitudes (low sunlight)
• Cod liver oil (Baltic and North sea coasts)
• Consume few 'good fats'

• Disease associated with diet
• Recognized by ancient Greek, Roman, Arab physicians
• Treated with animal liver

• Natural truths are considered to be constant
• Purified diet

• Highly refined ingredients
• –Isolated proteins
• –Refined sugars/starches
• –Refined fats
• Known chemical composition
• Prepared repeatedly by different investigators to yield comparable results

• Testing a hypothesis in the context of the ‘real world’
• Use of a representation of that context
• –A model
• If you create the deficiency, you should have the similar effect as if treating it
• –Must be analogous to situations that cannot be studied directly

• Appropriate to the diseases of interest
• Initially discovered by chance
• Lead ultimately to the discovery of all the vitamins and their roles in metabolism
• Allows for investigations that are otherwise impossible or unthinkable in humans

• Recognition that certain diseases are related to diet
• Development of appropriate animal models
• Use of defined diets

• Dutch East Indies (Jakarta, Indonesia)
• Determine the cause of beriberi
• Expected to find a bacterium
• Observation – one day the chickens were too weak to stand
• -Continued for 5 months
• -Similar to symptoms of human patients with beriberi
• -Suddenly disappeared
• Polyneuritis within days of feeding polished rice
• Signs disappear following feeding of unpolished rice
• Beriberi was extractable with water or alcohol, dialyzable, easily destroyed with moist heat

• Feed animals purified diets alone – no survival
• Add milk to synthetic diet – mice survive

• Discovered - accessory growth factors; glutathione, tryptophan
• Independent of appetite
• Biologically active in very small amounts

• The study of substances that prevent deficiency diseases
• The study of accessory factors required by animals fed purified diets

• Found in rice husks, was nitrogenous
• An amine and vital (or pertained to life), he chose the term vitamine

• Antiberiberi
• Antirickets
• Antiscurvy
• Antipellagra

• Provided a new concept for interpreting diet-related phenomena
• Provides a new intellectual construct
• –Determining the causes of disease in no longer constrained by the germ theory

• Fat-soluble factor A - extracted from certain foods with organic solvents
• -Milk fat and egg yolk, not lard and olive oil
• Water-soluble factor B - extractable with water
• -Wheat, milk, egg yolk, not polished rice

• Animals fed fat-free diet – ocular disorders
• Ocular disorders prevented by feeding cod liver oil, butter, or fat-soluble A

• Normal growth in rats
• Prevention of polyneuritis in chicks
• Thought to be identical or contain Funk’s antiberiberi vitamine
• Prevents beriberi and pellagra
• Antipolyneuritis factor lost with heating

• Aneurin = thiamin +
• -Thought to be a single vitamin but was several B vitamins
• Animal model – the rice bird

• 2 g polished rice/d
• Polyneuritis evident within 9-13 days
• Delay onset of symptoms

Coenzyme of thiamin

• Unrefined cereal germs & whole grains
• Enriched flours & grains
• Meats, especially pork
• Nuts, legumes
• In nutritional supplements
• –Thiamin hydrochloride
• –Thiamin mononitrate salt

• Stable at pH <7
• Labile at neutral to alkaline conditions
• –Cleaves methylene bridge
• Heat labile
• Easily oxidized
• -Forms disulfides & thiochrome

• Oxidized thiamin
• UV-induced blue fluoresence used to measure thiamin levels in biochemical assays

• Rupture of methylene bridge
• Foods preserved with sulfur dioxide
• Found in preservative foods that have antimicrobial properties

• Sulfites
• -Intestinal bacteria convert (reduce) sulfates to sulfite
• Thiaminases
• Chastak paralysis
• Hydroxypolyphenols

• Bacterial
• -Exoenzymes
• –Cell surface
• -Also in ruminants
• -Fish/shellfish breaks
• -Heat-labile

• Neurological disorder in commercially raised foxes fed raw carp
• Remedy – cook the fish before feeding

• Coffee, tea, blueberries, Brussels sprouts, etc.
• Oxidize the thiazole ring
• -Formation of thiamin disulfide – not bioavailable

• In plants, thiamin exists in free form
• In animals, >95% is phosphorylated
• –Thiamin pyrophosphate (TPP)
• –Coenzyme form

• High affinity thiamin transporter
• SLC19A2
• In the intestine

• Thiamin transporter expression
• Liver, stomach, duodenum, jejunum > ileum, colon

• Rare
• Mutations in SLC19A2
• Don’t get uptake of thiamin?
• Rogers Syndrome
• Autosomal recessive mutation
• Thiamin deficiency
• Sensorineural deafness
• Diabetes mellitus
• Cardiomyopathy 
• Optic nerve atrophy
• Retinal atrophy
• High doses of thiamin reverse anemia and diabetes

• In portal circulation - free thiamin
• Most thiamin in blood is in cells (~90%)
• –Uptake by facilitated diffusion
• –Within red cells, thiamin is phosphorylated – TPP
• --Metabolic tracking

• Cell types have different transport capacity for thiamin
• High in hepatocytes, enterocytes
• Lower in erythrocytes
• Number or efficiency of transporter differs among the type of tissue

• The body contains ~30 mg
• Most in the body is in skeletal muscles (~50%)
• –Other organs include heart, liver, kidney, brain
• No real storage site

• Thiamin + ATP -thiaminokinase> TPP + AMP
• TPP + AMP -TDP/ATP phosphoryl transferase> TTP + ADP
• TTP -thiamin triphosphatase> TPP
• 80% of total thiamin in the body is TPP

• Excess is metabolized for urinary excretion
• Cleavage of methylene bridge
• –Form the pyrimidine ring and thiazole
• --Further metabolized- 20 or more metabolites are formed

• Catalyze the oxidative decarboxylation
• Transketolations
• Nerve function
• TPP-dependent decarboxylases
• –Multienzyme complexes with FAD and NAD

• Pyruvate to acetyl CoA
• α-ketoglutarate to succinyl CoA
• α-keto acids from branched-chained amino acids to their acyl CoAs
• Branched chain amino acids -> valine, leucine, isoleucine 

• Hexose monophosphate shunt
• Transketolase

• Electrical stimulation -> TPP and TTP released from axonal membranes
• Found in mammalian brain, synaptosomal membranes
• Pyrithiamin (antagonist) changes electrical activity
• GABA shunt

• Increased in brains during thiamin deficiency
• A source of energy during thiamin deficiency
• Thiamin deficiency induces recovery pathway to maintain energy -> GABA shunt
• Increased GABA in hypothalamus causes anorexia
• –A characteristic of thiamin deficiency

• Don’t have TPP
• Independent decarboxylation to form GABA
• a-ketoglutamate -transamination> glutamate -decarboxylation> GABA
• Beriberi
• Wernicke-Korsakoff syndrome

• Catalytic activity in Na+ permeability
• Maintains negative charge on the inner surface of the membrane

• Muscle wasting
• Atrophy of the legs with peripheral neuritis
• Usually no cardiac involvement
• Inactivity
• Caloric restriction
• Paralytic or nervous
• Histology – degeneration of myelin in the muscular sheaths -> but without inflammation
• Generally occurs in physically inactive patients when caloric intake is poor

• Edema
• Cardiac hypertrophy
• Lung congestion
• Cardiac involvement

• 1. Peripheral vasodilation
• 2. Edema
• 3. Myocardial injury

• High cardiac output
• Renal salt & water retention
• Renin-angiotensin-aldosterone system in the kidneys

• The kidneys detect a relative loss of volume and respond by conserving salt
• With the salt retention, fluid is also absorbed into
• the circulatory system
• The resulting fluid overload leads to this` of the
• dependent extremities

• Hypertrophy
• Tachycardia
• High arterial/venous BP

• Subclinical thiamin insufficiency
• Associated with excessive alcohol consumption
• 25% cured with thiamin supplementation

• Paralysis of motor nerves of the eye
• Nystagmus - rhythmic oscillations of eyeballs
• Ataxia – no muscular coordination
• Psychosis
• Confabulation - readiness to answer any question fluently with no regard to facts
• Impaired retentive memory and cognitive function

• Low binding  affinity for TPP
• Can be overcome by high intramuscular doses of thiamin

• Intake antagonizes thaimin in 2 ways
• -Diets low in thiamin
• -Alcohol inhibits the intestinal ATPase involved in absorption

• Large consumption of raw fish (thiaminases), polished rice
• Antagonists- coffee, tea
• Alcohol

• Selected indicators
• -Urinary thiamin excretion
• -Erythrocyte transketolase activity
• -Erythrocyte thiamin
• –None of these indicators, by themselves, were used to estimate the thiamin requirement

• Erythrocyte transketolase activity 16-20%
• -Deficiency <20%
• Erythrocyte thiamin 70-90
• -Deficiency >70
• Urinary thiamin (creatine) 27-66
• -Deficiency <27
• Urinary thiamin 40-100
• -Deficiency <40

• Lack mitochondria
• No alternative means of generating NADPH
• –Pentose phosphate pathway
• NADPH is required to reduce glutathione
• –Maintains the normal structure of red blood cell
• –Maintains hemoglobin in the ferrous state
• Transketolase is a thiamine pyrophosphate-requiring enzyme, which catalyzes reactions in the pentose phosphate pathway
• -The level of transketolase activity in the red blood cell is a reliable diagnostic indicator of thiamine status

• Incubate with excess ribose 5-phosphate (or xylulose 5-phosphate)
• Excess added thiamine pyrophosphate
• Control that has no added TPP

• Measure the amount of substrate remaining and the amount of product formed
• -Use high performance liquid chromatography (HPLC), and a UV absorbance detector
• Enhanced enzyme activity resulting from the added thiamine pyrophosphate
• -The sample was originally deficient in thiamine
• -The extent of deficiency in thiamine is expressed in percent stimulation over the control value

• EAR - 1.0 mg/d (men) and 0.9 mg/d (women)
• RDA - 1.2 mg/d (men) and 1.1 mg/d (women)
• –Based on a CV of 10% because of lack of data to use the standard deviation

• Contained niacin, riboflavin and others
• Heat stable vs heat labile
• Water soluble
• Rat growth factor
• Isolated from liver, kidney, muscle, yeast

• Rats were fed a thiamin-supplemented diet
• –Exhibited growth failure
• When fed a thiamin-free extract – thrived
• –From yeast, liver, rice bran
• –Each extract exhibited a yellow-green fluorescence
• –Effect on growth was proportional to the intensity of fluorescence
• Isolated the fluorescence factor from egg white and from whey
• –Called it ovoflavin (egg)
• –Called lactoflavin (whey)

• ~70% is in the coenzyme form flavin adenine dinucleotide (FAD)
• In milk & eggs large amounts
• ~30% of the adult RDA is supplied by milk & dairy products
• Meats, especially liver, and green vegetables
• Enriched flour & breakfast cereals

• Gastric acidification/proteolysis release flavocoenzymes
• In upper small intestine, pyrophosphatases & alkaline phosphatase remove phosphate

• High affinity riboflavin transporter
• RTF1, RTF2, RTF3
• RFT1 & RTF2 – intestinal, placenta (RTF1), testes (RTF2)
• RTF3 – brain
• Concentrations <12 nM
• -Above= diffusion
• Saturable 
• Active
• Sodium-dependent

• Bile salts facilitate uptake
• A small amount is absorbed from the large intestine

• Albumin is the primary transport protein
• Other transport proteins include fibrinogen, immunoglobulins
• Estrogen-induced riboflavin-binding proteins for fetal uptake

• Metabolic Trapping
• -Riboflavin -ATP Zn2+ flavokinase> FMN
• FAD is formed fron FMN
• FMN-ATP Mg2+ FAD synthetase> FAD

• Oxidation/reduction reactions
• Energy production by the respiratory chain
• Protect cells from oxidative stress
• –Glutathione reductase
• –Methemoglobin reductases
• Ionic & hydrophobic interactions bind flavin coenzymes to proteins
• –Non-covalent interactions

• 8-α-N(3)-histidyl(peptide)-FAD
• 8-α-S-cysteinyl(peptide)-FAD
• Cannot resynthesize FMN or FAD
• Not nutritional sources for riboflavin

• Succinate dehydrogenase
• Sarcosine dehydrogenase
• N,N-dimethylglycine dehydrogenase

Monoamine oxidase

• Multiple acyl-CoA dehydrogenase disorder (MADD)
• Methylene THF reductase –  C677T

• FAD-dependent
• Catalyze the 1st step in β-oxidation of fatty acids
• Transfers electrons from oxidized fatty acids to the electron transfer protein complex
• ETFα, ETFβ, ETF dehydrogenase
• … to ubiquinone oxidoreductases
• Major source of energy for heart, skeletal muscle, liver
• Mutations in ETF
• –Less stable; reduced half-life

• Phenotype- neonatal cardiac defects and hepatic failure to adolescent myopathies
• Null mutation- most severe
• Missense mutations- responsive to riboflavin supplementation (sometimes)
• –100 mg/d + carnitine

• CVD, neural tube defects, Downs syndrome, congenital cardiac malformations, dementia
• Located in the FAD binding domain
• Decreased FAD binding; decreased enzyme activity
• Riboflavin supplementation increases enzyme stability

• The primary urinary metabolite- 60-70%
• Secretion in milk
• –Reason for milk being a major food source
• –Riboflavin is the highest (~50%); FAD (33%)
• –10-(2’-hydroxyethyl) flavin 
• –7-hydroxymethyl riboflavin

• Light sensitive
• Lumichrome & lumiflavin
• Light-excited flavin oxidizes nucleic acid bases of bacterial and viral pathogens

• Cheilosis- vertical fissuring, redness, swelling & ulceration of the lips
• Similar skin lesions with B6 deficiency
• -Impaired collagen formation
• -Decreased activity of pyridoxine 5’-phosphate oxidase
• --•Requires FMN
• --•Converts PMP to PLP
• May reduce synthesis of niacin from tryptophan

• Eborrheic dermatitis
• Soreness and burning of lips, mouth, tongue
• Photophobia
• Burning, itching eyes
• Superficial vascularization of cornea
• Cheilosis, angular stomatitis, glossitis, anemia, neuropathy

• Reduced dietary intake
• Congenital heart disease
• Cancer
• Excessive alcohol intake
• Increased excretion - diabetes mellitus.
• Amish newborns – hyperbilirubinemia
• -Treated with phototherapy

• Decreases protection from oxidative stress - malaria
• Plasmodial growth causes oxidative stress
• Riboflavin-deficient erythrocytes are susceptible to lipid peroxidation- lyse before the trophozoites mature

• Erythrocyte glutathione reductase
• Erythrocyte flavin 
• Urinary excretion of riboflavin

• Activity coefficient- ratio of activity in the presence and absence of added FAD
• < 1.2 = acceptable
• 1.2 to 1.4 = low
• > 1.4 = deficient

• Measure riboflavin
• > 400 nmol/L cells = adequate
• < 270 nmol/L cells = deficient

• Low = 50 to 72 nmol/g creatinine
• Deficient = <50 nmol/g creatinine
• Sufficient intake is 1.1 mg/d

• EAR - clinical deficiency and biochemical values relative to intake
• Men = 1.1 mg/d; women = 0.9 mg/d
• RDA - set by using a CV of 10%
• Men = 1.3 mg/d; women = 1.1 mg/d

0.3 mg/d added to adult EAR

• 0.3 mg/d is transferred to the milk
• 70% efficiency of riboflavin usage in milk
• 0.4 mg/d is added to the EAR

• No reported adverse effects from riboflavin consumption
• Up to 400 mg/d with meals for 3 months
• Limited capacity for absorption, rapid excretion
• -Max absorbed from a single dose is 27 mg
• -Oral riboflavin is used as a fecal marker in clinical studies
• No UL has been set

• Liver
• Soybeans
• Egg yolk
• Cereals
• Legumes
• Nuts
• Protein bound
• -Biocytin or biotinyllysine
• Also produced by colonic bacteria
• -Can get a small amount
• Avidin

• Glycoprotein in raw eggs
• Binds irreversibly to biotin
• Heat labile
• Can be used to follow certain molecules around
• Used to bind to cell surfaces

• Requires proteolytic digestion
• Yields free biotin, biocytin, biotinyl peptides
• Biotinidase functions on the intestinal brush border
• Will cleave the lyicine and remove 

• Primarily from small intestine
• -Duodenum > jejunum > ileum
• Some absorption from the proximal & midtransverse colon
• Na+-dependent multivitamin transporter

• Absorbed in the small intestine by passive diffusion
• Slower than biotin/Na+-dependent multivitamin transporter

• Free (80%) or protein-bound biotin in plasma
• Albumin
• α- & β-globulins
• Plasma biotinidase

A small amount is stored in muscle, liver, brain

• Na+-dependent multivitamin transporter
• Actively transported across the blood-brain barrier
• 2.5-times the plasma concentration
• Renal reabsorption

• Activated biotin - biotinyladenylate
• -Activated in order for it to bind to carboxylated enzymes
• Biotin-dependent enzymes - carboxylases 
• -Substrate picks up CO2 to produce a carboxylated product

• Acetyl CoA carboxylase
• Pyruvate carboxylase
• Propionyl CoA carboxylase
• β-methylcrotonyl CoA carboxylase

• Forms malonyl CoA from acetate
• Commits acetate units to fatty acid synthesis

• Holocarboxylase synthetase deficiency
• Biotinidase deficiency

• Citrate increases polymerization
• CoA lowers the Km for acetyl CoA
• High insulin:glucagon favors dephosphorylation
• The substrate for the formation of malonyl CoA 
• Increase insulin will activate enzyme

• Products of fatty acid synthesis depolymerize
• Will cause the dissociation of units
• Low insulin:glucagon favors phosphorylation (inactivates)

• Converts pyruvate to oxaloacetate
• Replenishes OAA for Krebs cycle necessary for gluconeogenesis
• Role in maintaining OAA and other intermediates for energy metabolism
• Anaplerosis
• Activated by pyruvate and acetyl CoA 
• Increased in the liver due to diabetes and hyperthyroidism

Replenishmentof intermediates in a metabolic cycle that may be depleted by removal from the cycle

• Accumulation of pyruvate
• Elevated lactate in blood
• Elevated alanine in bood
• Transamination
• A form
• B form

• Presents postpartum (months)
• Mild to moderate psychomotor retardation, lactic acidemia
• Causes severe mental retardation
• Most die within first few years
• Majority of cases in Algonkian linguistic group of Native Americans

• Presents postpartum
• Severe lactic acidemia, elevated blood ammonium
• Death within 3 months

• Converts propionate to succinate
• Provides mechanism for metabolism of some amino acids and odd-numbered chain fatty acids
• Succinate formed enters Krebs cycle
• Formation of methymalonyl CoA will ulitmately form succinyl CoA and enter the citric acid cycle
• Enzyme activity not regulated by substrate/product
• Not altered by dietary or hormonal changes

• Propionic acidemia
• Severe ketosis
• Metabolic acidosis
• Neurological complications
• -Seizures
• -Developmental delay
• -EEG abnormalities
• Elevated causes elevation of other metabolites
• Causes loss of carnitine
• In equilibrium with propionylcarnitine (excreted in urine)
• Elevated blood ammonium

• Exogenous Carnitine
• -Bind to propionyl CoA
• -Promote conversion of propionyl CoA to propionylcarnitine
• -Facilitate excretion of propionate
• Restriction of dietary protein
• -Low levels of isoleucine, valine, methionine, threonine

• Converts β-methylcrotonyl CoA to β-methylglutaconyl CoA
• Allows catabolism of leucine and certain isoprenoid compounds
• Not regulated by dietary or hormonal factors

• Elevated methylcrotonyl CoA
• Severe metabolic acidosis
• Low plasma glucose
• Low plasma carnitine
• Treated with carnitine 
• Moderate restriction of dietary protein

• Single gene defect affects all 4 carboxylases
• Elevated Km for biotin
• Have lower biotin affinity
• Treated with biotin supplementation
• Diagnosed prenatally
• Treated in utero with 10 mg biotin per day

• 1 in 112,000 births
• Wide variability of symptoms
• Responsible for cleavage

• Present weeks to years after birth
• Skin rash
• Hair loss
• Seizures
• Hypotonia
• Ataxia- problem with balance
• Developmental delay
• Hearing loss
• Optic atrophy
• Sufficient biotin to fully biotinylate carboxylases in utero

• Due to:
• Differences in dietary free biotin
• Residual biotinidase activity

• 10 mg biotin per day
• Amelioration/correction of symptoms
• -Metabolic acidosis
• -Skin rash
• -Regrowth of hair
• -Development
• No effects on hearing loss and optic atrophy

• Proteolytic catabolism of biotin holoenzymes or holocarboxylases yields biocytin
• -Biocytin is degraded by biotinidase to yield biotin
• -β-oxidation of the valeric side chain yields bisnorbiotin
• Excretion occurs in the urine
• Free biotin may be reabsorbed by the kidney
• Unabsorbed biotin is excreted in the feces

• Bisnorbiotin (major metabolite)
• Biotin sulfoxide
• Biotin sulfone
• Biocytin
• All lack side chains

• Depression
• Hallucinations
• Muscle pain
• Anorexia
• Hair loss
• Scaly dermatitis

• Individuals eating raw eggs
• Individuals with GI disorders
• Inflammatory bowel disease
• Achlorhydria
• Excessive alcohol consumption
• No toxicity reported

• Urinary biotin, bisnorbiotin and 3-hydroxyisovaleric acid
• -Urinary biotin and bisnorbiotin decreases, and urinary hydroxyisovaleric acid increases with consumption of raw egg whites
• Plasma biotin is not a sensitive indicator

• An Adequate Intake is established of 30 µg/d for adults 19 y & older
• Inadequate data to suggest an EAR & RDA
• No adverse effects
• No UL established

• Widely distributed in nature
• Contained in its various forms
• Coenzyme A
• Coenzyme A esters
• Acyl carrier protein
• Supplemental form – calcium pantothenate

• 85% is in food as a component of coenzyme A (CoA)
• Degraded to pantothenic acid for intestinal absorption
• CoA, phosphopantetheine, dephospho-CoA cannot be absorbed

• Jejunum
• Saturable Na+-dependent multivitamin transporter
• Na+-electrochemical gradient
• Pantetheine 
• -Hydrolyzed in intestinal cells

• Pantothenate in plasma, serum, & RBCs
• Primarily in RBCs
• Low concentration in plasma (0.06-0.08 mg/L)
• May be the form available for tissue uptake

• Na+-dependent multivitamin transporter
• Blood-brain barrier – saturable but not Na+-dependent

• All biosynthetic enzymes reside in the cytosol
• Most of CoA is in mitochondria
• Pantothenate kinase
• Fatty acid synthase ACP domain

• Pantothenate -> 4′-phosphopantothenate
• Inhibited by intermediates and end products
• 4’-phosphopantothenate, dephospho-CoA
• CoA, acetyl-, propionyl-, malonyl-CoA

• Covalent attachment of phosphopantetheine by a transferase
• ACP hydrolase releases ACP from fatty acid synthase

• Regulated by malonyl CoA concentration
• Regulated by activity of acetyl CoA carboxylase (biotin)
• As malonyl CoA increases, it’ll affect this

• Pyruvate dehydrogenase
• -TPP, NAD+, FAD+, CoA 
• α-ketoglutarate dehydrogenase complex

• Succinyl CoA and other acyl CoA
• Catabolic pathways for amino acids
• Glutamate, proline, arginine, histidine

• Valine, isoleucine, leucine
• Form α-keto acids after transamination
• Oxdatively decarboxylated
• Form branched chain acyl CoA products

• Fatty acids CoA -> acetyl CoA
• Carnitine palmitoyltransferase-I
• Carnitine palmitoyltransferase-II
• Sequential removal of 2-carbon segments as acetyl CoA
• Controlled by rate of transport of fatty acids into mitochondria

• Fatty acyl CoA -> acyl carnitine
• On outer mitochondrial membrane
• Inhibited by malonyl CoA

• Regenerates fatty acyl CoA
• On inner mitochondrial membrane

• Increased plasma free fatty acids 
• Inhibits acetyl CoA carboxylase
• Decreases malonyl CoA
• Increases fatty acids into mitochondria

• Acetoacetate
• 3-hydroxybutyrate

• Isoprenoid
• -Ubiquinone (coenzyme Q)
• Dolichol (glycoprotein synthesis)
• Cholesterol
• Steroid hormones
• Bile acids
• Is going to be a substrate for many different products including cholesterol

• Protection from proteolysis
• Compartmentalization

• CoA is dephosphorylated; the final product is pantothenate
• Pantothenate is excreted in the urine
• Reflects dietary intake
• Urinary excretion <1 mg/d - deficiency is suspected
• -Thought to correspond to an intake of <4mg/d

• Associated with severe malnutrition, impaired absorption
• Abnormal skin sensations
• Burning feet syndrome
• Vomiting
• Fatigue
• Weakness

• Alcoholics (low intake)
• Diabetes mellitus (increased excretion)
• Inflammatory bowel disease (impaired absorption)

• None reported to date
• Intake of 100 mg may increase niacin excretion
• Intake 20 g - mild intestinal stress & diarrhea

• Plasma pantothenic acid concentrations <100 mg/dL reflects low pantothenate intakes
• Urine pantothenate concentrations <1 mg/d is considered low

• Adequate Intake is 5 mg/d for adults 19 y & older
• Not enough data to establish an estimated average requirement (EAR) or an RDA
• AI’s were set for all age groups
• No UL established
• No reports of adverse effects from oral pantothenic acid