B Vitamins (B1, 2, 3, 5, 6 and BIOTIN)

[liveonearth]

B1, 2, 3, 5, 6 and BIOTIN

B VITAMINS AND ADULT REQUIREMENTS
1 THIAMIN 1.1-1.2 mg/day
2 RIBOFLAVIN 1.1-1.3
3 NIACIN 14-16 mg/day
5 PANTHOTHENIC ACID 5 mg/day
6 PYRIDOXINE 1.3-1.7 mg/day
12 COBALAMIN (mcg amount)
folic acid (mcg amount) and biotin (30mcg/day) don't have numbers anymore

GENERAL
original vit B discovered to have "subfractions"
originally extracted from: liver, yeast, rice bran
usu not all B's present in one food
B6 and 12 deficiencies common, also not in energy cycle
mostly non-toxic but niacin and B6 can be toxic
activation may require coenzyme fx of others, def sx can overlap (folate, B12)
therapeutic use of one does not increase requirements of others
human requirements vary significantly
many are abundant in west dt enrichment of refined grain products: thiamin, riboflavin, niacin

FUNCTIONS
essential for similar body fx:
mitochonrial energy production
THIAMIN: decarboxylation
RIBOFLAVIN: electron transfer (FAD<-->FADH)
NIACIN: ELECTRON TRANSFER (nad<-->NADH)
PANTOTHENIC ACID: coenzyme A rxnx
FOLIC AND B12: nucleic acid syn and methylation

LIMITS
No UL: thiamin, ribo, panto, biotin, b12
there is a UL for niacin and B6
niacin as tx to control cholesterol can lead to toxic doses

B1 = THIAMINE
mitochondrial energy production
transketolase for pentose phosphate pathway
provides ribose-5-phosphate for nucleotyde snthesis
transketolase activity in RBCs used to detect tissue def of thiamin
non-coenzyme fx in nerve, muscle-->neuropathies if def
more def in alcohol abusers
may cause: CHF, neuropathies, very low --> Wernicke's encephalopathy, vertical nystagmus

RIBOFLAVIN = B2
is fluorescent yellow, turns your pee yellow
energy metabolism, FAD<-->FADH using glutathione reductase which contains selenium
antioxidant function: regenerates reduced glutathoine
liver detox (p450 system)
DEF uncommon except in cases of chronic malnutrition: alcoholism, anorexia nervosa
marginal def in elderly
Sx are nonspecific: oral cheilosis, angular stomatitis, glossitis
Sx: skin: seborrheic dermatitis, eye--corneal vascularization, cataracts
tissue levels assessed with RBC glutathione activity
USE riboflavin to prevent cataracts (antiox rule)
USED to TX migraine headaches, cut down frequency/severity, high doses 400 mg

B3 = NIACIN
body can make niacin from tryptophan
stuctures: nicotinic acid = niacin, nicotinamide, coenzymes
nicotinic acid only in plants, large amounts cause flushing and lower cholesterol
is foreign chemical, changes liver processing of cholesterol
flushing response goes away after about 2 weeks of therapeutic dosing
doses used much more than what's found in food
nicotinamide = niacinamide found only in animal tissue, no vasodilate or chol effect
functions: mitochondrial energy production (NAD<-->NADH)
anabolic rxns: biosynthesis of fatty acids
DEFICIENCY
uncommon in west
Four D's of PELLAGRA: dermatitis, diarrhea, dementia, death
dermatitis on sun exposed areas only
SUPPLEMENTS
regular niacin is immediate release, blood levels change quickly, causes vasodilation
slow release causes more hepatotoxicity
niacinamide is esp safe, no flushing, no lowering of cholesterol
Life Extension no niacin flush, inositol hexaniacinate
PRESCRIPTION
NiaSpan for reduced side effects
take it at bedtime, once a day, extended release, one of the better options
SE: flush, heptaotox, GI irrit, headache, impaired glucose tolerance, elevated uric
avoid OTC sustained release niacin
LOOK OUT: DM, peptic ulcer dz, migraine, gout, cardiac arrhythmias
UL 35 mg/day based on avoiding flushing
niacinamide still may raise liver enzymes but no flush and no chol effect
EFFECTS
reduces heart attacks 27%
reduced cerebrovascular events 26%
reduced death rates 10%

PANTOTHENIC ACID = B5
also lowers cholesterol
he's surprised its not used more
mostly associated with coenzyme A
also part of another particle component: acyl-carrier protein
pantothenic means everywhere: it's in just about all foods
non-toxic, no UL set
deficiency very rare
Pantethine = B5 co-enzyme yeast free, cardiovascular research LTD
Pantethine is partially activated, special form lowers chol and TG's without toxicity
he likes this supplement

B6 = PYRIDOXINE AND MORE
very busy vitamin, 100 uses as coenzyme
many clinical uses
forms: pyridoxine, pyridoxal & pyridoxamine, pyridoxal 5 phosphate, pyridoxamine-5-phosphate
pyridoxine stable and used in supplements
all forms interchangeable, interconverted in body
synthesis of non-essential aa's
homocysteine catabolism picture page 13 in notes
neurotransmitter synthesis and myelin formation
carpal tunnel syndrome!!
depression!! cognitive problems, memory
heme synthesis, rare anemias
nucleic acid synthesis
link to role in immune dysfx
CAN BLOCK STEROID RECEPTORS
role in hormone disorders, PMS, morning sickness
neuro sx
oral cavity lesions sim to other B vits and iron def
mild def 10-25% in west, most in elderly
mb assoc with cognitive decline in elderly
impaired immune fx esp in elderly
marginal intake linked with: CV dz, immune impairment, cognitive decline, kidney stones
relative deficiency: greatly increased B6 requirements dt genetic or other disorders
RDA has been questioned: could be 2x current recommendation
many common foods are good sources but plant sources may have low bioavailability
B6 NOT in enriched grains
he says worry about this one, many people don't get enough
BOOK: Vitamin B6 therapy: John M Ellis MD and Jean Pamplin
lowers homocystiene levels
can experience SENSORY NEUROPATHY FROM TAKING SUPPLEMENTS IN 100'S OF MG OR MORE
UL SET AT 100MG BASED ON PREVENTING SENSORY NEUROPATHY
probably safe up to 200 mg/day
probably don't need long term, use temporarily
large amounts may suppress lactation
def may depress ALT and GGT

BIOTIN = no number
--> chiefly for carboxylase enzyme
used to be boring but now not so much anymore
one carboxylation rxn known for a long time
carboxylation happens everywhere all the time
one kind of enzyme, energy metab, aa metab, synthesis and oxidation of fatty acids
NEWS
required for proper fx of DNA histones
may be important for gene reg and stability
severe deficiency rare
can be caused by consuming large amounts of raw egg white
egg white contains avidin which binds biotin
avidin denatured by cooking
other def
mild deficiency may occur in pregnancy
linked with birth defects in animal research
AI for adults: 30mcg/day (1998)
large discrepancy between this and DV based on older estimates
10% of DV is acceptable (DV is 10x higher than baseline needs as far as is known)
common practice of including high DV's of B vits has never been scientifically justified
another megadose effect:
promising for DM tx: 2mg dose combined with chromium picolinate
helps stabilize blood sugar
Vitamin Research Products
no known toxicity