Nutrition: Vitamin E

[liveonearth]

VITAMIN E
more like a carotenoid
fat soluble
best supplement? mixture? balance like nature?
mixes tend to be mostly alpha tocopherol
store in cool and dark
destroyed by cooking
sources: vegetable oils, nuts, whole grains, green leafy veggies, fortified foods

8 forms, called vitamers
four tocopherol (alpha, beta, delta, gamma)
four tocotrienols (alpha, beta, delta, gamma)
synthesize any one of those get eight versions of it (RRR etc)
natural vit E: is d- or RRR
synthetic: dl- or all-rac = RRR plus seven other stereoisomers
natural works better
dl-alpha means natural source
dl- means synthetic
RRR means all bonds are in natural configuration
see also SRR, SSR, SRS, SSS, RSR, RRS, RSS

esterification increases shelf life
tocopheryl acetate
tocopheryl succinate
not as good because esters have to be broken off before it's biologically active

why do we only hear about alpha tocopherol these days?
it is most abundant in body tissues
most vit E from diet-->chylomicron-->liver-->VLDL-->LDL-->tissues
selectivity of hepatic alpha tocopherol transfer protein:
directs incorporation of alpha vitamer into VLDL
gamma is most abundant in diet, 2nd most researched
gamma present in intestine, liver, certain cells

SUPPLEMENTS
want a good mix: hard to find
Linus Pauling Institute says take 200 IU/day natural vitamin E
Harvard doesn't make a recommendation
some recommend 20% or more gamma content, some say 50/50 alpha and gamma
nobody knows how much of the others is optimal

ALPHA TOCOPHEROL
antiox in lipid environments (membranes, LDL particles)
gene and cell regulation
immune fx
inflam
vascular health

GAMMA TOCOPHEROL
may contribute anti-ox, anti-inflam and other fx
active research area

TOCOTRIENOLS
may affect chol reg and have neuroprotective effects

DEFICIENCY
rare, causes lipid transport problems
Sx: neurological, RBC's hemolyze
suboptimal intake is common based on blood levels consistent with CV risk
RDA = 15mg or 22.5 IU of alpha tocopherol
average intake is only 9mg males 6 females

SCIENCE: COST/BENEFIT
supplements up to 100mg/day show less heart disease from observational study
intervention studies of chronic dz inconsistent/disappointing
most frail patients have been harmed not helped by vit E
healthy subjects get benefit
cancer debate: no clear advantage, variable results on prostate
hopeful for Alzheimer's tx

SAFETY
antiplatelet effects
UL is 1000mg/day 1500IU/day
stop before elective surgery
do not recommend vit E to frail pts with chronic dz based on current research