Worldwide, government organizations are not quite in
agreement on how much is recommended and what is the safe upper limit. The U.S.
recommends 15 mg/day, and up to 1000 mg/day as safe. Japan recommends 7 mg/day
and no more than 900 mg/day (for men, numbers a bit lower for women). The
European Union recommends 11 mg/day for women, 13 mg/day for men, and no more
than 300 mg/day for both sexes. Actual consumption is less. Worldwide, median
dietary intake is 6.2 mg/day for alpha-tocopherol.
The popularity of naturally sourced or synthetic alpha-tocopherol
as a dietary supplement began with a juxtaposition of theory and observation.
Vitamin E is thought to function as an antioxidant. Oxidation is all about oxygen
(duh!). Normal biological processes create oxidating compounds, also referred
to as free radicals, that need to be neutralized, else cell damage takes place.
One of the theories of aging is that oxidation causes cumulative damage over
years and years, leading to what we identify as the diseases of aging. Our
bodies create antioxidants and also use vitamin E (and vitamin C, and selenium)
as antioxidants. These nutrients, alone and in combination, have been heavily
researched for disease prevention. With mixed results.
Observational studies tracked the lifestyle habits and
health histories of tens of thousands of nurses and doctors. Results showed
that those who on their own either consumed more vitamin E because of food
choices, or had chosen to take vitamin E dietary supplements, had a one-third
lower risk of heart disease. Publicity from this let to roughly 50% of nurses
and doctors to use vitamin E as a dietary supplement. Millions of Americans
followed the examples of their health care professionals. Sadly, subsequent
clinical trials that enrolled people to either vitamin E or a placebo and
tracked them for years were not as consistently positive. Collectively, there
appears to be a modest reduced risk for heart attack, no benefit for risk of
stroke, and no change in all-cause mortality. With hindsight, in the initial
research, health professionals who had decided to consume vitamin E supplements
may have made other lifestyle decisions that promoted good health. It is an
example of correlation not necessarily reflecting causality.
Research for other diseases has also had mixed results. An
antioxidant combination appears to slow progression of age-related macular
degeneration, but vitamin E alone has not been evaluated. There has not been
enough research for any recommendation on effects on dementia, or on
Parkinson’s disease. Vitamin E in combination with vitamin C was not seen as
beneficial for pregnancy outcomes. Cancer results are mixed depending on type;
also some evidence that while low amounts of a supplement are beneficial,
higher amounts actually increase risk (a similar cross-over effect seen for
higher amounts and cardiovascular disease).
Despite the widespread belief that topical vitamin E can
help with burn and wound healing, rigorous clinical trials belie that
conclusion. There is no useful evidence supporting the idea that a vitamin E
containing shampoo or conditioner improves hair health.
Cumulatively, doubts about efficacy and concerns for subtle
negative effects of higher doses led to a massive decline in the percent of
people buying vitamin E. What to do in
the face of all this ambiguity? Eat more fruits and vegetables (always an easy recommendation).
Most daily multi-vitamin/mineral products will include 100% of the Daily Value
for vitamin E, which can be seen as do-no-harm. Beyond that, the merits for a
vitamin E as a supplement are suspect, and this is definitely not a
more-is-better situation.
The Wikipedia article on Vitamin E has references for most of this content.
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