A daily dose of vitamin E may help delay the onset of type 2
diabetes in overweight adults at high risk of the disease, according to
preliminary research. Researchers in New Zealand found that high-dose
vitamin E appeared to temporarily improve insulin resistance - a
precursor to type 2 diabetes - among adults, who were overweight.
The improvement was short-lived, but another diabetes risk factor,
namely elevations in a liver enzyme called alanine transferase, changed
for the better throughout the six-month study. "These results suggest
that vitamin E could have a role to play in delaying the onset of
diabetes in at-risk individuals," said Dr. Patrick Manning and
colleagues from the University of Otago in Dunedin in the journal Diabetes Care.
This research supported the conclusions of recent studies, which
found that people whose diets had a healthy dose of antioxidants,
including vitamin E, had a lower diabetes risk than those with lower
antioxidant intakes. Vitamin E has also been shown to help some
diabetics gain better control over their blood sugar.
The new study included 80 overweight adults ages 31 to 65.
Overweight and obese individuals have an increased risk of developing
insulin resistance, in which the body loses sensitivity to the hormone
insulin, causing blood sugar levels to soar.
According to Manning's team, excess fat may speed up the
production of oxygen free radicals, the potentially cell-damaging
byproducts of normal metabolism. Moreover, overweight people tend to
have low levels of antioxidants, which counter the effects of free
radicals. It is thought that the resulting oxidative stress may
contribute to insulin resistance.
To see whether vitamin E can alter oxidative stress and insulin
resistance, Manning and his colleagues assigned participants to take
either vitamin E or a placebo pill every day for six months. For the
first three months, the treatment group took 800 IU of vitamin E each
day, followed by 1,200 IU per day for the next three months – a much
higher dosage than the recommended dietary allowance of 22 IU.
The researchers found that after both three- and six-months,
plasma peroxides, markers of oxidative stress, had fallen in the
vitamin E group. After three months, blood sugar levels and insulin
sensitivity had also improved, though the gains did not continue.
However, there was a lasting decline in blood levels of alanine
transferase liver enzymes, elevations of which have been linked to a
heightened diabetes risk. The researchers noted that the liver plays a
key role in sugar and insulin metabolism, and is the main site of
insulin clearance from the blood.
According to Manning's team, vitamin E may boost insulin
sensitivity and decrease diabetes risk in a number of ways, including
by reducing oxidative stress to cells and by improving liver function.
However, they emphasized that it is unclear why blood sugar levels and
insulin resistance improved only temporarily, when markers of oxidative
stress and liver function continued to look better. They concluded that
a larger study is needed to clarify the picture.
