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The good news! Vitamin E in olive and sunflower oils improves lungs
A large new Northwestern Medicine® study upends our
understanding of vitamin E and ties the increasing consumption of supposedly
healthy vitamin E-rich oils -- canola, soybean and corn – to the rising
incidence of lung inflammation and, possibly, asthma.
The new study shows drastically different health effects of
vitamin E depending on its form. The form of Vitamin E called gamma-tocopherol
in the ubiquitous soybean, corn and canola oils is associated with decreased
lung function in humans, the study reports. The other form of Vitamin E, alpha-tocopherol,
which is found in olive and sunflower oils, does the opposite. It associated
with better lung function.
“Considering the rate of affected people we found in this
study, there could be 4.5 million individuals in the U.S. with reduced lung
function as a result of their high gamma-tocopherol consumption,” said senior
author Joan Cook-Mills, an associate professor of medicine in
allergy/immunology at Northwestern University Feinberg School of Medicine.
This is the first study to show gamma-tocopherol is
associated with worse lung function.
Cook-Mills presented her research in May at the Oxidants and
Antioxidants in Biology World Congress. It was also published in the journal
Respiratory Research.
Rates of asthma in the U.S. have been climbing in the last
40 years, coinciding with a switch in U.S. diets from lard and butter to
soybean, canola and corn oils, which were thought to be healthier for the
heart. Looking at other countries’ rates of asthma, Cook-Mills said those with
significantly lower rates of asthma have diets high in olive and sunflower
oils.
In the U.S., asthma prevalence (the percentage of people who
have been diagnosed with asthma and still have asthma) was 8.4 percent in 2010,
as reported by the U.S. Department of Health and Human Services Centers for
Disease Control and Prevention.
In the U.S., the average blood plasma level of gamma-tocopherol
is four or more times higher than those of European and Scandinavian countries
that consume sunflower and olive oil, Cook-Mills noted.
“People in countries that consume olive and sunflower oil
have the lowest rate of asthma and those that consume soybean, corn and canola
oil have the highest rate of asthma,” Cook-Mills said. “When people consume
alpha-tocopherol, which is rich in olive oil and sunflower oil, their lung
function is better.”
The study examined 4,526 individuals from the Coronary Artery
Risk Development in Young Adults Study (CARDIA). Cook-Mills had done previous
allergy research in mice showing alpha-tocopherol decreased lung inflammation,
protecting healthy lung function and gamma-tocopherol increased lung
inflammation and airway hyperresponsiveness, a characteristic of asthma. She
hypothesized that they might have similar effects in humans.
Cook-Mills examined the CARDIA results for individuals’ lung
function tests at four intervals from baseline to 20 years and the type of
tocopherol levels in their blood plasma at three intervals from baseline to 15
years. She found that a high level of gamma-tocoperol, 10 micromolar in the
blood plasma, was associated with a 10 to 17 percent reduction in lung
function. Micromolar is a measure of the amount of gamma-tocopherol per liter
volume of blood plasma.
“The blood plasma showed how much they had acquired in their
tissues,” Cook-Mills said. “You get vitamin E from your diet or supplements.”
In 2012 research, she identified a mechanism for gamma-tocopherol
increasing lung inflammation: protein kinase C-alpha, which binds both forms of
vitamin E. Alpha-tocopherol inhibits the action of the protein and
gamma-tocopherol increases the action of the protein.
“A 10 percent reduction in lung function is like an
asthmatic condition,” Cook-Mills said. “People have more trouble breathing.
They take in less air, and it’s harder to expel. Their lungs have reduced
capacity.”
People with asthma already have lower lung function, so if
they have high gamma-tocopherol levels, they would have even more difficulty
breathing, Cook-Mills said. The
individuals in CARDIA with asthma and high gamma-tocopherol had the lowest lung
function.
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