Vitamin E in some oils bad for lung function: Study

Are you on canola or soybean oil? Read this carefully.

According to a large study by Northwestern University's Feinberg School of Medicine, supposedly healthy vitamin E-rich oils - canola, soybean and corn - may lead to lung inflammation and, possibly, asthma.

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 - a better lung function.

"This is the first study to show gamma-tocopherol is associated with worse lung function," said senior author Joan Cook-Mills, an associate professor of medicine in allergy/immunology at Northwestern University.

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.

"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 claimed.

When people consume alpha-tocopherol, which is rich in olive oil and sunflower oil, their lung function is better, he added.

The study examined 4,526 individuals from the Coronary Artery Risk Development in Young Adults Study (CARDIA).

Cook-Mills examined the CARDIA results for individuals' lung function tests at four intervals from baseline to 20 years.

She found that a high level of gamma-tocopherol was associated with a 10 to 17 percent reduction in lung function.

"The blood plasma showed how much they had acquired in their tissues," Cook-Mills said. "You get vitamin E from your diet or supplements."

"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 maintained.

The study has been published in the journal Respiratory Research.