According to a new sizable study by Northwestern Medicine, vitamin E-rich oils - including canola, soybean and corn - could be contributing to the rising incidence of lung inflammation, airway hyperresponsiveness and possibly asthma. In contrast, vitamin E-rich oils such as olive oil, wheat germ oil, almond and sunflower oil improve lung capacity and function.
The research furthers our understanding of two of the four tocopherol forms of vitamin E - gamma-tocopherol and alpha-tocopherol - and their health advantages and disadvantages.
Vitamin E exists as an antioxidant that protects the body from free radicals that can harm cells, tissues and organs. Vitamin E maintains the immune system, to discourage viruses and bacteria. It is also significant in the formation of red blood cells and helps the body utilize vitamin K.
The National Institutes of Health say the best way to achieve the Recommended Dietary Allowance (RDA) of vitamin E is by eating vitamin E-rich food sources, such as vegetable oils, nuts, seeds and green leafy vegetables.
Gamma-tocopherol is the most common form of vitamin E found in the American diet, due to high intakes of canola, soybean and corn oil.
Vitamin E-rich oils including canola, soybean and corn could be contributing to the rising incidence of lung inflammation.
Olive oil, wheat germ oil, almond and sunflower oil are all sources of alpha-tocopherol that have a higher dietary intake in European and Scandinavian countries.
The average blood plasma level of gamma-tocopherol is four or more times higher in the US than that of countries that consume olive and sunflower oil.
This study is reportedly the first to link gamma-tocopherol with diminished lung function and poses us to question, how good are "healthy oils" for our health?
The researchers analyzed the dataset from Coronary Artery Risk Development in Young Adults Study (CARDIA), which was sponsored by The National Heart, Lung and Blood Institute of the National Institutes of Health. CARDIA is a population-based observational study with 5,115 participants aged 18-30 recruited between 1985 and 1986.
The findings allow increased understanding of the development of heart disease in black and white adults. The same number of people in subgroups of race, gender, education and age were selected with follow-up examinations during years 2, 3, 7, 10, 15 and 20 after the initial examination.
Of the 5,115 individuals who took part in the CARDIA study, data was excluded for participants with COPD and without data for tocopherol levels, spirometry, BMI, height or smoking, leaving 4,526 people.
Senior author of the study Joan Cook-Mills analyzed spirometry data to measure lung function and capacity in years 0, 2, 5, 10 and 20, and tocopherol type levels present in the participants' blood, in years 0, 7 and 15.
"The blood plasma showed how much they had acquired in their tissues." Cook-Mills says. "You get vitamin E from your diet or supplements."
High gamma-tocopherol levels associated with a 10-17% reduction in lung function
Cook-Mills found that higher concentrations of gamma-tocopherol in the blood plasma indicated a 10-17% reduction in lung function.
Could the rise in asthma cases over the last 40 years correspond with our mission for a healthier lifestyle and heart, by cutting down on lard and butter and switching to "healthier" soybean, canola and corn oils?
Cook-Mills noted that those countries with lower rates of asthma have diets high in olive and sunflower oils - oils rich in the form of vitamin E, alpha-tocopherol.
Cook-Mills, an associate professor of medicine in allergy/immunology at Northwestern University Feinberg School of Medicine, says:
"Considering the rate of affected people we found in this study, there could be 4.5 million individuals in the US with reduced lung function as a result of their high gamma-tocopherol consumption."
This study is one of many studying the health benefits and detriments of vitamin E. Earlier this year, Medical News Today reported on findings that antioxidants may speed up lung cancer progression in the form of vitamin E and acetylcysteine.