Joan M. Cook-Mills, PhD, professor of medicine, department of allergy/immunology, Feinberg School of Medicine, Northwestern University, Chicago. Her study was published in Respiratory Research.
I’m sure you’ve been keeping up with the “good cooking oil/bad cooking oil” health updates. Remember when we were all told to opt for “vegetable oil”—soybean oil, that is—instead of corn oil? Since then, we’ve learned that soybean oil and other vegetable oils such as corn and canola aren’t “all that.” In fact, there’s new research showing that favoring certain cooking oils over others may promote lung inflammation that can get in the way of how well we breathe and feel and even influence development of lung diseases such as asthma. It comes down to nuances about vitamin E, an antioxidant nutrient that is in both vegetable and olive oils.
You see, many plant oils are rich in vitamin E—but the term vitamin E is actually a catchall for eight different chemical compounds, each with its own antioxidant profile. And the problem is that we may be getting way too much of one certain type of vitamin E that’s not good for us.
We know from animal experiments that a type of vitamin E called D-alpha tocopherol and another type called D-gamma tocopherol have completely opposite effects on lung function…one good, the other bad. Never mind animals…what about the effects in you and me? A team of researchers from the Feinberg School of Medicine at Northwestern University in Chicago and other universities compared blood levels of vitamin E against the results of lung-function tests (which measure how much air a person can exhale in one big breath) of more than 4,500 people. And the researchers confirmed that these two different vitamin Es—D-alpha tocopherol and D-gamma tocopherol—have the different effects…
• D-gamma tocopherol was associated with worse lung function for everyone, and the higher the level, the worse the lung function.
• D-alpha tocopherol, on the other hand, was associated with better lung function for everyone. The study also showed that increases in D-alpha tocopherol could counteract the effects of D-gamma tocopherol.
What’s behind this? It seems that D-alpha tocopherol inhibits allergic inflammation—that is, inflammation that is set off by allergies—while D-gamma tocopherol promotes allergic inflammation. Sometimes your body wants and needs temporary inflammation, for example, to help isolate causes of tissue injury, such as bacteria and toxins. But a steady diet (literally!) of a substance that enhances inflammation—even if it is a vitamin—is going to hurt you. Another recent study found that too much D-gamma tocopherol in the body can aggravate osteoarthritis—so its effects aren’t limited to the lungs but, in all likelihood, extend anywhere that inflammation can develop.
You are what you eat, they say, and it’s becoming clearer that Europeans, for example, may breathe easier than Americans in part because they have two to six times less D-gamma tocopherol in their bodies than American adults do—and the main reason is that Europeans use more olive oil or safflower oil, which are low in D-gamma tocopherol and high in D-alpha tocopherol. Americans, on the other hand, consume more soy, corn and canola oils, which are very high in D-gamma tocopherol..
So, even if you never get asthma or another disease that compromises your ability to breathe, the evidence suggests that you can help your lungs be healthier and stronger and naturally breathe better by making some very simple food choices.
Cooking oils that are richer in D-alpha than D-gamma tocopherol include olive, sunflower and safflower, which can replace soy, corn and canola oils. Sunflower seeds, hazelnuts, almonds and wheat germ are also rich in D-alpha tocopherol. What about vitamin E supplements? Some contain only D-alpha tocopherol, some only D-gamma tocopherol, and some a mixture of the two types. If you want to take a supplement, consult with a doctor specifically trained in nutrition (a naturopathic doctor or a chiropractic doctor)—or better yet, a nutrition specialist (registered dietician).