High-fat foods may trigger airway inflammation, study finds

People with asthma are familiar with typical triggers such as exercise, allergies and smoking that can bring on inflammation. Add to that list high-fat meals, which may also increase inflammation in airways, according to a new study.

Australian researchers did tests on 40 people with asthma who were randomly assigned to eat different meals. One was a high-fat meal of fast food hamburgers and hash browns that came in at 1,000 calories, with 52% of calories from fat. The other was a 200-calorie low-fat meal of reduced fat yogurt with 13% of calories from fat. Included in the high-fat test group were 16 obese people; the rest of the study participants were not obese.

Before and after the meals, sputum samples were taken from the test subjects to be analyzed for inflammatory markers. Those who ate the high-fat meals showed a significant boost in airway neutrophils compared with those who ate the low-fat meal. Neutrophils are a common type of white blood cell found in the body's airways while an asthma attack is happening, as well as afterward. Those who ate the high-fat meal also showed an increase, compared with the low-fat group, in a gene expression that is another marker for inflammation.

Eating the high fat meal also prompted a suppressed response to albuterol, a bronchodilator that increases air to the lungs. The obese and nonobese participants in the high-fat group did not differ in their responses.

"The observation that a high-fat meal changes the asthmatic response to albuterol was unexpected as we hadn't considered the possibility that this would occur," said Lisa Wood, a research fellow at the University of Newcastle in Australia, in a news release. Wood, lead author of the study, added, "We are designing more studies to investigate this effect. We are also investigating whether drugs that modify fat metabolism could suppress the negative effects of a high fat meal in the airways. If these results can be confirmed by further research, this suggests that strategies aimed at reducing dietary fat intake may be useful in managing asthma."

The study was presented at the American Thoracic Society's international conference in New Orleans this week.

-Jeannine Stein

Photo: High-fat meals may trigger airway inflammation responses in those who have asthma. Credit: Anacleto Rapping / Los Angeles Times

Comments

[Melissa McDowell]

This comparison is invalid for several reasons:

The meals were not isocaloric (did not have the same number of calories)

One meal included wheat, a food known to promote inflammation, and one didn't.

One meal was comprised of dairy only, and dairy products are known to reduce inflammation.

The study participants were not even randomized into different groups!

In short, any number of things could have caused the results because there were too many variables.

[Dave, RN]

What? You're comparing 1000 kcal vs 200?? Maybe it's the differnce in intake? Maybe it's the carbs and starches (hamburger buns and potatoes) that came with the high kcal diet. Or maybe it was the 16 obese people in the highfat test group that were not in the other group. This wouldn't pass for a Jr. High science project.
Science FAIL!

[ivy]

Who does these 'studies'? I saw better designed studies than this at our elementary school science fair.

[Paul Bowers]

Hmmmm, a 200-kcal meal vs. a 1000-kcal meal? if 52% of the calories in the "high fat" meal came from fat, that means approximately 30% or 300 kcal came from carbohydrate (assuming 20% protein). couldn't this be telling us that carbohydrate, fat, protein or just plain calories in general is the trigger? gotta love how fat gets blamed for everything...

btw, i'm a life-long asthma sufferer. since switching to a low-carb, high-fat diet (~80% of calories from fat) to address my metabolic issues, my asthma has all but been cured. no more seasonal allergies, and haven't had an attack since the change. could be concidence, but certainly pokes a big hole in the "fat is a trigger" hypothesis, huh?

[Eric Rosenstock]

Junk science yet again. Bravo. Exact opposite results to what I witness every day in my own clients and the clients of others who promote a paleo / low processed carb diet. I had a better understanding of how to conduct a proper experiment with multiple variables in 6th grade.

[Jennifer Harmon]

In addition to wheat, the fast food meal was probably high in omega-6 polyunsaturated fatty acids, also known to promote inflamation.

If you're a researcher concerned that fat might worsen asthma, then you do a study that isolates the possibly quite disparate effects of n-6 PUFAs, n-3 PUFAs, saturated fats, and monounsaturated fats on inflammatory markers, and you leave out the extraneous foods such as yogurt and bread.

[Phil]

Wow, way to randomize. 16 out of the 20 in the high-fat group were obese, while 0ut of the 20 in the low-fat group were obese.

Is it news that feeding fat people a good-sized meal with plenty of wheat & vegetable oil is going to cause a worse outcome than feeding thin people a negligible amount of yogurt? Australians might actually be dumber than Americans if they take this baloney seriously.

[S. Williamson]

These articles are fantastic! Thanks for sharing this type of information with the public. We definitely appreciate the time & research that is invested in producing quality work like this. We'll be back for more.

[MB]

The only reason we can have discussions like this is because millions of years ago some primates started eating "high fat diets." Had they not, we'd still be vegetarian apes with little brains.

How is eating vegetable oil, wheat, potatoes, GMO vegetables and fast food "meat" (presumably feed lot garbage and filler) considered a "high fat" diet? That's like eating 1,200 calories of candy every day and calling it a healthy "low calorie" diet.

Eat Paleo/Primal. It's what got us here.

[Melissa]

This is either a bad study or awful reporting.
You can't say a diet that is high in fat is the problem if it also consists of hashbrowns and bread.
They also have to declare what type of fat was used for cooking- like transfats?

It's a botched study and using it against a 200 calorie low fat starvation diet?
Actually both of them are starvation levels.
It's ridiculous. They have no idea what caused those lung inflammation. Was it the bread? The vegetable fat? the startches? They have no clue.

What an awful article.

[Don Wiss]

Another useless study. The high fat meal also included bread and potatoes. How do they now that these foods weren't the cause? And the fat was at least partly trans fats. They blamed high fat because that is what is politically correct to blame. But this study doesn't tell us a thing.

[Jan]

Such an experiment could be done with pills containing 1) omega-3 fatty acids, 2) omega-6 fatty acids, 3) monounsaturated fatty acids, 4) saturated fatty acids, 5) placebo. People engaging experiment should be divided into at least two age and weight groups.