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A Fatty Meal Can Increase Lung Inflammation in Asthmatic Patients


The prevalence of asthma has increased significantly over the past few decades. One factor implicated is the increase in obesity and the typically high-fat Western diet. Most people think that a high fat diet only affects health over a long period of time. However, Australian researchers have found that one high fat meal can increase inflammation and reduce lung function immediately in people with asthma.

For the study, Lisa Wood PhD, a research fellow at the University of Newcastle in Australia, and colleagues recruited thirty non-obese people and 16 obese patients with asthma. The non-obese volunteers were randomly selected to receive either a high-fat meal or a low-fat meal. All of the obese participants received a high fat meal.

The 1000-calorie high-fat meal consisted of fast-food hamburgers and hash browns, contributing about 50% of calories from fat. For reference, the American Heart Association recommends no more than 25-35% of calories come from fat. The low-fat meal was 200 calories and 13% fat, consisting of a low-fat yogurt.
Sputum samples and lung function were tested at the start of the study and four hours after the meal.

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The researchers found that markers of airway inflammation, called neutrophils, increased significantly while lung function was reduced among those who ate the high-fat meal. The volunteers who used an asthma inhaler containing albuterol after the high-fat meal had an impaired response to their medication.

Dietary fat, particularly saturated fat, can activate an immune response in the TLR4 mRNA gene and cause an inflammatory reaction in other parts of the body, but this is the first study that has looked at the effects of a high-fat challenge on inflammation within the airways.

Dr. Wood and her team plan further research but suggest that methods to reduce dietary fat intake may be useful in the management of asthma. "Further work is needed to understand the clinical relevance of these observations. Nonetheless, a difference of 3 to 4 percent [in lung function] is approaching a level which can be perceived by patients," said Dr. Wood.

She also said that they do not yet know how long these effects might last, but that if someone is consuming high-fat foods every day, they may be experiencing inflammation for at least several hours a day.

The research was presented today at the American Thoracic Society’s International Conference in New Orleans.



The first question that springs to mind without having seen the study is, were the hash browns cooked in artificial trans fats? Trans-fatty acids are well-documented to increase inflammation which is the main reason why they are being pressured off the market. At the same time, there is a commercial incentive to denigrating fats in general in the diet as opposed to carbohydrates as the later have a much longer shelf life and don't go rancid. Indeed, one of the main benefits, commercially speaking, of trans-fats, aside from being cheap is their longer shelf life. Not that one can't have an unhealthy overly fatty diet, but simply that I would have to question whether the asthma effect being documented here relates to the consumption of artificial trans-fats versus yogurt as opposed to the consumption of a high fat meal versus yogurt. There is a good discussion and introduction to trans-fats here, http://healthjournalclub.blogspot.com/2010/03/100-year-diet-revisited-trans-fats.html if anyone might be interested.