MADRID, January 31 (EUROPE PRESS) –
Researchers from Johns Hopkins Medicine (USA) have shown in a study with mice that a low-calorie diet prevents asthma symptoms, regardless of the fat and sugar content of the diet. In their studies, they also found that obesity caused by a high-calorie diet causes asthma symptoms in animals, causing pneumonia, because the medicine that blocks inflammation relieves these symptoms.
These results complement the evidence supporting the link between obesity, inflammation and asthma, as well as the value of anti-inflammatory drugs for treating the characteristic asthma symptoms associated with obesity. Obese people are much more likely than normal-weight people to develop certain types of asthma or the symptoms of this disease increase.
"Previous studies suggested that high fat or sugar in diets, which led to obesity, contributed to inflammation and asthma, but our study shows that obesity causes asthma symptoms associated with inflammation, regardless of the composition of the diet, and that calories by any means can prevent or treat asthma, reducing inflammation, ”explains the lead author of the study Vsevolod Polotsky.
In this study, published in the journal Scientific Reports, researchers fed normal male mice with one of four diets: a low-calorie diet, which is a standard laboratory diet of crunchy foods without calorie restriction; high-calorie diet that contains more calories and fat per gram; high-calorie diet that contains more fat per gram and supplemented with additional sugar; and a high-fat, high-fat diet supplemented with sugar.
In addition, individual groups of mice were given high-calorie diets, but their daily food intake was limited to match the number of calories that mice consume on a low-calorie diet.
High calorie mice gain more weight
After eight weeks, mice with any high-calorie diet that was not restricted in their diet gained at least 7 grams more than mice with a low-calorie diet or mice with a diet with a high calorie restriction.
The researchers then assessed lung function in animals to find out if asthma symptoms developed in mice by measuring the constriction of the pulmonary respiratory tract, when the mice inhaled various doses of methacholine, a drug that causes the constriction of the respiratory tract.
With a dose of 30 mg per milliliter of methacholine in mice with all types of high-calorie diets, the diet of which was not limited, the airways narrowed at least 6.3 times more than the initial value, whereas in mice with a low-calorie diet or in mice with a restriction food on a high-calorie diet airways were reduced by no more than 4.7 times more.
The results of these tests, similar to those used to identify or diagnose asthma in humans, showed that mice with a high-calorie diet developed asthma symptoms as well as obesity.
In previous studies, Polotsky and his team showed that mice fed a high-fat diet for two weeks had high levels of IL-1 B (interleukin-1 beta), a protein whose presence indicates inflammation in the body.
In their new experiments, they tried to more accurately determine the relationship between obesity, the inflammatory response and asthma, for the first time in eight weeks by feeding mice with high-fat diets. They then injected a drug called anakinra to a group of mice every day for two weeks to block the activity of the IL-B protein and, therefore, inflammation, preventing it from entering target sites. Due to its anti-inflammatory properties, anakinra is used to treat rheumatoid arthritis.
At the end of eight weeks, when they were given a dose of 30 milligrams per milliliter of methacholine to test the sensitivity of their airways, in obese mice with an anakra, the airways were narrowed 2.9 times more than the initial value, lower than the 5.1-fold increase observed in obese mice who were not given medication.