A high intake of cured meat (at least 4 times a week) is associated with an aggravation of asthma symptoms over time. These results, published in the journal Thorax by a team of Inserm researchers (Inserm Unit 1168, “Aging and chronic diseases: epidemiological and public health approaches”) were obtained from data collected from 1,000 individuals monitored for an average of 7 years.
Eating cured meat – recently classified as carcinogenic by WHO – has already been associated with an increased risk of chronic obstructive pulmonary disease (COPD), but its association with asthma had never been demonstrated. A growing body of evidence, which includes the fact that a change in dietary habits or an increase in obesity over time is implicated in asthma, led the researchers at Inserm to examine this question more closely.
An analysis was conducted, using data from the EGEA study, on nearly 1,000 participants monitored for seven years. People included in the cohort had a mean age of 43 years. During the period, 20% reported an aggravation of their asthma symptoms. In order to understand the reasons, the Inserm researchers focused on their diet.
It was first necessary to eliminate the “obesity” parameter, which could have distorted the results. Since BMI is a risk factor that has already been identified in the occurrence of asthma, it was indeed plausible that it represents a causal mediator between the effects of diet that the researchers wished to examine (namely cured meat intake) and asthma. The scientists therefore took this parameter into account to adjust their results, using a recent epidemiological method known as MSM (marginal structural models).
And only 14% of the association between cured meat intake and asthma was explained by obesity (indirect effect).
“These new results show a greater direct effect of diet on asthma in adults. In order to protect the respiratory health of the population, public health messages aimed at limiting cured meat intake should be quickly introduced,” explains Zhen Li, main co-author of this work.
 An epidemiological study of the genetic and environmental factors associated with asthma, bronchial hyperactivity and atopy.
 This method allows for a causal route in which a confounding factor exists in order to measure the direct effect of a factor A on another factor B (see Figure 2 of the scientific article)
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