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High cured meat intake tied to worsening asthma symptoms

High dietary intake of cured meat was associated with worsening asthma symptoms over time, and this effect was slightly mediated by increase in body mass index (BMI), according to data from the EGEA* study.

“Cured meats are rich in nitrite, which may lead to nitrosative stress- and oxidative stress-related lung damage and asthma,” said the researchers.

After a mean follow-up period of 7 years, 20 percent of the participants reported that their asthma symptoms had worsened compared with baseline (change in asthma symptom score >0). Fifty-three percent of them reported no change in asthma symptoms, while 27 percent had improved symptoms. [Thorax 2016;doi:10.1136/thoraxjnl-2016-208375]

More participants reported worsening asthma symptoms over time with increasing weekly intake of cured meat, ie, 14, 20 and 22 percent for those who ate <1, 1–3.9 and ≥4 servings/week of cured meat, respectively (p for trend=0.04).

Participants with the highest weekly consumption of cured meat, ie, ≥4 servings/week, were 76 percent more likely to experience worsening asthma symptoms than those with the lowest intake of <1 serving/week (odds ratio [OR], 1.76, 95 percent confidence interval [CI], 1.01–3.06).

The researchers also found that those with the highest intake were more likely to be male (p<0.001), younger (p<0.001), smokers (p=0.04), asthmatic (p=0.03), and to have a higher BMI (p=0.01). Nonetheless, the association between cured meat consumption and worsening asthma symptoms remained even after adjusting for sex, age, educational level, smoking history, and physical activity.

Testing the effects of BMI on asthma symptoms using marginal structural model revealed that BMI had indirect effects on asthma symptoms, mediating 14 percent of the total effects cured meat consumption had on asthma symptoms (OR, 1.07, 95 percent CI, 1.01–1.14).

“The indirect effect mediated through BMI accounted for only 14 percent of the total effect, supporting the hypothesis that the cured meat-asthma association is related to other mechanisms,” said the researchers.

The prospective longitudinal French study analysed 971 participants (mean age 43 years, 42 percent with asthma) who had completed self-administered questionnaires on food frequency and asthma symptoms. Asthma symptom score was based on five symptoms: breathless while wheezing, waking up with chest tightness, waking up due to shortness of breath, shortness of breath at rest and after exercise.

As other food groups/nutrients consumed as part of a complex meal may interact with each other, this may confound the findings, according to the researchers, who also acknowledged that the results may not be applicable to populations with very different diet habits.

In addition to the nitrite content, the researchers suggested that C-reactive protein, which has been associated with cured meat intake, might increase systemic inflammation leading to asthma.

*EGEA: Epidemiological Study on the Genetics and Environment of Asthma


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