Eating four or more servings of cured and processed meats, such as ham, sausages or salami, per week could worsen asthma symptoms, a new study has warned.
Cured and processed meat is rich in nitrites, which may have a role in airway inflammation - a typical feature of asthma.
To find out if dietary processed meat intake was associated with the worsening of asthma symptoms over time, and what role, if any, obesity might have, researchers drew on data from participants in the French Epidemiological study on the Genetics and Environment of Asthma (EGEA).
The study by researchers, including those from Inserm, French National Institute of Health and Medical Research, is based on 971 adults (49 per cent men) for whom complete dietary, weight (BMI), asthma symptom score and demographic data were obtained up to 2011-13.
Dietary intake was measured using food frequency questionnaires encompassing 118 items in 46 food groups.
Cured meat intake - ham, sausage, salami - was classified as low for one or fewer weekly servings; medium for one-four weekly servings; and high for four or more.
Asthma symptoms, such as difficulty breathing, chest tightness, and shortness of breath in the preceding 12 months, were scored from zero to five (asthma symptom score).
Information was also gathered on other potentially influential factors, such as smoking, regular physical activity, age, sex, and educational attainment.
Between 2003 and 2007, 42 per cent of the participants said they had had asthma at some point, and around half (51 per cent) had never smoked.
Just over a third (35 per cent) were overweight, while nearly one in 10 (9 per cent) were obese.
Participants said they ate an average of 2.5 servings of cured/processed meat intake a week.
By 2011-13, when the next checks were made, there had been no change in asthma symptom score for just over half the participants (53 per cent; 513).
In one in five (20 per cent) symptoms had worsened and in around one in four (27 per cent) symptoms had improved.
Among those who ate one or fewer weekly servings, the proportion of those with worsening asthma symptoms was 14 per cent; among those eating one-four, the proportion was 20 per cent; and among those eating four or more, the proportion was 22 per cent.
After taking account of potentially influential factors, such as smoking, regular physical activity, age, sex, and educational attainment, those who ate the most cured meats were 76 per cent more likely to experience worsening asthma symptoms than those who ate the least.
Overweight/obesity, which has previously been linked to worsening asthma, accounted for just 14 per cent of this association, the calculations showed, suggesting that processed meat intake may have an independent role in asthma symptoms, the researchers said.
The study was published in the journal Thorax.