Do Cured Meats Worsen Asthma Symptoms?
The few scientific studies that have investigated a potential link between cured meats (including sausage, salami, and ham) and asthma have not found any relationship. A new study published in the academic journal Thorax, however, claims to have identified a negative impact of cured meats on asthma symptoms. These results are consistent with some other research projects that have found that processed meats adversely affect the health of the lungs. Indeed, cured meats have been linked to a number of health problems, including heart disease, diabetes, and cancer.
The study analyzed adult asthma patients, based on their diet, their asthma symptoms, and their weight. Researchers first collected information on the patients between 2003 and 2007 and then followed-up to see how their asthma symptoms had changed between 2011 and 2013. The scientists found that each week, the average patient consumed 2.5 servings of cured meat. Researchers divvied the patients up into three groups for their analysis: low consumers (who ate one or fewer servings of cured meat per week), medium consumers (who ate one to four servings of cured meat each week), and high consumers (who ate more than four servings of cured meat each week).
During their follow-up, scientists found that more than half the patients (53%) had not experienced a change in their asthma symptoms. However, 20% of the patients had experienced worsening symptoms, whereas 27% had experienced improved symptoms. When analyzing the data from the perspective of cured meat consumption, the researchers found that of those patients with worsening asthma symptoms, 22% were high consumers. By contrast, only 20% of those with worsening symptoms were medium consumers - and an even smaller percentage (14%) were low consumers.
Body mass index (BMI) has been shown to be associated with asthma symptoms, with overweight individuals tending to have more severe asthma symptoms than others. It has therefore questioned whether the potential link between consuming cured meats and experiencing worsening asthma symptoms could simply be a reflection of higher BMI in these groups. However, upon closer inspection of their data, the researchers found that BMI only accounted for 14% of the worsening asthma symptoms in those eating cured meats. The study also controlled for other factors, including age, sex, education, exercise routine, and smoking habits, but because the study was observational, it is not clear if the apparent relationship between cured meats and asthma symptoms indicates that eating high levels of cured meat actually causes worsening asthma symptoms.
Scientists have pondered what might make cured meats worsen asthma symptoms if the relationship is actually causal. Most of their ideas point to ways in which cured meats may cause damage to the lung tissues over time. For instance, the high levels of nitrates that are present in cured meats can cause the oxidative stress that is strongly linked to tissue damage. Cured meat consumption is also associated with enhanced levels of C-reactive protein, which has a role in the immune system. Specifically, C-reactive protein can lead to inflammation, a well-known cause of tissue damage. Now that a link between cured meat consumption and worsening asthma symptoms has been demonstrated in one study, further research is likely to follow that will enhance our understanding of this potential link and any reasons it may exist.