According to a recent study, individuals with asthma who consume relatively high amounts of cured meats, such as ham, sausage, and salami, are more likely to experience worsening symptoms.
Cured meats are the latest dietary pariah - and for good reason. Over recent years, studies have racked up a fearsome list of their deleterious effects on health and longevity.
In fact, the World Health Organization (WHO) recently declared them carcinogenic.
Not only do cured meats increase cancer risk, they also raise the risk of coronary heart disease and type 2 diabetes.
As far as lung health is concerned, the grim theme continues. Increased consumption of salami and other such meats has been tied to lung cancer, decreased lung function, and increased symptoms and incidence of chronic obstructive pulmonary disease (COPD).
A recent study, published in the journal Thorax, set out to identify whether cured meat consumption also had a negative impact on asthma. To date, only two studies have specifically looked at this interaction, and both of them found no effect.
The group reopened the investigation into asthma and cured meats, as well as set out to understand the role of obesity in worsening asthma symptoms.
Why would cured meats damage the lungs?
Researchers believe that there are at least two pathways by which cured meats damage tissues in the body. Firstly, they are high in nitrites, which can lead to nitrosative stress and oxidative stress, both of which damage cells.
Secondly, there is a relationship between consuming cured meats and increased levels of C-reactive protein, a key player in the immune system. C-reactive protein can induce inflammation, resulting in tissue damage over time.
Taking data from the French Epidemiological study on the Genetics and Environment of Asthma (EGEA), 971 adult participants were used. The EGEA has tracked asthma patients using questionnaires and medical examinations for more than 20 years.
Data on diet, weight, and asthma symptoms were collected. Demographic information and other lifestyle factors were also collated, such as level of exercise, smoking, sex, age, and educational attainment.
On average, participants ate 2.5 servings of cured meat per week. Those who ate one or less per week were classified as low consumers, people consuming one to four weekly servings were classified as medium, and they were classified as high if they consumed more than four.
The initial data was collected between 2003 and 2007, and a follow-up was carried out between 2011 and 2013.
Overall, asthma had worsened in 20 percent of the group, improved in 27 percent, and seen no change in the remaining 53 percent.
Cured meat and asthma
When cured meat intake was examined, the researchers found that 14 percent of low consumers, 20 percent of medium consumers, and 22 percent of high consumers had worsening symptoms.
Once other factors were controlled - smoking, regular physical activity, age, sex, and educational attainment - those who ate the most cured meats were 76 percent more likely to have experienced worsening asthma symptoms than those who ate the lowest amount of cured meats.
The team was also interested in gaining a deeper understanding of the role that obesity plays in asthma. Being overweight has previously been linked to worse asthma symptoms, but in the present study, body mass index (BMI) accounted for only 14 percent of worsening symptoms. This suggests that the consumption of cured meats has an independent influence on asthma, above and beyond weight.
It is important to note that this is an observational study, and conclusions regarding cause and effect cannot be drawn. Also, as the authors point out, the results were reliant on participants' memories. Additionally, symptom scores could have been affected by smoking or by COPD, which shares many symptoms with asthma.
That being said, other previous research has shown links between processed meats and lung health, so the current work adds to the weight of evidence.