Eating processed meats such as ham and salami more than four servings a week could be bad for asthma, according to a French study released Tuesday.

The researchers studied 971 people who took part in the Epidemiological Study on the Genetics and Environment of Asthma. These participants, all of whom have experienced some degree of asthma, were asked to fill out questionnaires regarding their symptoms as well as food frequency questionnaires.

The participants were asked about consumption of processed meats, such as ham, dried sausage and salami. Consumption was classified as low for one or fewer servings a week, medium for one to four servings, and high for four or more.

After collecting and analyzing the data, the researchers found that those who ate the most processed and cured meats were 76 percent more likely to witness worsening asthma symptoms compared to those who ate the least.

The symptoms include trouble breathing, chest tightness and shortness of breath, the study said.

A preservative called nitrite, which is often used to keep processed meats from spoiling, is believed to be the culprit, as it aggravates the airways.

But experts say the theory has not been proven and more investigations are needed.

Last year, the World Health Organization announced that processed meats like bacon and hot dogs may lead to a higher risk of other chronic diseases like cancer and heart disease.

Instead of worrying about one type of food, people should have a healthy and varied diet, researchers said.

The study, published online in one of the world's leading respiratory medicine journals Thorax, was led by Zhen Li, a Chinese PhD student at the French National Institute of Health and Medical Research.

source: Xinhua