Most people would like a forewarning if they’re at a higher risk of death than other people. Some clues are obvious: If you’re ingesting healthy foods, for example, you live longer. But sometimes we can find signals in unexpected places; like clues to your mortality may be in your spit. Seriously. Researchers have discovered that a lower level of antibodies in saliva are associated with an elevated risk of dying, and could function as an early indicator of said risk.
The research, published by a team from the University of Birmingham, explored the association between an antibody commonly found in saliva (secretory immunoglobin A, or IgA), and mortality rates in the general population. They looked at 639 adults aged 63 or older at the time of saliva sampling in 1995, and measured their IgA secretion rates. The participants were then tracked for mortality over the following 19 years, with any associations being measured for gender, occupational group, smoking, and medication usage.
There ended up being a negative association between IgA secretion rate and all-cause mortality. A deeper analysis of the data showed that the all-cause association was possibly due to an underlying association with cancer mortality particularly with non-lung cancers.
Immunoglobulins, also called antibodies, are proteins the white blood cells secrete. They are essential for combating infectious diseases.
“There are a number of factors that can affect how well we produce antibodies and maintain their levels,” explained Dr. Anna Phillips, from the University of Birmingham, in a press release. “There are some we have no control over, such as age, heritability or illness, but our general state of health can also affect their levels: stress, diet, exercise, alcohol, and smoking can all influence those levels.”
Phillips says that it remains to be seen exactly how saliva samples could be used in check-ups, since researchers need to better understand the line at which the secretion rate should be considered a cause of concern. “We could certainly say that, if found to be extremely low, it would be a useful early indicator of risk,” she said.
The team believes its next step should be a larger, longitudinal study to follow up and investigate the link between their findings and infectious diseases. They would also like to examine the development progression of a disease such as cancer to provide a greater understanding of the mechanisms behind the association detailed in the study.
Study: Phillips A, Carrol D, Drayson M, Der G. Salivary Immunoglobin A Secretion Rate is Negatively Associated with Cancer Mortality: the West of Scotland Twenty-07 Study. PLOS One. 2015.