A new observational study has failed to convincingly prove the theory that people with a poor sense of smell have a higher risk of early death.

The study involving 2,200 participants in two communities in the United States was conducted by Michigan State University. One of the first that investigated this alleged link, the study wanted to explain exactly why smell may be correlated with mortality.

The study was published in the journal Annals of Internal Medicine.

The study result does seem to suggest a link between loss of the sense of smell and death, but it comes with so many caveats as to render this conclusion inconclusive.

The study discovered that a poor sense of smell was associated with a nearly 50 percent higher risk of death within the next decade for adults older than 70. While the study didn't prove cause and effect, this link is enough to make some experts wonder whether seniors' sense of smell should be tested alongside their other vital signs.

Using data from two U.S. communities, researchers tracked 2,200 participants between the ages of 71 and 82 across 13 years. Those that demonstrated a poor sense of smell had a 50 percent higher risk of death in 10 years time. The sense of smell of the participants was tested using 12 common scents.

"The association was largely limited to participants who reported good-to-excellent health at enrollment, suggesting that poor sense of smell is an early and sensitive sign for deteriorating health before it is clinically recognizable," Honglei Chen, senior author and a professor at Michigan State University, said.

Chen also said they don’t have a reason for more than 70 percent of the increased risk. She said researchers need to find out what happened to these.

Three diseases that can make you smell, and what foods can help reduce bad body odor. Photo courtesy of Pexels, Public Domain

It’s also not clear if the participants in this study always had a poor sense of smell, or whether this trait only come about more recently. Critics noted it was beyond the scope of this observational study to explain exactly why smell might be correlated with mortality.

The prevailing wisdom is that a poor sense of smell might have little impact on the overall risk of death.