A study by US scientists has suggested that losing the ability to smell could be linked to a greater risk of death.

The study of more than 3,000 people aged 57 to 85 found that 39 per cent of subjects who failed a simple smelling test died within five years. The results were published in the science journal PLOS ONE on 1 October, Reuters has reported.

"Compared to a person with a normal sense of smell, a person with an absent sense of smell has three times greater risk of dying within a five-year span," Dr. Jayant Pinto, the study's lead author, told Reuters.

Pinto is an associate professor of surgery at the University of Chicago’s medical department.

Pinto said: “This tells us that your sense of smell is a great indicator of your overall health.”

The 39 per cent who had passed away within the five year study scored low test scores in the smell test, making four or five errors. This compares with 19 per cent who had a moderate sense of smell and just 10 per cent who had a healthy sense of smell (who had made 0-1 errors).

The smells in the test included rose, leather, peppermint, fish and orange. Those with the poorest sense of smell were still at the greatest risk even after factors such as age, nutrition, smoking habits and poverty were taken in to account.

But Pinto said: “We think the loss of the sense of smell is like the canary in the coal mine. It doesn’t directly cause death, but it’s a harbinger, an early warning that something has gone badly wrong.”

The scientists say that they are now doing more research to study the link. They say that one possibility is that losing the ability to smell could mean less regeneration and cell repair in the body. Also, a poor sense of smell might mirror a lifetime’s exposure to bugs and pollution, they say.

However, Nirmal Kumar, a consultant head and neck surgeon who is the honorary secretary of ENT UK – an association for ear, nose and throat specialists, told the Daily Mail that people losing their sense of smell should not panic. He said the study was interesting but questioned the reliability of the smell test used.