From bee venom facials to mercury wrinkle cream, people are obsessed with staying young. But how exactly do we measure age? Researchers in China think they may have figured it out.

A new study published in Frontiers in Aging Neuroscience suggests a biomarker found in urine may be the key to measuring a person's biological age – and it may also help predict one's risk of age-related diseases.

We age in two ways: chronologically and biologically. People born on the same day will always have the same chronological age. A person’s biological age, on the other hand, is how old they appear to be on a cellular level. This changes based on genetics, lifestyle, and environment. 

Some research suggests aging is a disease, and understanding why people age at different rates may help better inform how we treat certain diseases.

A substance found in urine called – don’t hold your breath on this one, 8-oxo-7,8-dihydroguanosine (8-oxoGsn for short) – could serve as a biomarker for telling just how old a person's body is. According to the study, 8-oxoGsn increases in urine as people get older, making it a suitable biomarker for biological age.

Researchers analyzed urine samples from 1,228 Chinese residents aged between 2- and 90-years-old to detect concentrations of 8-oxo-Gsn. They found the substance begins to increase at the age of 20, and continues to increase over time with age.

Ironically, the oxygen that keeps us alive is also believed to be the culprit behind aging. The process of oxidation creates cellular damage in our bodies through the “free radical theory of aging” (FRTA). Oxygen in the body splits into single atoms with unpaired electrons that, in search of an electron partner, wreak havoc on cells, proteins, and DNA, causing oxidative stress. 8-oxoGsn is what's leftover after RNA oxidizes.

"As we age, we suffer increasing oxidative damage, and so the levels of oxidative markers increase in our body," said study author Dr Jian-Ping Cai in a statement. Previous studies have shown that the substance increases in urine with age and correlates with certain diseases. 

In men and women, 8-oxoGsn levels were about the same, with the exception of post-menopausal women who showed higher levels. This could be because estrogen is known to have antioxidant effects and their estrogen levels decreased during menopause. 

Aptly named the "ultra-high-performance liquid chromatography", the rapid analysis technique can test up to 10 urine samples an hour. Researchers say they can collect data over a short span of time instead of an entire lifetime.  

The team hope to validate their findings in a larger study.