A promising new aging biomarker has been found in urine. According to Chinese researchers, urinary 8-oxoGsn increases as people get older, and could be used to measure biological rather than chronological age. They believe that the disconnection between chronological age and lifespan requires better biomarkers of aging
The research, published today in Frontiers in Aging Neuroscience, also describes a way to measure levels of this marker in human urine samples.
Some researchers consider normal aging to be a disease, where our cells accumulate damage over time. The rate of this cellular damage can vary from person to person, and may be dictated by genetics, lifestyle, and the environment we live in. This cellular damage may be a more accurate indication of our biological age than the number of years since we were born.
"Oxygen by-products produced during normal metabolism can cause oxidative damage to biomolecules in cells, such as DNA and RNA," explains Jian-Ping Cai, a researcher involved in the study. "As we age, we suffer increasing oxidative damage, and so the levels of oxidative markers increase in our body."
The biomarker 8-oxo-7,8-dihydroguanosine, or 8-oxoGsn for short, results from oxidation of RNA. In previous studies, Cai and colleagues found that 8-oxoGsn levels increase in urine with age in animals. To see if this is true for humans as well, the researchers measured 8-oxoGsn in urine samples from 1,228 Chinese residents aged 2-90 years old, using ultra-high-performance liquid chromatography (UHPLC). "We found an age-dependent increase in urinary 8-oxoGsn in participants 21 years old and older," said Cai.
Interestingly, levels of 8-oxoGsn were roughly the same between men and women, except in post-menopausal women, who showed higher levels. This may have been caused by the decrease in estrogen levels that happens during menopause, as estrogen is known to have anti-oxidant effects.