Simple urine test can tell how much our body has aged

Beijing: Scientists have identified a promising new marker of ageing in urine that may help predict the risk of developing age-related diseases and even death. Researchers, including those from Sichuan University in China, found that a substance indicating oxidative damage increases in urine as people get older.

The study, published in the journal Frontiers in Aging Neuroscience, also describes a way to easily measure the levels of this marker in human urine samples. The new marker potentially provides a method to measure how much our body has aged – our biological rather than chronological age, researchers said. This could help predict our risk of developing age-related disease, and even the likely time-frame for our death, they said.

While everyone born in the same year has the same chronological age, the bodies of different people age at different rates. This means that, although the risk of many diseases increases with age, the link between our age in years and our health and lifespan is relatively loose. Many people enjoy long lives, relatively free of disease, while others suffer chronic illness and premature death. Some researchers consider normal ageing 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. We need to be able to measure biological age to know whether treatments to slow ageing – which may be possible in the future – are effective, researchers said. 

One mechanism thought to underlie biological ageing involves a molecule vital to our survival – oxygen – in what is called the free radical theory of ageing. “Oxygen by-products produced during normal metabolism can cause oxidative damage to biomolecules in cells, such as DNA and RNA,” said Jian-Ping Cai from National Center of Gerontology in China. “As we age, we suffer increasing oxidative damage, and so the levels of oxidative markers increase in our body,” Cai said. One such marker called 8-oxo-7,8-dihydroguanosine or 8-oxoGsn results from oxidation of a crucial molecule in our cells called RNA. 

The researchers measured 8-oxoGsn in urine samples from 1,228 Chinese residents aged 2-90 years old, using a rapid analysis technique called ultra-high-performance liquid chromatography. “We found an age-dependent increase in urinary 8-oxoGsn in participants 21 years old and older,” said Cai. “Therefore, urinary 8-oxoGsn is promising as a new marker of ageing,” Cai said.

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 oestrogen levels that happens during menopause, as oestrogen is known to have anti-oxidant effects.