Can the simple saliva tests Kim Kardashian loved REALLY tell you your ‘biological age’? Experts weigh in as companies launch DIY kits

Some of us are desperate to know the answer. Others can’t imagine anything worse.

But if you want to catch a glimpse of your future to see how old your body is, look no further: companies are increasingly trying to solve this riddle for you.

Biological age tests, which were featured on the latest season of Keeping Up With the Kardashians, can theoretically distinguish between your chronic and biological age.

The first refers to the number of years you live, while the second is an estimate of the deterioration of your body, based on subtle markers in your DNA.

Biological age tests, which were featured on the latest season of Keeping Up With the Kardashians, can theoretically distinguish between your chronic and biological age. Pictured: One biological age test available online for £149 offers ‘insight into genetic predispositions to ageing and long-term health’

However, new research suggests they may not be as accurate as once thought in determining your true ‘biological age’.

American scientists who conducted the study warned that their findings ‘important implications for the interpretation of commercial biological age tests’. and will help improve their reliability and usefulness in the future’.

Epigenetics is a field that has been around for a long time. Dozens of companies produce their own saliva and blood clock tests.

However, questions have been raised about whether epigenetics itself can be used to recommend lifestyle changes.

The traditional view of aging is that it is caused by a slow buildup of damage at the cellular level. Like a car, parts of us break down or wear out.

It can be hard to put a number on this. That’s where an epigenetic clock test comes in.

They cost between £150 and £300 on average and measure what are known as DNA methylation levels.

This is the degree to which special molecules called methyl groups have attached to the DNA in your cells.

On a recent episode of The Kardashians, Kim, mother Kris and sister Khloe all took tests and discovered that Khloe’s biological age was reportedly 28 — 11 years younger than her actual age, 39.

Kim, 43, was meanwhile given a biological age of 34, while Kris was six years younger than her actual age

They are described as barnacles that attach themselves to the hull of a ship and slow the ship down.

In the study, researchers from Harvard University investigated how stem cells in a tissue or organ influence the epigenetic clock.

Tests on mice showed that there were differences per body part. Stem cells in skeletal muscles, trachea and even blood, for example, appeared to be less old than more mature cells.

For comparison, stem cells have a similar epigenetic age as adult cells in the skin and intestines.

Writing in the diary, Stem Cell Reportsthe researchers said that muscle and blood cells “which undergo age-related changes in abundance register a different epigenetic age than bulk tissues.”

Further experiments also showed that the epigenetic age of a stem cell was related to the rate at which the stem cell divides and produces new cells.

They concluded that the epigenetic age of a tissue is influenced by the activity of stem cells.

However, stem cells can change in response to aging, injury or disease, they noted, meaning that results from biological aging tests may not be accurate.

Their findings “will help to refine the reliability and usability of the tests in the future,” the researchers said.

The first epigenetic tests took place after German geneticist Professor Steve Horvath developed an aging clock at the University of California, Los Angeles in 2011.

He measured specific epigenetic patterns associated with aging.

This allowed him to develop a model that could estimate a person’s biological age based solely on methylation levels.

In blind testing of hundreds of people, the biological age figures matched the chronological age of the majority, suggesting they are accurate.

This meant that the clock was a useful comparison tool to see how much younger or older your cells are than those of the average person your age.

Since then, companies such as Zymo Research and Epimorphy and Chronomics have released tests.

On a recent episode of The Kardashians, Kim, mother Kris and sister Khloe all took tests and discovered that Khloe’s biological age was reportedly 28 — 11 years younger than her actual age, 39.

Kim, 43, was given a biological age of 34, while Kris was six years younger than her actual age.