Methods & Algorithms to Measure Biological Age

Aging: it’s a process we all go through, yet it affects everyone differently. So, how old are you, really? This question may seem straightforward, but when we delve into the science of aging, the answer becomes surprisingly complex.

With the measurement of biological age, it provides a more precise measure of an individual’s overall health and aging status compared to the chronological age. So, how do scientists determine your biological age? Let’s explore some of the key methods and algorithms that can help uncover the true age of your body and mind.

Telomore Length

In the bustling city of our body, each cell represents a building, and our DNA is the master blueprint booklet. We need the read and decode the blueprint (our DNA) to build or repair the building (our body cell).

But how does this relate to aging? At the ends of our DNA strands, there are tiny protective caps called telomeres, they safeguard our DNA, ensuring the vital genetic information is preserved during cell division.

Everytime our cells divide, these telomeres shorten a little bit. They act as a buffer zone, taking the hit so that the crucial DNA sequence isn’t affected.

However, as the telomeres continue to shorten over time due to repetitive cellular repair and regeneration during aging or injury, they eventually become so short that they can no longer protect the DNA.

When this happens, the cell can no longer divide properly, indicating process of cellular aging, serving as an indicator of biological age. [1]

Telomere length is affected by a combination of factors including donor age, genetic, epigenetic make-up and environment, social and economic status, exercise, body weight, and smoking while gender has no significant effect on it[2].

DNA Methylation

Another method to estimate biological age is through the study of DNA methylation, a biochemical process that alters the activity of the DNA molecule.

As mentioned earlier, our DNA is like a blueprint booklet. DNA methylation is like placing bookmarks on certain pages of your DNA blueprint booklet. These bookmarks don’t change the words in the book, but they can change how the book is being read.

As we age, more and more bookmarks get placed throughout our DNA. Smart scientists identified a pattern of these bookmarks that changes predictably as we get older. This pattern is referred to as the DNA methylation age/ DNAm Age, or the “epigenetic clock”. It’s like a timekeeper hidden in our DNA that gives clues about our biological age, which is how old our body appears to be on the inside.

In 2013, scientist Steve Horvath, studied the DNA from lots of people of different ages and found 353 places in our DNA where these sticky notes seemed to change as we get older. He made a formula, or “clock,” that can guess how old you are based on these 353 places, which is known as ‘Horvath clock’ (1st generation).

Up to date, newer generation ‘clocks’ have been introduced which includes: Hannum clock, GrimAge, DunedinPACE, DunnedinPoAm etc. As the new generation of clock, the more accurate the prediction as well as the stronger the connection between biological clock and disease occurence, as well as lesser variation in the age range.

Clinical Data & Biomarkers

Scientist also created model that calculated phenotypic age based on nine clinical markers most significantly associated with mortality (albumin, creatinine, serum glucose, c-reactive protein, lymphocyte percentage, mean cell volume, red cell distribution width, and alkaline phosphatase) and chronological age. Then, they selected 513 CpG sites that were the most accurate in predicting phenotypic age and that formed DNA-m PhenoAge.[3]

Choosing the best algorithm to predict your biological age

Imagine if there’s a way to know how well you’re aging, like checking if you’re on the winning side against health issues related to getting older. That’s what biological age testing aims to do.

But sadly, due to the commercial demand, some products created have strayed away from the scientific backbone of these tests. And we’ve ended up with loads of products that might not really help or even give the wrong answers.

We need a kind of “aging clock” that’s really tied to the signs of aging and disease to make these tests useful. However, currently  many companies providing biological age tests do not have any published data on their algorithms and the relationship to health and disease.  Here are some keys to look at while choosing the best biological age test for yourself:

  • The test has got enough published and shares data on its relationship to disease outcomes.
  • Use a test which has been published and shares data on precision, and has the least variance.

For instance, imagine your true biological age is 60. But the test variance is 30%, that means that your sample could vary as much as 18 years if you tested the exact same sample twice.

So, if you test 1 year apart, how do you know if this is a true age related change or just an error in the measurement?

  • Understand that differences in cell types can cause differences in algorithm performance.

For instance, if someone has a viral illness and it changes the amount of B cells in their blood, it might change their aging score. Definitely you wouldn’t want a test that concludes that someone is older just because they are temporarily sick.

Therefore, choose the test that has least dependence on cell type fluctuation.

  • Always consider the latest generation of the clock which has the highest predictive value!

Nonetheless, these aging clocks are continually refined and tested to improve their accuracy and usefulness. It’s important to remember that these methods and algorithms, while promising, are extremely useful tools in our understanding of aging.


More research will undoubtedly continue to refine our understanding and measurement of biological age, with the hope of creating a healthier, longer life for all.

The science of biological age gives us the ability to look beyond our chronological years and examine the condition of our bodies and minds. Only by knowing our biological age, we can improve it through lifestyle, nutraceuticals or even latest anti-aging therapies. Never to forget: biological age is not just a number, but a window to truly understand our healthspan and how to improve it so that we can prevent frailty as we age. No one would want to spend the remaining of their lives being bed-bound with countless hospital visits!


1. Masood A. Shammas: Telomeres, lifestyle, cancer, and aging 2011 Jan; 14(1): 28–34.

2. Brouilette S, Singh RK, Thompson JR, et al. White cell telomere length and risk of premature myocardial infarction. Arterioscler Thromb Vasc Biol. 2003;23:842–846.

3. Veronika V. Erema *,Anna Y. Yakovchik,Daria A. Kashtanova, Zanda V. Bochkaeva,Mikhail V. Ivanov,Dmitry V. Sosin,Lorena R. Matkava,Vladimir S. Yudin,Valentin V. Makarov,Anton A. Keskinov,Sergey A. Kraevoy andSergey M. Yudin Biological Age Predictors: The Status Quo and Future Trends Int. J. Mol. Sci. 2022, 23(23), 15103

Functional medicine Malaysia doctor

Dr. Shirley Koeh
01 June 2023

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