When it comes to understanding how your genes impact your health, methylation and other epigenetic mechanisms sit at the heart of it all. Methylation is a small chemical change with big biological consequences — one that helps control which genes are turned “on” or “off,” influencing everything from your metabolism and immune function to how fast you age.
Let’s dive into what methylation is, how it works, and why it’s the key biological process measured by the cutting-edge TallyAge Test.
The Basics: What Is Methylation?
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In simple terms, methylation is a biochemical process in which a methyl group — a small cluster made of one carbon and three hydrogen atoms — attaches to a molecule, like DNA, proteins, or other cellular components.
When this chemical modification happens on DNA, it’s called DNA methylation.
DNA methylation doesn’t change your DNA sequence — instead, it influences how your genes behave. Think of it like punctuation in a sentence: the same letters are there, but where you place the commas or periods changes the meaning. Similarly, methylation patterns can silence or activate genes without altering your underlying genetic code.
How the DNA Methylation Process Works
In the human genome, methylation occurs at sites called CpGs regions where a cytosine (C) nucleotide is followed by a guanine (G) nucleotide. Enzymes called DNA methyltransferases (DNMTs) attach methyl groups to the cytosine, forming methylated DNA.
This process can result in transcriptional silencing, meaning the gene in that region is effectively “turned off.” When methylation is removed — through active demethylation or other epigenetic changes — that gene may be reactivated.
These methylation processes are a cornerstone of epigenetic gene regulation — the dynamic system of turning genes on and off without changing your DNA itself. Differences in epigenetics ultimately explain why we have different types of cells, such as neurons and skin fibroblasts.
Why Methylation Matters
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Your body’s methylation processes play roles in hundreds of essential biological functions, including:
Regulating gene expression and cell differentiation
Supporting DNA repair and genomic stability
Controlling cell cycle progression and growth
Balancing hormone and neurotransmitter production
Maintaining healthy homocysteine levels for heart and brain health
Because methylation patterns affect how genes are expressed, disruptions to the methylation cycle can contribute to disease risk, cancer, and age-related changes in cell function. Less methylated DNA (or “hypomethylation”) has been linked to genomic instability, while hypermethylation of certain genes can silence tumor suppressors.
The Methylation Cycle and Nutrition
The body’s methylation cycle depends on nutrients from your diet — particularly those involved in one-carbon metabolism, such as:
Folic acid (vitamin B9)
Vitamin B12
Choline
Betaine
Methionine
These nutrients act as methyl donors, supplying the carbon and hydrogen atoms needed for methylation reactions throughout the body. A compound called S-adenosylmethionine (SAMe) is considered the body’s universal methyl donor, transferring methyl groups to DNA, RNA, proteins, and lipids.
A diet lacking in these nutrients — for example, a vegetarian or vegan diet without adequate B12 supplementation — can disrupt methylation balance. On the other hand, eating dark leafy greens, legumes, and whole grains rich in folate can help support optimal methylation.
Methylation and Aging
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As we age, DNA methylation patterns naturally shift. Certain regions of DNA become less methylated, while others become hypermethylated, altering gene expression and contributing to the biological aging process.
Scientists can measure these shifts in methylation patterns across thousands of CpG sites in the genome to produce an indicator of biological age — how old your body is at the cellular level, rather than by calendar years.
The TallyAge Test measures DNA methylation using your cheek cells, helping you see how your unique methylation profile compares to your chronological age. This insight allows you to track how your lifestyle, nutrition, and habits are influencing your epigenetic aging trajectory — and where you can take action.
What Affects Your Methylation?
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Several environmental factors and lifestyle choices can alter your DNA methylation patterns over time, including:
Diet and nutrient intake
Stress and sleep quality
Exposure to toxins or pollutants
Physical activity levels
Alcohol and smoking
Even postnatal development and early life nutrition can shape long-term epigenetic inheritance, influencing how genes are expressed throughout your lifespan.
The Future of Methylation Research
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In the field of molecular biology, methylation is being studied as both a marker and a mechanism of aging and disease. New tools in sequencing and epigenetic profiling allow researchers to identify differential methylation across tissues and track how interventions — from diet to exercise to supplementation — can reshape epigenetic control.
Understanding and supporting healthy methylation processes may be one of the most promising frontiers in longevity science. By maintaining proper methylation reactions, you help your cells respond dynamically to the environment, preserve DNA repair mechanisms, and promote long-term physical health.
The Bottom Line
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Methylation may be nanoscopic, but its impact is massive. This small chemical tag influences nearly every system in your body — from how your genes are expressed to how your cells age.
Tracking your DNA methylation patterns with the TallyAge Test provides a powerful window into how you’re aging biologically and helps you take a proactive, science-backed approach to longevity.
Because when you understand your methylation, you understand your biology — and your potential to age better.
References
Johnson AA et al. The role of DNA methylation in aging, rejuvenation, and age-related disease. Rejuvenation Res 2012; https://doi.org/10.1089/rej.2012.1324
Seale et al. Making sense of the ageing methylome. Nat Rev Genet 2022; https://doi.org/10.1038/s41576-022-00477-6
Moore and Fan. DNA methylation and its basic function. Neuropsychopharmacology 2013; https://doi.org/10.1038/npp.2012.112
Shokhirev et al. CheekAge: a next-generation buccal epigenetic aging clock associated with lifestyle and health. Geroscience 2024; https://doi.org/10.1007/s11357-024-01094-3
Shokhirev et al. CheekAge, a next-generation epigenetic buccal clock, is predictive of mortality in human blood. Front Aging 2024; https://doi.org/10.3389/fragi.2024.1460360
Shokhirev and Johnson. Various diseases and conditions are strongly associated with the next-generation epigenetic aging clock CheekAge. Geroscience 2025; https://doi.org/10.1007/s11357-025-01579-9
What is methylation?
Methylation is a biochemical process in which a methyl group — made of one carbon and three hydrogen atoms — attaches to a molecule like DNA, proteins, or other cellular components. When it happens on DNA, it’s called DNA methylation, and it helps control which genes are turned “on” or “off” without changing your DNA sequence.
Why is methylation important for health and aging?
Methylation regulates gene expression, supports DNA repair and genomic stability, controls cell growth, and maintains healthy hormone and neurotransmitter balance. As we age, DNA methylation patterns shift — some regions become less methylated, others more — altering gene expression and contributing to the biological aging process.
What affects your DNA methylation patterns?
Your methylation can be influenced by diet, nutrient intake, stress, sleep, toxins, physical activity, alcohol, and smoking. Even early-life nutrition shapes long-term epigenetic inheritance. The TallyAge Test measures these DNA methylation patterns to show how your lifestyle and habits are influencing your biological age.
