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Your DNA is the instruction manual you are born with, and it barely changes during your life. But which instructions actually get used — which genes are switched on or off, in which parts of the body, and how strongly — is controlled by a second layer of chemical “notes” written on top of the DNA. Scientists call this layer the epigenome. Unlike your DNA, it changes constantly, it responds to your environment, and, importantly, it can be shaped by the choices you make every day. This is the basis of epigenetics, and it matters a great deal for cancer.

What Epigenetics Means

Cells control their genes in three main ways. The first, DNA methylation, adds tiny chemical tags (called methyl groups) onto the DNA that usually switch a gene off. The second, histone modification, changes the spool-like proteins that DNA wraps around, loosening or tightening the packaging so genes become easier or harder to read. The third uses small RNA molecules that act as extra dimmer switches, fine-tuning how much of a gene is used [1].

These changes decide whether a gene is switched on or silenced, and in cancer the control system goes wrong in predictable ways. Protective “tumour suppressor” genes — the body’s natural brakes on cancer, such as CDKN2A, BRCA1, MLH1, and VHL — get tagged and switched off at the very moment they are needed [4]. At the same time, a broad loss of tags elsewhere in the genome makes chromosomes unstable and can switch cancer-driving genes back on [4]. And a tightening of the DNA packaging by enzymes called HDACs silences genes that would normally help cells mature properly or self-destruct when they are damaged [5].

Diet as an Epigenetic Regulator

A 2018 paper in Nature Communications showed how the food we eat plugs directly into this system, because the molecules that write epigenetic tags are themselves built from nutrients [2]. The “on/off” acetyl tags are made from acetyl-CoA, a molecule your body produces from carbohydrates and fats — so what you eat helps set how many tags are available. The methyl tags are made from a molecule called SAM, which your body builds from an amino acid (methionine) using folate, vitamin B12, and choline as helpers. If your diet is short on these nutrients, your cells struggle to place methyl tags correctly [2].

Vitamins, Polyphenols, and Epigenetic Drugs

A 2020 review in Critical Reviews in Food Science and Nutrition looked at whether vitamins and plant compounds can act as gentle “epigenetic drugs” — nudging these tags back toward a healthier pattern that may help prevent or undo cancer-linked changes [3]. It highlighted folate (which supports methylation), vitamin-A-related retinoids (which help control how open the DNA is), and several plant polyphenols — sulforaphane from broccoli, resveratrol from grapes, and EGCG from green tea — as having believable epigenetic anti-cancer effects in laboratory studies. The authors were careful to add that turning this into real treatment depends on getting the dose right, on how much of each compound the body actually absorbs, and on the fact that the same compound can behave differently in different situations [3].

The Epigenetic Clock and Biological Age

One of the most striking discoveries in this field is that these methylation tags can be read like a clock to estimate a person’s biological age. The Horvath clock, introduced in 2013, reads the tag pattern at 353 spots on the DNA to estimate age across many different tissues and cell types [6]. The later Levine PhenoAge model added clinical health markers and turned out to predict disease and death risk better than simply counting birthdays [7]. The gap between this biological age and your actual age reflects wear and tear on the body. Faster epigenetic ageing — driven by chronic stress, poor nutrition, disrupted sleep, smoking, and inactivity — is linked to substantially higher cancer risk [8]. The encouraging flip side is that exercise, better diet, and lower stress can slow this clock down [8].

Epigenetic Inheritance: Passing It On

Epigenetic tags are not completely wiped clean between generations. Studies of famines, toxic exposures, and conditions in the womb suggest that some of these tags can be passed down across one to three generations — a phenomenon called transgenerational epigenetic inheritance [9]. This has real implications for cancer: harmful exposures in parents or grandparents may nudge cancer risk in their children and grandchildren, even without any change to the DNA letters themselves [9].

Clinical Epigenetics

Epigenetics is already part of cancer treatment today. Drugs that strip away methyl tags (azacitidine, decitabine) and drugs that block the HDAC packaging enzymes (vorinostat, romidepsin) are approved treatments, used mainly for blood cancers [10]. A newer class, EZH2 inhibitors such as tazemetostat, blocks a specific tag-writing enzyme in certain lymphomas [11]. In other words, the epigenome is not just a passive diary of your life — it is an active system that medicine can target.

References

1. Feinberg AP (2018) The key role of epigenetics in human disease prevention and mitigation. N Engl J Med 378:1323–1334.
2. Zhang T and Kutateladze TG (2018) Diet and the epigenome. Nat Commun 9:3375.
3. Nur A et al. (2020) Vitamins as epidrugs. Crit Rev Food Sci Nutr 61:3843–3857.
4. Baylin SB and Jones PA (2011) A decade of exploring the cancer epigenome. Nat Rev Cancer 11:726–738.
5. Kanwal R and Gupta S (2012) Epigenetic modifications in cancer. Clin Genet 81:303–311.
6. Horvath S (2013) DNA methylation age of human tissues and cell types. Genome Biol 14:R115.
7. Levine ME et al. (2018) An epigenetic biomarker of aging for lifespan and healthspan. Aging 10:573–591.
8. Alegría-Torres JA et al. (2011) Epigenetics and lifestyle. Epigenomics 3:267–277.
9. Skinner MK et al. (2010) Epigenetic transgenerational actions of environmental factors. Trends Endocrinol Metab 21:214–222.
10. Dawson MA and Kouzarides T (2012) Cancer epigenetics: from mechanism to therapy. Cell 150:12–27.
11. Morera L et al. (2016) Targeting histone methyltransferases and demethylases in clinical trials. Clin Epigenetics 8:57.

Featured image created using Google Gemini AI.