What Is Methylation?
- The methylation cycle starts with homocysteine
- One of the molecules affected in this pathway is involved in making DNA.
- Another, MTR or methionine synthase, converts homocysteine to methionine. It needs vitamin B12 and 5-MTHF to function.
- SAM has a methyl group attached to it, which it can “give” to our DNA, causing DNA methylation.
- The end result of the methylation cycle is methionine, but also produces other compounds important for antioxidant defense and affects folate metabolism
But if the methylations cycle is less efficient — like if the activity of your MTHFR is reduced — homocysteine can build up because not enough of it is being converted to methionine. High homocysteine levels are a big risk factor for many diseases — from inflammation and heart disease, to diabetes, autoimmune diseases (like psoriasis), neurological issues, cancer, and others [R].
If you’re curious to read more, download the Methylation Bonus that goes in-depth about the science, specific SNPs to look out for, and how I was able to overcome my MTHFR issues.
Types of Methylation
Methylation is the basis of epigenetics, the study of how the environment affects our genes. Our environment, our lifestyle, and diet are all factors that can turn genes on or off. The patterns of methylation and demethylation presented here can have an impact on health, aging, and chronic disease like cancer [R].
Although over- and undermethylation can both be harmful, it’s important to consider which genes are being “turned on or off”. Activating or deactivating some key regions can have the most serious health complications (such as hypomethylation of the so-called repeat sequences in cancer) (R).
1) DNA Hypermethylation
A healthy body has a certain level of methylation. Irregular and over-methylated DNA can change a gene, preventing it from producing what it’s meant to. Changes in the placement of methyl groups can cause diseases (R).
Some researchers have even used the amount of methylation in certain genes as a biological clock, as it occurs in individual genes is proportional to age. The implications include, but are not limited to:
- Causes cancer
- Lowers immune system function
- Damages brain health
- Lowers energy and exercise
- Quickens aging
It can inactivate certain tumor-suppressor genes and stop the expression of mRNAs that play a role in tumor suppression (R).
Additionally, external, environmental factors can alter methylation. In other words, while abnormal methylation in DNA can replicate itself and be passed down, this balance can also be altered by everything around us (R).
2) DNA Hypomethylation
Too little of methylation can also be harmful.
If there is insufficient methylation in the body, it can cause genomic instability and cell transformation (R).
And although hypermethylation was thought to be more common in cancers, cancers seem to equally have hypomethylation. Hypomethylation can be beneficial for cancer short-term, but it may also speed up cancer growth (R).
This methylation in cancer has been described as “too much, but too little”. In cancer, some parts of the DNA are overmethylated, and other parts undermethylated, leading to a complete dysbalance of the normal methylation cycle (R).
And aside from cancer, hypomethylation may also contribute to inflammation (leading to atherosclerosis) and autoimmune diseases, such as lupus, multiple sclerosis (R).
3) DNA Demethylation
DNA demethylation can also play a role in the formation of tumors (R).
But during embryo development, this process is crucial. Scientists have long struggled to understand how complex biochemical messages are communicated in the embryo to enable identical stem cells to develop into specialized cells, tissues, and organs. Demethylation happens in early embryos and is essential for stem cells to be able to differentiate into different cell types. Parts of DNA are turned on or off, and then modified via demethylation again for healthy development to take place (R).
Methylation And Ageing: the “Epigenetic Clock”
Methylation is not a black-or-white phenomenon. It’s not symmetrical in any way. And it’s not just a matter of if your DNA is more or less methylated, but how. It turns out that methylation increases during childhood, but most of the DNA is being methylated at that time. As we age, just the specific regions of DNA, the CpG islands become overmethylated while the rest of the DNA is undermethylated. This is the hallmark of aging (R).
Based on the pattern of CpG methylation, scientists can now predict someone’s age. This is called the “epigenetic clock” — a biomarker of aging — the specific methylation pattern of aging common to most people that tells us about our “functional age”. But there is also a “drift” in each individual, a pattern slightly different in each person from the general population, called the “epigenetic drift” that is still being explored (R).
Basically, based on your DNA methylation, scientists might be able to tell you your “epigenetic age” and compare it to your actual age. Based on this, you could be epigenetically younger or older. And if you’re epigenetically older, then this points to a greater chance of health problems (R).