To understand these effects, we first need to take a step back and look at some biochemistry – specifically how our bodies use a molecule called vitamin B9, more commonly known as folic acid or folate. Found in fruit and veg, as well as fortified cereals, folate is the first step in the biochemical pathway that leads to DNA methylation, the major epigenetic mark on our DNA. And, as we have mentioned, methylated DNA is silent DNA, meaning that the genes within it are switched off.

Once it enters the body, folate is transformed into tetrahydrofolate (THF), thanks to a couple of chemical reactions. The next step is to stick a methyl group, made up of carbon and two or three hydrogen atoms, onto THF, making methyl-THF. Methyl-THF plays a crucial role in DNA methylation, by generously donating its methyl group on to yet another molecule, creating methionine. And finally, after a few more chemical reactions, methionine ultimately acts as the source for the methyl groups that get pasted onto DNA. Here’s a handy outline:

Folate…is converted to…tetrahydrofolate (THF)…which is converted to…methyl-THF…which donates its methyl group to…methionine…which donates methyl groups to make…methylated DNA

Clear as a dry martini, huh?

But how does alcohol fit into the picture? Studies have shown that booze can stop us from absorbing folate properly from food. And it can also have a more direct impact. When your body breaks down alcohol, it creates a chemical called acetaldehyde, which is more toxic to your cells than alcohol itself.

In fact, acetaldehyde is mostly to blame for the pounding headache and puking that comes free with every big, boozy night out. But as well as wreaking havoc on your brain and bowels, acetaldehyde also affects folate metabolism. It can block some of enzymes involved in the DNA methylation pathway, as well as directly destroying methyl-THF.

So that’s the science bit – but what does this mean for us?