It’s widely known that drinking tea and coffee is good for you- that’s your caffeine induced all nighters justified- but until now the mechanisms behind their health benefits have been elusive.
It turns out that popping the kettle on for a cuppa can help with reducing the risk of certain illnesses including heart disease, with coffee drinking proven to consistently show lower risk of overall mortality. Both coffee and tea can have direct consequences on DNA, modulating various factors associated with disease.
The largest study of its kind was conducted in the Netherlands with 15,789 participants of European and African American ancestries to analyse genetic effects of tea and coffee in an epigenome-wide association study (EWAS). Results were published this year with the study analysing epigenetic changes across the beverage drinkers.
But what are epigenetics? Epigenetics describes the inheritance of characteristics in ways other than through the DNA sequence itself. This works via chemical tags attached to DNA that can regulate whether genes are switched on or off depending on the environment. Through this, external factors can regulate DNA and gene expression, for example, alcohol can cause illness in the liver through epigenetic changes.
One of the most common epigenetic mechanisms is DNA methylation where a methyl group is added or removed from certain sections of DNA. DNA methylation levels change with age, sex and lifestyle factors- including drinking tea and coffee. The study found that health outcomes of coffee consumption are associated with DNA methylation at 11 different sites in the genome. One specific site revealed links with reducing the risk of fatty liver disease and others revealed roles for lipid metabolism in liver cells. Through these, coffee can act to reduce damage to liver function.
Furthermore, coffee consumption has been linked with a lower risk of other diseases including obesity, type 2 diabetes mellitus and several forms of cancer. Health benefits can arise directly from the bioactive compounds present in coffee as well as through epigenetic modification. For instance, reduced risk of neurodegenerative disease is associated with caffeine, and chlorogenic acids found in coffee have antioxidant properties helping reduce stress in the body.
Despite many studies revealing positive aspects of drinking coffee, there have been other studies warning of the downsides to it. Some studies have found evidence that high intake of coffee is related to increasing cardio-vascular disease risk factors such as increasing cholesterol and blood pressure. However, it seems that moderate amounts of coffee pose little threat, with health benefits outweighing health hazards.
Whilst tea and coffee can have an effect on your genes, a huge genome-wide association study (GWAS) revealed that your genes can also predispose you to certain foods. A study completed in 2020, in Japan, using genetic data from 165,084 Japanese people found that there are several loci in the genome associated with various dietary habits including tea and coffee consumption. Looks like science can finally explain those 15 cups of tea a day.
The screening involved looking for single base changes in the DNA sequence called single nucleotide polymorphisms (SNPs) that align to consumption of different foods. One of the elucidated SNPs was linked to higher coffee and tea consumption alongside lower alcohol consumption in a gene known as the ALDH2 gene. This method can also be used for investigating genetic links to illness, and through investigating dietary habits can unravel links between diet and disease.
Investigating the properties and effects of tea and coffee on DNA modifications and through the chemicals present can help with generating novel therapies to target disease. Although there are positive and negative effects associated with the drinks, health benefits seem to win out, which sounds like a good excuse for a coffee break if ever I heard one.
Image: Richard Pearson via Flickr