Tea and coffee have often been the protagonists of scientific research. The effects of their consumption, associated with health benefits but also some risks, have been assessed in several studies. Among the last ones a work by Uppsala University (Sweden) reported how tea consumption would leave a trace at a genetic level. In fact, in women who drink it, epigenetic variations have been detected, that is, chemical changes that “light” or “switch off” the genes. These include genes that interact with the metabolism of estrogen and the process of onset of cancer. However, further data are necessary to confirm the derivation of these epigenetic variations from the consumption of tea and whether these are beneficial for the body, as Professor Daniela Lucini, Head of the Humanitas Section of Exercise Medicine explains.
The study
Previous research had provided data on the correlation between coffee intake and genetic factors, while the relationship with tea was less explored. In the past, it had emerged that tea and coffee consumption could play a role in modulating the risk of anti-inflammatory diseases. Researchers thus tried to see if these mechanisms were mediated by epigenetic variations.
In the study published in Human Molecular Genetics, they analyzed DNA samples from more than three thousand adults and identified a “brand” of tea consumption in 28 different genomic regions. Epigenetic changes were observed only in women. The consumption of coffee in both sexes was not related to any epigenetic variation.
But why is there a difference compared to men? Among the genes found under the magnifying glass of scientists, there were also genes involved in the metabolism of estrogen. In addition – as scientists point out – other studies have already associated the consumption of tea with a reduction in these female hormones; finally, women tend to drink more tea than men and therefore it is more difficult to find statistically significant associations in the male sex.
Genes and environment
The possible impact of lifestyle in determining the risk of certain pathologies also concerns genetic aspects: “Diet, stress, and cigarette smoking can play a role through a direct mechanism on the aspects of DNA duplication and epigenetic modifications. These are important – Professor Lucini points out – and promising data. This study seems to show how drinking tea can also modulate the expression of genes. However, it is still too early to draw definitive conclusions’.
“Researchers themselves have taken into account to a certain extent the possible confusing factors associated with lifestyle. In fact, it is likely that those who follow certain healthy habits will also follow others who contribute to a healthier lifestyle. For example, those who drink tea regularly may not drink sweetened carbonated drinks at all and follow a much more balanced diet, perhaps with lots of fruit and vegetables. On the contrary – continues the expert – whoever drinks coffee could also smoke “.
Nevertheless, the study recalled the role of the active components of tea. Among the substances contained in tea, besides caffeine, there are polyphenols such as catechins, flavonoli or L-teanine, an amino acid. Especially epigallocatechins, antioxidant polyphenols, found particularly in green tea, have gained the attention of research.
Study evidence will need to be further strengthened by research before concluding on the health effects of these epigenetic changes and the different expression of genes: “It is often difficult to go that way and isolate the effect of exposure to a single element, for example within the diet. The message to be received is that a balanced and healthy diet is not only useful to maintain a weight shape but it can be able to influence on the direct molecular mechanisms including those associated with the regulation of genes,” concludes the professor.
