It seems that we can't get enough of tea; statistics show that almost 80 percent of households in the United States drink it. But do you know what this popular beverage does once it passes our lips? New research sheds some light on how tea affects gene expression.
Study leader Weronica Ek, of Uppsala University in Sweden, and colleagues found that drinking tea appears to trigger epigenetic changes in women that are associated with cancer and the metabolism of the hormone estrogen.
However, whether these epigenetic changes protect against cancer or drive the disease remain to be seen.
The researchers recently published their findings in the journal Human Molecular Genetics.
Epigenetics refers to the study of changes in gene expression that can be passed to future generations. It looks at how external factors, such as environment and lifestyle, affect which genes are switched on and off, and how this influences one's own health and the health of offspring.
Previous research has shown that what we eat and drink can affect the expression of genes. One study published last year, for example, found that a typical Western diet may lead to epigenetic changes by altering gut bacteria.
For this latest study, Ek and colleagues set out to investigate whether consumption of tea and coffee - two of the most popular beverages in the U.S. - might lead to epigenetic changes in men and women.
Tea caused epigenetic changes in women, but not men
To reach their findings, the researchers analyzed the data of 3,096 adults across four European cohorts.
The team looked at the participants' tea and coffee consumption and assessed their blood samples for DNA methylation, which is an indicator of changes in gene expression.
In each cohort, the researchers looked at how tea and coffee intake affected the gene expression of men and women, together and separately.
The results revealed no DNA methylation changes in either sex as a result of coffee consumption.
Tea consumption, however, was associated with alterations in DNA methylation across 28 genomic regions among women. In particular, the researchers found that tea intake appeared to alter the expression of DNAJC16 and TTC17, which are genes associated with estrogen metabolism and cancer.
Tea consumption did not lead to any changes in DNA methylation among men, the team reports.
"Previous studies have shown that tea consumption reduces estrogen levels which highlights a potential difference between the biological response to tea in men and women," says Ek. "Women also drink higher amounts of tea compared to men, which increases our power to find association in women."
Overall, the researchers believe that their findings indicate that tea consumption may trigger epigenetic changes in women that are related to cancer, though they caution that further research is needed to determine whether this effect is positive or negative.