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June 27, 2017 – That morning or midday beverage may have a greater effect on our genes than previously thought, especially if you happen to be female and consume tea on a regular basis. New evidence from a group of investigators at Uppsala University shows that tea consumption in women leads to epigenetic changes in genes that are known to interact with cancer and estrogen metabolism. Findings from the new study were published recently in Human Molecular Genetics in an article entitled “Tea and Coffee Consumption in Relation to DNA Methylation in Four European Cohorts.”
“Both coffee and tea have been suggested to play an important role in modulating disease-risk in humans by suppressing tumour progression, decreasing inflammation and influencing estrogen metabolism,” the authors wrote. “These mechanisms may be mediated by changes in DNA methylation.”
In the current study, the research team investigated if coffee and tea consumption may lead to epigenetic changes. Previous studies have suggested that both coffee and tea play a key role in modulating disease risk in humans by suppressing tumor progression, decreasing inflammation, and influencing estrogen metabolism, mechanisms that may be mediated by epigenetic changes.
“To investigate if DNA methylation in blood is associated with coffee and tea consumption we performed a genome-wide DNA methylation study for coffee and tea consumption in four European cohorts (N = 3,096),” the authors stated. “DNA methylation was measured from whole blood at 421,695 CpG sites distributed throughout the genome and analysed in men and women both separately and together in each cohort. Meta-analyses of the results and additional regional-level analyses were performed.”
The results showed that there are epigenetic changes in women consuming tea, but not in men. Interestingly, many of these epigenetic changes were found in genes involved in cancer and estrogen metabolism. However, the study did not find any epigenetic changes in individuals drinking coffee.
“After adjusting for multiple testing, the meta-analysis revealed that two individual CpG-sites, mapping to DNAJC16 and TTC17, were differentially methylated in relation to tea consumption in women,” the authors penned. “No individual sites were associated in men or the sex-combined analysis for tea or coffee. The regional analysis revealed that 28 regions were differentially methylated in relation to tea consumption in women. These regions contained genes known to interact with estradiol metabolism and cancer.”
The findings from this study highlight the role of pharmacologically active components in tea being involved in cancer and estrogen metabolism, which can reflect that health effects related to tea consumption might be due to epigenetic changes.
“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,” explained lead study investigator Weronica Ek, Ph.D., a researcher in the department of immunology, genetics, and pathology at Uppsala University. “Women also drink higher amounts of tea compared to men, which increases our power to find an association in women.”
It has previously been demonstrated that compounds in tea called catechins lead to epigenetic changes in vitro and in cultured cancer cells, arguing that some of the health effects of tea may be mediated by epigenetics. However, this study did not provide evidence to support whether it is healthy or not to drink tea—further research is needed to understand how the epigenetic changes found in this study affect human health.
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