Thousands of people all over the world enjoy drinking tea for many reasons. Some people may drink tea for relaxation and pleasure but others may have tea for religious or traditional reasons. However, it has been reported that coffee or tea consumption can decrease the risk of several diseases, such as type 2 diabetes, cognitive decline and specific cancers. On the other hand, it has also been associated with adverse pregnancy outcomes. For example, The World Health Organization (WHO) says “for pregnant women with high daily caffeine intake (more than 300 mg per day), lowering daily caffeine intake during pregnancy is recommended to reduce the risk of pregnancy loss and low birth weight neonates.”
Given the widespread consumption of beverages and their substantial health implications, understanding environmental and genetic factors contributing to beverage choice and consumption level has important nutritional and broader public health implications. It has been reported that taste perception and preferences are heritable and play important roles in determining beverage choice and consumption. A recent Mendelian randomization analysis reported that bitter taste perception was causally associated with coffee, tea and alcohol consumption.
In this study, researchers performed a genome-wide association study (GWAS) of self-reported bitter and sweet beverage consumption among ~370,000 participants. They were enrolled in 2 stages: stage 1 included participants of European ancestry from the UK Biobank, and stage 2 included participants from 3 US-based cohorts. For the purposes of this study, coffee, tea, grapefruit juice, red wine, liquor and beer were considered bitter beverages, while sweet beverages included non-grapefruit juices and artificially and sugar sweetened beverages (SSBs). In comparing the results of stages 1 and 2, seven independent SNPs mapped to five loci were replicated for bitter non-alcoholic beverage consumption. Three SNPs, rs2813703 in/near ESRRG gene, rs1481012 in/near ABCG2 gene, and rs4410790 in/near AHR gene, demonstrated strong associations with tea consumption in participants from the UK Biobank, although they were not replicated in US cohorts. The ABCG2 gene contains loci that have previously been associated with plasma caffeine metabolites, meaning it plays a role in the body’s ability to process caffeine.
Other SNPs near caffeine-related loci, such as AHR and CYP1A1/2, were associated with tea consumption in the UK Biobank, but they were also not replicated in the US cohorts. This discrepancy between study populations could be due to the fact that tea is a major source of caffeine in the UK, but not in US populations. Replication may have been impeded by the strong cultural differences of tea drinking behaviors between the two countries. You can read more about the study here: https://www.ncbi.nlm.nih.gov/pubmed/31046077
Are you interested in learning more about your genetic tendency for tea consumption? You can login to your Genomelink dashboard to see this new genetic trait.