GERD is one of the most common digestive system disorders, and is typically linked to dietary and lifestyle factors.
Tea consumption, especially in Asian populations, has been associated with GERD, though its impact on the risk of developing GERD remains a controversial topic.
Higher quanti-tea, higher risk
Researchers at China's Jining No. 1 People's Hospital, Changhai Hospital, and Second Military Medical University carried out a meta-analysis to investigate the link between tea-drinking and the risk of GERD.
Using research databases such as Embase and PubMed, they narrowed down their search for studies published up to March 2018, and finally settled on 23 articles covering 30 studies.
They initially reported that according to the results of the meta-analysis, tea drinking had no significant link to the risk of GERD.
However, after conducting sub-group analysis based on geographical region, they found that tea consumption could indeed raise the risk of GERD in East Asia (the reverse was true in Middle Asia).
Furthermore, within the sub-group of study design, they observed a significant association between tea intake and GERD in the cross-sectional study.
In the sub-group with no symptoms, the risk of GERD was also increased in association with tea intake.
This was consistent with previous studies conducted among Chinese populations, which reported that drinking strong tea could be associated with the risk of GERD, due to an increase in pressure in the lower oesophageal sphincter (LES).
However, the researchers also acknowledged that their meta-analysis had several limitations.
The amount of tea intake was "quite heterogeneous" among the 30 studies, and there were possible confounding variables involved: the type of tea, degree of fermentation, concentration of tea polyphenols, and temperature of the tea.
In addition, some studies were based on mixed ethnicity, and these may not have taken into account the gene-environment interaction on the risk of Barrett's oesophagus, a condition brought on by acid reflux that can inflame the oesophagus and even progress into cancer.
At the same time, most of the reviewed studies were cross-sectional and case-control studies, and therefore were unable to indicate direct causality between tea intake and the risk of GERD. Furthermore, most of the studies did not clearly adjust for confounding variables.
Finally, the researchers had excluded a study that assessed tea with salt, tea with milk, and tea and coffee combined, which they said might have had an impact on GERD.
In conclusion, they wrote: "There was no significant relationship between tea consumption and the risk of GERD overall. However, in subgroup analysis, tea drinking may increase the risk of GERD in East Asia.
"This suggests that tea-drinking may be a potential risk (factor) of GERD, and it should be considered to limit the amount of intake in some GERD patients. A better designed study is needed to confirm the effect of tea on GERD."
"Association between tea consumption and gastroesophageal reflux disease: A meta-analysis"
Authors: Hongying Cao, et al.