Thai Nguyen tea is a type of Vietnamese green tea and contains several types of catechins, including EGCG, EGC, ECG, and EC. However, the exact proportions of these catechins may vary depending on a variety of factors, such as the growing conditions, harvesting time, and processing methods.
Studies have shown that Thai Nguyen tea has a high content of total catechins, with EGCG being the most abundant catechin, followed by EGC. The ratio of EGCG to EGC in Thai Nguyen tea has been reported to be around 3:1. Additionally, Thai Nguyen tea has been found to have a higher content of gallic acid derivatives, which may contribute to its bitterness and astringency.
It's important to note that the catechin content in tea can be affected by various factors, such as the quality of the tea leaves, the growing conditions, and the processing methods. Furthermore, the bioavailability of catechins may also depend on individual factors, such as a person's metabolism and gut microbiome.