What do scientists find in Vietnamese tea leaves? Mostly, a great deal of variety. Studies of northern Vietnamese tea have measured wide differences in caffeine, catechins and amino acids between samples, high genetic diversity among old Shan trees, and clear effects of cultivar and processing on leaf chemistry. This article summarises five peer-reviewed studies in plain language. It covers agronomy, chemistry and genetics only; it makes no claims about health.
Five studies at a glance
| Study | Samples | Main finding |
|---|---|---|
| Yoshida et al., 2006 | 135 tea plants from northern Vietnam | All assamica type; wide variation in caffeine, catechins and free amino acids; midland tea as valuable for breeding as Shan |
| Nguyen et al., 2019 | Green and purple Trung du tea | Purple form richer in anthocyanins; green form richer in catechins |
| Nhu-Trang et al., 2023 | 28 teas from northern and southern Vietnam | Chemistry varies with processing, region and cultivar; green and raw Pu’er-style tea from wild or old northern trees had higher polyphenols than southern oolong and northern black tea |
| Bui et al., 2025 | 60 Shan tea trees | High genetic diversity, three regional groups; Suoi Giang trees lower in tannins and several catechins than Cao Bo trees |
| Phan et al., 2025 | 97 tea samples from central Vietnam | Genetic diversity of central Vietnamese tea assessed with RAPD markers |
A wide chemical range in northern tea
In the early 2000s, Japanese and Vietnamese researchers collected 135 tea plants across the northern provinces and analysed their caffeine, catechins and free amino acids (Yoshida et al., 2006). All belonged to the large-leaf Camellia sinensis var. assamica. Most were rich in caffeine and catechins, and some contained more than 1.5% (dry weight) of a methylated catechin known as EGCG3″Me. The authors concluded that midland (Trung du) tea had breeding value comparable to Shan tea. For breeders, this range is raw material: it allows cultivars to be selected for particular flavours or processing needs.
Green and purple midland tea
Midland tea comes in green-leaved and purple-tinged forms. A 2019 study in the International Food Research Journal compared them and found that the purple form contained more anthocyanins, the pigments that give it colour, while the green form contained more catechins. In the cup, such differences affect colour and astringency.
Wild, old and cultivated teas compared
A 2023 study in the journal Molecules analysed 28 Vietnamese teas, from wild and old trees in the north to cultivated gardens in the north and south, for caffeine, gallic acid and catechins. Green tea and raw Pu’er-style tea made from wild or old northern trees had higher polyphenol content than southern oolong and northern black tea. Caffeine and catechin levels varied with processing method, region and cultivar. The lesson for buyers is simple: the same leaf can become very different teas depending on how it is made.
Genetic diversity of Shan tea
A 2025 study in Sains Malaysiana examined 60 Shan tea trees with 30 pairs of SSR markers, together with leaf form and chemistry. It found high genetic diversity, with diversity indices from 0.47 to 0.82, and the trees fell into three groups by region. Trees from Suoi Giang had lower levels of tannins and several catechins than trees from Cao Bo in Ha Giang. These results support treating each highland area as distinct, rather than “Shan tea” as one product.
Diversity is not limited to the north. A 2025 study of 97 samples from central Vietnam, from Nghe An to Hue, also used DNA markers to map genetic variation among tea plants there.
What this means in practice
- Origin matters at the level of the area. Trees a few hundred kilometres apart can differ in chemistry; name the area, not just the country.
- Processing matters as much as the plant. Green, black, oolong and fermented teas from the same leaf differ widely.
- Breeding has room to grow. The diversity of midland and Shan tea gives Vietnamese breeders a wide base for new cultivars.
- Ask for data on your lot. If chemistry matters for your product, ask your supplier for laboratory analysis of the specific lot.
See also which tea cultivars Vietnam grows and is northern Vietnam part of tea’s homeland.
Frequently asked questions
Is Vietnamese tea high in catechins?
Studies of northern Vietnamese tea found most samples rich in catechins, with wide variation between plants, cultivars and processing methods.
What type of tea plant grows in northern Vietnam?
The large-leaf assamica variety, in both old local forms (midland and Shan) and improved cultivars.
Does processing change the chemistry of tea?
Yes. A 2023 study of 28 Vietnamese teas found that caffeine and catechin levels varied with processing method, as well as region and cultivar.
Does this article make health claims?
No. It reports measurements of leaf chemistry and genetics only.
Sources
- Yoshida K. et al. (2006), Bulletin of the National Institute of Vegetable and Tea Science 5: 33–46: agris.fao.org
- Nguyen T.L. et al. (2019), International Food Research Journal: agris.fao.org
- Nhu-Trang T.-T. et al. (2023), Molecules 28(8): 3470: mdpi.com
- Bui K.T. et al. (2025), Sains Malaysiana 54(3): 797–814: ukm.my
- Phan T.P.N. et al. (2025), Indian Journal of Agricultural Research 59(6): 868–875: arccjournals.com
Need lot-level data for your product? Contact TRAVINA to discuss laboratory testing for the teas you buy.
