What Is Pu’erh Tea? Fermentation, Flavour and Research
Pu’erh (also spelt pu-erh or puer) is one of the most distinctive teas in the world. It’s dark, earthy and smooth, and some aged cakes sell for the price of a fine wine. It’s also popular online for claims about digestion and weight. This guide explains what pu’erh is, how it’s made, and what the research does and doesn’t show.
Where does pu’erh come from?
Pu’erh is named after Pu’er, a town in Yunnan province in south-western China. For centuries, tea from the region was pressed into cakes and bricks so it could be carried by horse caravans along the “Tea Horse Road” into Tibet and beyond. Along the way, and in storage, the tea slowly changed, developing a deeper, mellower flavour.
Like green and black tea, pu’erh comes from Camellia sinensis, usually a large-leaf variety grown in Yunnan.
How is it made?
What sets pu’erh apart is microbial fermentation. Most “black” or “fermented” teas are really oxidised by the leaf’s own enzymes. Pu’erh is also changed by microbes, such as yeasts and moulds, over time.
There are two main styles:
- Raw (sheng) pu’erh is pressed and then left to age naturally, sometimes for decades. Young sheng can taste bright and astringent. With age it becomes darker and smoother.
- Ripe (shou) pu’erh uses a faster process developed in the 1970s, called “wet piling” (wo dui). Leaves are piled, moistened and turned over several weeks, speeding up fermentation. Ripe pu’erh is dark, earthy and very smooth from the start.
What’s in it?
Fermentation changes the chemistry of the leaf. Compared with green tea, pu’erh generally has fewer catechins and more of compounds formed during fermentation, such as theabrownins, along with gallic acid, caffeine and various polysaccharides. Caffeine levels vary, but they’re usually similar to other teas.
Pu’erh and gut bacteria
A 2021 review in Food Chemistry gathered research on pu’erh’s compounds and the gut microbiome, the community of bacteria living in the digestive tract (Liu et al., 2021). The authors described how pu’erh components changed gut bacteria and related markers in a number of studies.
It’s important to know that most of this research was done in animals or in the lab. The review itself noted that human studies are needed to know whether the same effects happen in people drinking the tea.
Pu’erh and weight: a small human trial
One of the few human trials was published in Nutrition Research in 2011 (Kubota et al., 2011). Thirty-six Japanese adults who were pre-obese or overweight took a pu’erh tea extract or a placebo daily for 12 weeks. The extract group had a small reduction in average body weight and BMI compared with placebo.
That sounds encouraging, but it’s one small, short study, it used a concentrated extract rather than brewed tea, and the results haven’t been widely confirmed in larger trials. For context, Cochrane’s review of green tea for weight loss found the effect was too small to matter clinically.
Pu’erh and blood sugar enzymes
A 2019 systematic review in Nutrition & Diabetes looked at whether pu’erh can block two digestive enzymes, alpha-glucosidase and alpha-amylase, which break down starches into sugars (Yang et al., 2019). The review found that pu’erh extracts inhibited these enzymes in many lab experiments.
Again, these are mostly test-tube and animal results. They don’t show that drinking pu’erh affects blood sugar in people, and nobody should use it in place of diabetes advice or treatment.
Being upfront about the evidence
Pu’erh is a fascinating tea, and researchers are interested in how fermentation changes it. But most of the evidence so far is from labs and animals, and the human research is small. “Promising but unproven” is a fair summary.
How to brew pu’erh
Pu’erh is very forgiving and rewards experimenting:
- Rinse first. Pour boiling water over the leaves and tip it out after a few seconds. This “wakes up” compressed leaves and rinses off dust.
- Use boiling water. Unlike green tea, pu’erh likes water at a full boil.
- Short steeps, many times. In the traditional “gongfu” style, use more leaf and steep for 10–30 seconds, then repeat many times. In a mug, steep for 2–4 minutes.
- Store it well. Keep cakes in a clean, dry place away from strong smells. Raw pu’erh needs some airflow to age.
Who should take care?
Pu’erh contains caffeine, so keep track of your intake if you’re pregnant, breastfeeding or caffeine-sensitive. As with any tea, buy from reputable sources and store it properly to avoid unwanted moulds. Check with your pharmacist if you take regular medication.
The bottom line
Pu’erh is a unique fermented tea with a long history and a rich, earthy flavour. Research on gut bacteria, weight and blood sugar enzymes is interesting, but mostly in animals or the lab, with only small human trials of extracts. Enjoy it for its taste and tradition rather than as a health fix.
This article is general information only and is not medical advice. It is not about any specific product. Talk to your GP or pharmacist about your own health.
References
- Liu JY, et al. Effects of bioactive components of Pu-erh tea on gut microbiomes and health: a review. Food Chem. 2021. https://pubmed.ncbi.nlm.nih.gov/33743430/
- Kubota K, et al. Improvements of mean body mass index and body weight in preobese and overweight Japanese adults with black Chinese tea (Pu-Erh) water extract. Nutr Res. 2011. https://pubmed.ncbi.nlm.nih.gov/21745623/
- Yang CY, et al. Inhibitory effects of pu-erh tea on alpha glucosidase and alpha amylase: a systemic review. Nutr Diabetes. 2019. https://pubmed.ncbi.nlm.nih.gov/31455758/
