The first recordings of the processing and consumption of tea for medicinal purposes in China are found in Shennong’s ‘Shénnóng Běn Cǎo Jīng’, a classical text recognized as China’s first Materia medica (Heiss & Heiss, 2007). It is estimated to have been written over two-thousand years ago during the Han dynasty, a time known historically for great advancement and scientific development. The text involves an extensive list of over 300 herbal medicines used for all varieties of ailments and diseases (Heiss & Heiss, 2007). Found within the pages of this ancient encyclopedia are the first details and descriptions of leaves derived from the Camellia sinensis plant, known famously across the world today as Tea.

Both the anti-inflammatory (cooling) and detoxifying (purging) abilities of tea were heavily discussed with recipes and prescriptions provided for numerous conditions such as internal heat, dampness, and Qi deficiency (Zhang, 2014). By Tang dynasty (AD 618-907) tea had become a very sought-after commodity and highly prized amongst the royal elite. To make trading across borders and difficult long terrain easier and more economic, Chinese merchants began packing large amounts of tea leaves into compressed bricks (Powell, 1998). This allowed the Chinese to reach distant regions such as Tibet, India and Nepal and build a thriving tea trade. Over many years and trading exhibitions through difficult climates and extreme altitudes, the Chinese started to notice changes in the tea leaves transforming from vibrant green to amber to eventually turning dark. Tasting the tea themselves, they noticed not only had the colour changed, also the flavour had evolved from sweet, grassy astringent to livelier, richer and fuller (Powell, 1998). These early tea traders noticed that during their travels, the tea leaves underwent an aging and fermentation process whereby environmental microbes acted on the leaves, causing biological and enzymatic changes. Slowly, as word spread, this new flavour and style of tea because highly popular, especially by high officials and tea connoisseurs for its unique flavour and medical properties.

This “aged tea” variety was revolution in the world of tea drinking and processing as it involved a non-enzyme-related oxidation process very different from both green and white varieties of the same time period. Pu-erh was originally administered as an herbal medicine added to soups or used as a culinary herb to help flavour bland recipes. Pu-erh tea was said to be first cultivated and grown in Yunnan, the southernmost subtropical province of China, which to this day claims to be the birthplace of tea. Quiet astoundingly, some of the same leaves picked for the use of Pu-erh today are said to come from these original tea plants found deep within the rainforests Ge et al., 2021).

Enormous care and attention are taken when picking the leaves to ensure the plant and environment are not damaged or diseased to help preserve the ancient forests. Once gathered, the leaves are then selected for grading based on their quality in shape, texture, and colour. From here, the leaves go through a special withering procedure where they are spread out over large bamboo racks and immediately heated to halt any oxidation from occurring. Once the leaves have been heated, they are then rolled in by hand on large mats they are left out in the sun to dry. Once dried the resulting product is referred to as Mao Cha, the raw product of Pu-erh tea which can be either transformed into a Sheng (aged) Pu-erh or Shou (Ripe) Pu-erh depending on the tea master’s desire. Either making Sheng Pu-erh or Shou Pu-erh, once the leaves have reached their desired fermentation level, they go through a compression process before being left to sit for a minimum of three months to allow for any fermentation to stabilize.

The processing of Pu-erh introduces beneficial bacteria and probiotics which are said to encourage blood sugar control, curb hunger and assist in weight management. Recent interest in the health benefits of Pu-erh has unveiled an array of fascinating discoveries in the field of metabolomics. New sophisticated analytical techniques along with a revived appreciation for traditional medicines opened a new perspective on the healing properties that have long been cherished by the Chinese people.

In 2022, a complete health review was conducted by the Journal of Traditional Chinese Medical Science (Jia, Rajani, Lv, Fan & Zheng 2022). This paper explored several important studies investigating the molecular functions and health potential of regular Pu-erh consumption. The review highlighted positive outcomes for a variety of conditions such as gastrointestinal inflammation and barrier integrity loss, cardiovascular disease, hepatic damage, tumour growth, and neurological diseases such as Alzheimer’s and dementia (Jia, Rajani, Lv, Fan & Zheng 2022).

Some of the major bioactive component mixtures extracted from Pu-erh tea leaves such as polyphenols, theanine, polysaccharides, gallic acid, and theabrownin have been said to possess beneficial effects on metabolic parameters and the gut. Each of these bioactive components was shown to have different metabolic parameters and act together in a multi-functional symbiotic manner. Of these bioactive components, Polyphenols are found in abundance in Pu-erh tea (Goldberg, 2009).

These polyphenols have been shown time after time to have the greatest effect on lowering sLOX-1 levels, a soluble lectin-like oxidized LDL receptor that has been heavily linked to obesity (Ge et al., 2021). These same polyphenols also have a strong influence on reducing circulating pro-inflammatory cytokines IL-6 and TNFa which are involved in the pathogenesis of multiple inflammatory diseases such as cardiovascular disease, cirrhosis of the liver, and diabetes (Goldberg, 2009).

Much more research is still yet to be done in the quest to uncover the magic of this ancient herbal medicine. However, with a rapidly growing population full of chronic disease and poor metabolic health, could some of the answers to our current health crisis lay within the leaves of this extraordinary plant? I say we put on the kettle and brew me some Pu-erh tea while we figure that out!

References

Ge, Y., Li, N., Fu, Y., Yu, X., Xiao, Y., Tang, Z., Xiao, J., Wu, J.-L., & Jiang, Z.-H. (2021). Deciphering superior quality of Pu-erh tea from thousands of years’ old trees based on the chemical profile. Food Chemistry, 358, 129602. https://doi.org/10.1016/j.foodchem.2021.129602

Goldberg, R. B. (2009). Cytokine and cytokine-like inflammation markers, endothelial dysfunction, and imbalanced coagulation in development of diabetes and its complications. The Journal of Clinical Endocrinology & Metabolism, 94(9), 3171-3182.Heiss, M. L., & Heiss, R. J. (2007). The story of tea: A cultural history and drinking guide. Ten Speed Press.

Jia, W., Rajani, C., Lv, A., Fan, T.-P., & Zheng, X. (2022). Pu-Erh Tea: A review of a healthful brew. Journal of Traditional Chinese Medical Sciences, 9(2), 95–99. https://doi.org/10.1016/j.jtcms.2022.04.005

Powell, D. A. (1998). Tea. Wesleyan University Press.

Zhang, L., Li, N., Ma, Z.-Z., & Tu, P.-F. (2011). Comparison of the chemical constituents of aged Pu-erh tea, ripened Pu-erh tea, and other teas using HPLC-dad-ESI-MSn. Journal of Agricultural and Food Chemistry, 59(16), 8754–8760. https://doi.org/10.1021/jf2015733

Zhang, J. (2014). Puer Tea: Ancient caravans and urban chic. University of Washington Press.