What Is Chen Pi Good For?

In my clinic, chen pi is one of the most ordinary herbs on the shelf. In southern China, the oldest jars of the same peel are collected like vintage wine. Here is what chen pi is good for, why time changes it, and how to use it after a big dinner.

What is chen pi good for?

Getting a heavy, stuck stomach moving again.

Chen pi (陈皮) means “aged peel.” It is the dried rind of the mandarin orange, Citrus reticulata, and a major review in the Journal of Ethnopharmacology calls it the herb most often used to regulate Qi across thousands of Chinese medicine prescriptions. It has been used for nausea, vomiting, indigestion, poor appetite, diarrhea, cough and phlegm, and it is listed in the Pharmacopoeia of the People’s Republic of China. Chemists have identified about 140 compounds in it, and the volatile oils and the flavonoids are considered the main active groups.^[1]

In the Chinese materia medica, chen pi is acrid, bitter and warm, and it enters the Spleen and Lung. Its classical actions are to regulate Qi, harmonize the Middle, dry dampness and transform phlegm. The Middle is the Spleen and Stomach, the cooking pot of digestion.

You know dampness even if you have never used the word. It is that feeling after a huge dinner when your jeans suddenly feel two sizes too small: heavy, full, slow and puffy. The Spleen likes warmth and dryness, and it struggles under cold and damp, which is the same terrain I describe in my post on iced matcha. A warm, fragrant, drying herb gets that pot cooking again. Reading your own terrain is the work we do together inside Gut Brain Synchrony.

What is aged tangerine peel?

Any mandarin peel can be dried, but the classic comes from one place. Xinhui chen pi is made from the ‘Chachi’ mandarin in Xinhui District, Guangdong, and it carries a protected geographical indication, the same kind of protection that keeps the name champagne tied to Champagne.^[2] Researchers call Xinhui the geoherb of chen pi, the region whose peel sets the standard.^[3]

The jar in my video is about 18 years old. On my last trip to China I was introduced to a local businessman, and before he asked me for anything at all, he handed me this jar as a gesture of kindness. Only later did I learn what I was holding. It even carries an anti-counterfeit QR code.

In the clinic we mostly use peel aged about three to twelve years, and it does the job well. Chinese medicine has long taught that fresh peel is sharp and harsh, and that years of storage make it gentler and better. That is the “chen” in the name.

Why is chen pi so expensive?

Because you cannot make old peel quickly, and the best comes from one small district. The finest aged Xinhui peel sells for prices that sound absurd for dried fruit skin, and collectors stockpile it like wine.

The research describes the same market. A 2025 study of Xinhui peel notes its “great medicinal, dietary and collection values,” and that Xinhui peel on the market is often counterfeited with other varieties or origins. The authors built a DNA test to tell true Xinhui peel from peel grown elsewhere.^[3]

Does chen pi get better with age?

Its chemistry changes, and the microbes living on the peel are part of the reason.

What lives on an old peel

A team in Chengdu compared ‘Chachi’ peel stored from 1 to 30 years. A single fungal genus, Xeromyces, dominated the whole 30-year span, and the dominant fungus and bacterium on the peel, Xeromyces bisporus and Bacillus thuringiensis, were strongly associated with the peel’s key active compounds.^[4] In another study, Xeromyces made up more than 99 percent of the fungi on Xinhui peel aged 10 to 15 years, and it tracked closely with the rise of the peel’s polymethoxyflavones. Older peel also developed more floral and fruity aromas.^[5]

Xeromyces is a remarkable organism to find on an herb. Very few microbes stay active in conditions as dry as a well-stored peel, and Xeromyces bisporus has long been considered the most resilient of them, though a 2017 study found a mold, Aspergillus penicillioides, starting to grow in even drier conditions.^[6]

What aging does to the chemistry

Compared with freshly harvested Xinhui peel, peel stored for three years had less of 17 volatile compounds and less synephrine, and more phenolic acid, more of five flavonoids including hesperidin, nobiletin and tangeretin, and stronger antioxidant activity. The authors read the fall in volatile oils as a reduction in the peel’s dryness.^[7] That is the classical teaching in modern terms: new peel is harsh, old peel is mellow.

Across peel stored from 1 to 11 years, nobiletin, tangeretin and a related heptamethoxyflavone rose with storage time while hesperidin fell, and antioxidant activity increased.^[8] Aging is not one fixed recipe, though. In Guang chen pi followed over 36 months, nobiletin fell from 7.294 to 2.825 mg/g, and different microbes, Rhodococcus and Apiotrichum, came to dominate.^[9] Where and how the peel is stored shapes what it becomes.

Microbes that rebuild the flavonoids

A 2025 study of Xinhui peel aged 1 to 10 years found that its flavonoids follow a path of degradation and then resynthesis, with polymethoxyflavones steadily accumulating. Late in aging, Xeromyces dominated and correlated strongly with that buildup. The researchers then isolated a fungus from the peel, Aspergillus tubingensis, and showed directly that it converts nobiletin into a new form, 3′-demethylnobiletin.^[2]

That form has been studied in the lab, where it shows up after nobiletin is digested. In mice with chemically induced colitis-associated colon cancer, oral nobiletin lowered both the number of mice with colon tumors and the number of tumors. In the colon lining, its metabolites, including 3′-demethylnobiletin, together reached about 20 times the level of nobiletin itself, and in human colon cancer cells those metabolites acted far more strongly than the parent compound.^[10] Nobiletin itself has been studied for nerve repair: it lengthened growing fibers in sensory nerve cells and, after a sciatic nerve crush, raised the regeneration marker GAP-43 and helped axons regrow.^[11]

There is also evidence that age matters for digestion, in animals. In mice with a model of what Chinese medicine calls Spleen deficiency, peel stored more than three years relieved fatigue better than newer peel, raised the digestive hormone gastrin, strengthened a tight-junction protein in the colon wall and shifted the gut bacteria.^[12]

These are mouse and cell findings, not human ones, but they give an old observation a biological basis.

Chen pi benefits for the stomach: does it help bloating?

That is what it is used for most. The human trials test it inside formulas, with encouraging but mixed results.

Chen pi is one of the herbs in Liu Jun Zi Tang, the Six Gentlemen formula for a weak, damp digestion, known in Japan as rikkunshito. In the DREAM trial, 128 people with functional dyspepsia, the persistent fullness and discomfort of a stomach that will not settle, were randomized to rikkunshito or placebo for eight weeks. Rikkunshito improved overall treatment efficacy, and it improved fullness, early satiety and bloating at four and eight weeks.^[13] An earlier trial of 247 patients found more responders on rikkunshito, 33.6 percent against 23.8 percent, but the difference was not statistically significant.^[14]

A meta-analysis of 13 trials with 1,153 people with functional dyspepsia of the liver-stomach disharmony pattern found Chinese herbal formulas outperformed prokinetic drugs, though the trials were of poor quality. Chen pi was among the herbs prescribed most often.^[15]

On its own, chen pi has been studied mainly in animals. In an animal model of functional dyspepsia, 14 days of chen pi improved stomach emptying and intestinal transit, lowered the inflammatory markers IL-6, TNF-α and IL-1β, and shifted the gut bacteria.^[16] One human trial tested a fermented tangerine peel drink: in 72 adults with high blood fats, 55 of whom finished, eight weeks of the drink lowered body weight and triglycerides, with no adverse changes in safety tests.^[17]

The way I use it matches the tradition: a warm, aromatic cup after a heavy meal, to help the Middle do its work.

How to make chen pi tea

This is how I take it at home.

For the rest of the picture, Digestive Health: Start Here covers how I think about the gut as a whole.

Chen pi questions, answered

What is chen pi in English?

Aged tangerine peel, or dried mandarin peel. Its pharmaceutical name is Citri Reticulatae Pericarpium. Chen means old or aged, and pi means peel.

Can you eat tangerine peel?

Yes. Chen pi is both a food and a medicine in China. It is taken in tea, in food, in wine and in herbal formulas.^[1]

What is chen pi tea good for?

Fullness, bloating and heaviness after eating, the classic signs of dampness in the Middle. It is also used for a chest clogged with phlegm.

Some medicines are made in a laboratory. Some are made by time.

— Brehan Crawford, L.Ac.

References

1. Yu X, Sun S, Guo Y, et al. Citri Reticulatae Pericarpium (Chenpi): Botany, ethnopharmacology, phytochemistry, and pharmacology of a frequently used traditional Chinese medicine. J Ethnopharmacol. 2018;220:265-282. doi:10.1016/j.jep.2018.03.031
2. Tang Z, Miao Y, Lu H, Chen C, Li S, Zhang W. Aging of Citri Reticulatae pericarpium: Flavonoid metabolite dynamics, fungal community succession, and functional analysis of key transformation strains. Food Res Int. 2026;227:118220. doi:10.1016/j.foodres.2025.118220
3. Cheng Q, Tang Z, Ouyang Y, et al. MYB polymorphism molecular marker: A novel molecular marker for authenticity and geographical origin identification of Citri Reticulatae Pericarpium. Chin Herb Med. 2025;17(2):296-306. doi:10.1016/j.chmed.2025.02.006
4. Wang F, Hu Y, Chen H, Chen L, Liu Y. Exploring the roles of microorganisms and metabolites in the 30-year aging process of the dried pericarps of Citrus reticulata ‘Chachi’ based on high-throughput sequencing and comparative metabolomics. Food Res Int. 2023;172:113117. doi:10.1016/j.foodres.2023.113117
5. Huang X, Hong M, Meng Q, Zhang Y, Kou X, Ke Q. The effects of core microorganism community on flavor compounds and active substances during the aging process of Citri Reticulatae Pericarpium. Food Res Int. 2024;191:114707. doi:10.1016/j.foodres.2024.114707
6. Stevenson A, Hamill PG, O’Kane CJ, et al. Aspergillus penicillioides differentiation and cell division at 0.585 water activity. Environ Microbiol. 2017;19(2):687-697. doi:10.1111/1462-2920.13597
7. Shi J, Peng L, Chen W, et al. Evaluation of chemical components and quality in Xinhui Chenpi (‘Chachi’) with two different storage times by GC-MS and UPLC. Food Sci Nutr. 2024;12(7):5036-5051. doi:10.1002/fsn3.4154
8. Yang M, Jiang Z, Wen M, et al. Chemical Variation of Chenpi (Citrus Peels) and Corresponding Correlated Bioactive Compounds by LC-MS Metabolomics and Multibioassay Analysis. Front Nutr. 2022;9:825381. doi:10.3389/fnut.2022.825381
9. Li F, Ge K, Lu Y, et al. Dynamics of chemical profile and microbial community in 3 consecutive years reveal Rhodococcus and Apiotrichum are potential microbes contributing to quality formation of Guang Chenpi. Food Chem. 2025;473:143003. doi:10.1016/j.foodchem.2025.143003
10. Wu X, Song M, Wang M, et al. Chemopreventive effects of nobiletin and its colonic metabolites on colon carcinogenesis. Mol Nutr Food Res. 2015;59(12):2383-2394. doi:10.1002/mnfr.201500378
11. Seo TB, Jeon YA, Kim SS, Lee YJ. In Vitro and In Vivo Effects of Nobiletin on DRG Neurite Elongation and Axon Growth after Sciatic Nerve Injury. Int J Environ Res Public Health. 2021;18(17):8988. doi:10.3390/ijerph18178988
12. Sun X, Deng H, Shan B, et al. Flavonoids contribute most to discriminating aged Guang Chenpi (‘Chachi’) by spectrum-effect relationship analysis between LC-Q-Orbitrap/MS fingerprint and ameliorating spleen deficiency activity. Food Sci Nutr. 2023;11(11):7039-7060. doi:10.1002/fsn3.3629
13. Tominaga K, Sakata Y, Kusunoki H, et al. Rikkunshito simultaneously improves dyspepsia correlated with anxiety in patients with functional dyspepsia: A randomized clinical trial (the DREAM study). Neurogastroenterol Motil. 2018;30(7):e13319. doi:10.1111/nmo.13319
14. Suzuki H, Matsuzaki J, Fukushima Y, et al. Randomized clinical trial: rikkunshito in the treatment of functional dyspepsia, a multicenter, double-blind, randomized, placebo-controlled study. Neurogastroenterol Motil. 2014;26(7):950-961. doi:10.1111/nmo.12348
15. Wang C, Zhu M, Xia W, Jiang W, Li Y. Meta-analysis of traditional Chinese medicine in treating functional dyspepsia of liver-stomach disharmony syndrome. J Tradit Chin Med. 2012;32(4):515-522. doi:10.1016/s0254-6272(13)60063-1
16. Hu J, Wang X, Guo X, et al. Network analysis and experimental validation to investigate Citri Reticulatae Pericarpium against functional dyspepsia through TLR4/MyD88 by regulating the gut microbial structure. Front Pharmacol. 2025;16:1495799. doi:10.3389/fphar.2025.1495799
17. Tan F, Zheng Y, Wang C, et al. Effects of Chenpi Jiaosu on serum metabolites and intestinal microflora in a dyslipidemia population: a randomized controlled pilot trial. Front Endocrinol (Lausanne). 2025;16:1552117. doi:10.3389/fendo.2025.1552117