Sansho: A Japanese Spice Supporting Gut, Immune, And Metabolic Health

By Pooja Toshniwal PahariaReviewed by Benedette Cuffari, M.Sc.

Introduction
Sanshools, essential oils, and antioxidants
Experimental evidence for anti-inflammatory activity
Dual modulation of beneficial and harmful microorganisms
How sansho supports digestive function
Sansho for pain relief, heart health, and metabolism
From unagi to shichimi: Sansho in Japanese cuisine
Is sansho safe?
Bridging culinary tradition and modern science
References
Further reading

Sansho (Zanthoxylum piperitum) is a Japanese spice rich in bioactive compounds that support anti-inflammatory, antimicrobial, digestive, and metabolic health. This article explores its traditional uses, culinary role, and modern scientific evidence.

Image Credit: karins / Shutterstock.com

Introduction

With its citrusy aroma, tangy bite, and characteristic tingling sensation, sansho not only enhances the flavor of meals but also carries a long history of use in Japanese cuisine and Kampo medicine. Beyond its culinary appeal, this spice is valued for its unique bioactive compounds that may promote digestive comfort, protect against inflammation, and support overall metabolic health.

Sanshools, essential oils, and antioxidants

Sansho is a rich source of bioactive compounds that contribute to its distinct flavor and health benefits. Key active ingredients present in sansho include sanshools, essential oils like limonene, β-phellandrene, citronellal, and geranyl acetate, as well as polyphenols and natural antioxidants.²

Sanshools, which include α-sanshool, β-sanshool, hydroxyl-α-sanshool, and hydroxyl-β-sanshool, are alkylamide compounds that cause the characteristic tingling, numbing, and buzzing sensations often experienced after consuming sansho. These “numbing sanshools” act on somatosensory neurons by inhibiting two-pore domain potassium (K2P) channels and modulating transient receptor potential (TRP) ion channels, producing a unique paresthesia distinct from the heat of chili peppers. Their sensory properties are closely tied to emerging research on analgesic and digestive effects. Sansho also contains numerous natural antioxidants like α-tocopherol and gallic acid derivatives that help stabilize hydroxy-α-sanshool during processing and storage while simultaneously conferring protection against oxidative stress and inflammation.^1,3

Sansho was historically used in Kampo medicine, a Japanese adaptation of traditional Chinese medicine, to improve circulation, digestion, and abdominal discomfort. In Korea, sansho has also been used as a diuretic, thus exemplifying its broader significance in East Asia.^1,3,11

Experimental evidence for anti-inflammatory activity

Glycoproteins, hydroxyl-α-sanshool, essential oils, and phenolic compounds present in sansho confer anti-inflammatory effects by suppressing the activity and production of pro-inflammatory cytokines, such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α). These compounds also inhibit cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) enzymatic activity, in addition to reducing the synthesis of prostaglandins and nitric oxide.

Preclinical studies indicate that sansho can downregulate nuclear factor kappa B (NF-κB) activity, an upstream regulator of cytokine activity and other inflammatory responses. Mechanistically, sansho and its constituents have been reported to influence nucleotide-binding domain, leucine-rich-containing family, pyrin domain-comprising 3 (NLRP3) inflammasome activation and to reduce reactive oxygen species (ROS)-mediated cellular damage.^5,8,11

In both in vitro and in vivo studies, Zanthoxylum piperitum essential oil (ZPEO) and related extracts have been shown to significantly reduce nitric oxide and pro-inflammatory cytokines in lipopolysaccharide (LPS)-stimulated macrophages, with antinociceptive effects observed in animal assays. In a murine gout model, distilled extracts of Z. piperitum decreased paw swelling and IL-1β levels, consistent with suppression of NLRP3-driven inflammation.^4,8

Dual modulation of beneficial and harmful microorganisms

When incorporated into traditional fermented foods like nukadoko, sansho (Japanese pepper) enhances the growth of lactic acid bacteria, supporting a healthier microbiome and shortening the pre-lactic acid fermentation phase. Concurrently, sansho essential oils and N-alkylamides can suppress the proliferation of harmful bacteria and fungi.⁹

Hydroxy-α-sanshool (studied primarily from the related species Z. bungeanum) has also been associated with favorable shifts in gut metabolites and microbial diversity in insulin-resistant mice, suggesting a potential for microbiome modulation; these findings are preclinical and species-specific.¹⁴

How sansho supports digestive function

Sansho consumption promotes salivation and has been linked to the secretion of gastrointestinal hormones, such as motilin, which are associated with enhanced digestive function. In Kampo medicine, sansho-containing formulations like Daikenchuto (TU-100) are widely prescribed to support intestinal motility and aid recovery from postoperative paralytic ileus.^1,3, 2

Aliphatic acid amides isolated from Z. piperitum have been reported to relax circular muscle of the gastric body and contract longitudinal muscles of the ileum and distal colon, actions that can facilitate coordinated transit.¹¹

Sanshools also engage somatosensory pathways in the gut via transient receptor potential (TRP) channels and two-pore domain potassium (K2P) channels, mechanisms implicated in motility effects of TU-100.^11,12

Through combined actions on hormone secretion, muscle motility, and microbial modulation, sansho may alleviate bloating, indigestion, and other gastrointestinal disturbances. The traditional use of sansho as a digestive aid aligns with preclinical evidence, suggesting potential benefits for using sansho in the management of functional gastrointestinal disorders and post-surgical digestive recovery.³

Sansho for pain relief, heart health, and metabolism

In addition to stimulating sensory neurons, hydroxyl-α-sanshool and related sanshools activate TRP channels. These effects can reduce the fast pain signals mediated by Aδ fibers, eliciting antinociceptive effects in animal models.⁴

By scavenging reactive oxygen species (ROS) and other free radicals, sansho prevents oxidative stress-induced damage while also supporting gastrointestinal, cardiovascular, and general metabolic health. More specifically, aliphatic acid amides from Z. piperitum inhibit acyl-CoA:cholesterol acyltransferase (ACAT) in vitro, and hydroxy-α-sanshool from Z. bungeanum improves lipid profiles and attenuates hepatic oxidative stress in high-fat diet models. TU-100 may also increase intestinal adrenomedullin and enhance motility, which can have secondary benefits for the cardiovascular/gastrointestinal systems.^{3, 12,13, 15}

From unagi to shichimi: Sansho in Japanese cuisine

Traditionally, sansho is sprinkled over grilled eel (unagi) to balance the rich, sweet glaze. Sansho may also be incorporated into noodle soups, such as ramen and miso, as well as pickles (tsukemono), to provide a tangy depth. Sansho is also a key component of shichimi togarashi, the seven-spice blend commonly used on noodles, grilled meats, and rice dishes.^1,2

Sansho is most widely available as a fine powder or whole dried berries in seasoning blends. Kinome, which are young sansho spring leaves, may also be used as a garnish that enhances the flavor of dishes while adding a vibrant green color. Modern culinary applications include sansho-infused soy sauces and condiments, which exemplify its versatility beyond traditional uses.^1,2

Sansho adds brightness to broths, hot pots, and seafood, and may also be used to prepare salad dressings, steak sauces, or vegetable glazes. Whether used as powder, whole berry, or fresh kinome, sansho elevates dishes by layering aroma, flavor, and a playful sensory effect, making it both a culinary staple and a creative seasoning.^1,2

Image Credit: masa44 / Shutterstock.com

Is sansho safe?

In vivo rodent studies using extracts or essential oil have not reported acute immunotoxicity at tested doses; however, comprehensive human safety data remain limited, and effects can vary with preparation and dose.⁴

Potential contraindications include patients with existing digestive disorders like acid reflux or gastritis, as these symptoms could be aggravated by the pungent compounds present in sansho. Individuals with allergies to peppercorns, citrus plants, or related spices are also advised to avoid sansho.

The consumption of numbing sanshools may provoke heightened sensitivity in those with neurological conditions. Pregnant and breastfeeding individuals should also exercise caution due to limited safety data.⁴

Bridging culinary tradition and modern science

In the future, randomized clinical trials should be conducted to evaluate the safety, efficacy, and dosage of sansho for human health applications. The integration of sansho into functional foods, nutraceuticals, and dietary supplements presents opportunities to harness its multifaceted bioactive profile. With continued study, sansho may emerge as a natural agent that bridges culinary tradition and modern health innovation, while potentially contributing to the prevention and management of metabolic, inflammatory, and infectious conditions. 

References

1. Mitani, T., Yawata, Y., Yamamoto, N., et al. (2023). Stabilization of Hydroxy-α-Sanshool by Antioxidants Present in the Genus Zanthoxylum. Foods 12(18), 3444. DOI:10.3390/foods12183444, https://www.mdpi.com/2304-8158/12/18/3444.
2. Yamasaki, K., Fukutome, N., Hayakawa, F., et al. (2022). Classification of Japanese Pepper (Zanthoxylum piperitum DC.) from Different Growing Regions Based on Analysis of Volatile Compounds and Sensory Evaluation. Molecules 27(15), 4946. DOI:10.3390/molecules27154946, https://www.mdpi.com/1420-3049/27/15/4946.
3. Díaz-Guerrero, P., Panzani, S., Sanmartin, C., et al. (2025). “Pepper”: Different Spices, One Name—Analysis of Sensory and Biological Aspects. Molecules, 30, 1891. DOI:10.3390/molecules30091891, https://www.mdpi.com/1420-3049/30/9/1891.
4. Donald, G. R., Fernandes, P. D., & Boylan, F. (2016). Antinociceptive Activity of Zanthoxylum piperitum DC. Essential Oil. Evidence-Based Complementary and Alternative Medicine. DOI:10.1155/2016/3840398, https://www.hindawi.com/journals/ecam/2016/3840398/.
5. Park C., Oh, P., & Lim, K. (2009). Inhibitory effect of phytoglycoprotein (115 kDa) on the expression of TNF-α and interleukin-1β via inhibition of MAP kinase in primary cultured mouse thymocytes, Bioscience, Biotechnology and Biochemistry 73(10);2196-2202. DOI:10.1271/bbb.90277, https://academic.oup.com/bbb/article-abstract/73/10/2196/5947874.
6. Lee J., Lee S., & Lim, K. (2014). Preventive effects of ZPDC glycoprotein (24 kDa) on hepatotoxicity induced by mercury chloride in vitro and in vivo, Cell Biochemistry and Function 32(6); 520-529, DOI:10.1002/cbf.3046, https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/cbf.3046
7. El Tayeb, N. S., Younish, N. A., Mouneir, S. M., et al. (2025). LC-MS/MS profiling of Zanthoxylum piperitum (L.) DC. Leaves cultivated in Egypt, isolation of its bioactive components, and interrelationships with anti-ulcerative activities: In vitro and in vivo approaches, molecular docking, and dynamics studies. Journal of Ethnopharmacology, 350, 119984. DOI:10.1016/j.jep.2025.119984, https://www.sciencedirect.com/science/article/abs/pii/S0378874125006695.
8. Kim, S. W., Jeong, S. H., Kim, J. U., et al. (2025). Zanthoxylum piperitum Benn. Attenuates Monosodium Urate-Induced Gouty Arthritis: A Network Pharmacology Investigation of Its Anti-Inflammatory Mechanisms. Pharmaceuticals, 18(1), 29. DOI:10.3390/ph18010029, https://www.mdpi.com/1424-8247/18/1/29.
9. Ono, H., Nishio, S., Tsurii, J., et al.. (2014). Effects of Japanese pepper and red pepper on the microbial community during nukadoko fermentation. Bioscience of Microbiota, Food, and Health 34(1);1-9. DOI:10.12938/bmfh.2014-011, https://www.jstage.jst.go.jp/article/bmfh/34/1/34_2014-011/_article.
10. Heo, Y., Han, G., Mun, H. Y., et al. (2025). Biocontrol Potential and Growth-Promoting Effects of Freshwater Trichoderma Strains against Plant Pathogenic Fungi in Red Pepper. The Plant Pathology Journal 41(3):392-408. DOI:10.5423/PPJ.OA.02.2025.0019, https://ppjonline.org/journal/view.php?doi=10.5423/PPJ.OA.02.2025.0019.
11. Kono, T., Shimada, M., Yamamoto, M., et al. (2015). Complementary and synergistic therapeutic effects of compounds found in Kampo medicine: Analysis of daikenchuto, Frontiers in Pharmacology 6(159). DOI:10.3389/fphar.2015.00159, https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2015.00159/full.
12. Hasebe, T., Ueno, N., & Musch, M. W. (2016). Daikenchuto (TU-100) shapes gut microbiota architecture and increases the production of ginsenoside metabolite compound K. Pharmacology Research & Perspectives 4(1). DOI:10.1002/prp2.215, https://bpspubs.onlinelibrary.wiley.com/doi/10.1002/prp2.215.
13. Wang, L., Fan, W, Zhang, M., et al. (2019). Anti-obesity, regulation of lipid metabolism, and attenuation of liver oxidative stress effects of hydroxy-α-sanshool isolated from Zanthoxylum bungeanum on high-fat diet-induced hyperlipidemic rats. Oxidative Medicine and Cellular Longevity. DOI:10.1155/2019/5852494, https://www.hindawi.com/journals/omcl/2019/5852494/.
14. Xu, F., Zhu, Y., Lu, M., et al. (2022). Effects of Hydroxy-Alpha-Sanshool on Intestinal Metabolism in Insulin-Resistant Mice. Foods 11, 2040, DOI:10.3390/foods11142040, https://www.mdpi.com/2304-8158/11/14/2040.
15. Park, Y., Lee, W. S., An, S., & Jeong T. (2007). Human acyl-CoA: cholesterol acyltransferase inhibitory activities of aliphatic acid amides from Zanthoxylum piperitum DC. Biological and Pharmaceutical Bulletin 30(1); 205-207. DOI:10.1248/bpb.30.205, https://www.jstage.jst.go.jp/article/bpb/30/1/30_1_205/_article.

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Last Updated: Sep 14, 2025