Home Ingredients Black Catechu (Acacia catechu, Khair)

Black Catechu (Acacia catechu, Khair)

Acacia catechu (Senegalia catechu)
Evidence Level
Preliminary
0 Clinical Trials
5 Documented Benefits
1/5 Evidence Score

Black catechu, also called khair or kattha, is an extract made from the heartwood of the Acacia catechu tree (now also classed as Senegalia catechu), used in Ayurvedic tradition. Water extracts of the heartwood are rich in the flavan-3-ols catechin and epicatechin. No human trial has tested black catechu swallowed on its own. In supplements it appears mainly in two-ingredient blends: with Baikal skullcap in UP446 and the prescription medical food flavocoxid, and with white mulberry root bark in UP1306 (AmLexin). Joint comfort results for these blends range from a small maker-funded pilot that favored the blend over placebo to a larger 12 week trial that did not, and two cognition trials found no clear difference from placebo. Flavocoxid has been linked to rare cases of liver injury. Catechu is also an ingredient of betel quid, a different exposure classed as carcinogenic.

Studied Dose No human trial has tested black catechu extract alone, so it has no studied dose. In blends: UP446 250 or 500 mg a day; flavocoxid 250 or 500 mg twice daily; UP1306 (AmLexin) 400 mg a day; UP326 300 mg a day, and a UP326 product containing 51 mg of the heartwood extract.
Active Compound Heartwood extract of Acacia catechu, rich in the flavan-3-ols (+)-catechin and (-)-epicatechin, with smaller amounts of epicatechin gallate, epigallocatechin gallate and other flavonoids; caffeine and flavanol dimers have also been identified in catechu. The traditional product (kattha, khoyer) is made by boiling the wood in water and drying the brew.

Benefits

Source of catechin and epicatechin (lab analysis)

Laboratory analyses show that water extracts of the heartwood are rich in catechin and epicatechin, with smaller amounts of epicatechin gallate and epigallocatechin gallate; caffeine has also been identified. These are the same flavan-3-ol family found in tea, but no human study has measured what catechu catechins do when the extract is taken alone.

Joint comfort in blends with Baikal skullcap (other products)

In a pilot trial of 15 adults per group, UP446 500 mg a day scored better than placebo on WOMAC pain, the stated primary outcome, and on function over 90 days; the trial was Unigen-funded and unregistered. A Unigen-funded 1 week UP446 trial and a 12 week flavocoxid trial compared the blends only with naproxen, with no placebo group. These results belong to the blends, not to catechu alone.

Joint comfort with a catechu and white mulberry blend (other product)

In 135 adults with knee osteoarthritis, the UP1306 blend at 400 mg a day for 12 weeks did not improve WOMAC pain, stiffness or function more than placebo; all groups improved. Only the change in urine CTX-II, a cartilage breakdown marker, differed from placebo. Unigen funded the trial. It tested the blend, not catechu alone.

Reaction time and memory tests in blend trials (other products)

In 83 healthy adults, a skullcap and catechu blend (UP326) for 30 days did not change reaction time overall versus placebo, although faster responses appeared in weeks 2 and 3; most authors were Unigen staff. In a registered 4 week trial of 85 healthy adults, cognitive scores rose equally on the blend and on placebo.

Immune cell and gut muscle activity (animal and lab work)

In mice, heartwood extracts raised antibody responses, and in mouse immune cells grown in the lab they increased macrophage activity and lowered TNF-alpha and nitric oxide. In isolated guinea pig gut tissue, an extract relaxed colon muscle contractions. These are animal and laboratory results that have not been tested in people.

Mechanism of action

1

Catechin antioxidant activity (laboratory and animal data)

Heartwood extracts are rich in catechin and epicatechin, and a review describes potent antioxidant activity in cell and animal studies, proposed to underlie anti-inflammatory and tissue-protective effects seen there. Whether swallowed catechu changes antioxidant or inflammation markers in people has not been tested for the extract alone.

2

COX and LOX enzyme pathways (blend data)

Blends that pair catechu with Baikal skullcap, such as UP446 and flavocoxid, are described by their developers as inhibiting COX-1, COX-2 and 5-lipoxygenase, the enzymes that make prostaglandins and leukotrienes. This has been studied for the blends, mostly in laboratory and animal work, and not for catechu on its own.

3

Gut muscle relaxation (guinea pig tissue)

In isolated guinea pig colon and ileum, an Acacia catechu extract reduced spontaneous muscle contractions in a way that resembled calcium channel blockade, more strongly in the colon. It also inhibited some gut pathogens in culture at higher concentrations. These findings have not been tested in people.

Clinical trials

Side effects and drug interactions

Common Potential side effects

No human safety study of black catechu extract taken alone has been published; reviewers note that few human studies of the heartwood extract exist. Safety data come from blends.
Liver: flavocoxid (Limbrel), a prescription medical food blending baicalin from Baikal skullcap with catechins from Acacia catechu, was linked to acute liver injury in 4 women in a US Drug-Induced Liver Injury Network case series (causality highly likely in 3, possible in 1); all recovered within 3 to 12 weeks of stopping. LiverTox describes minor enzyme elevations and rare clinically apparent liver injury with flavocoxid. These reports concern the blend; which ingredient is responsible was not established. Stop and see a doctor if you notice yellow skin or eyes, dark urine or unusual tiredness.
In a claims study of 3,337 flavocoxid users, hospitalized liver injury (3.2 per 1,000 person-years) and hypersensitivity pneumonitis, a lung reaction (1.1 per 1,000 person-years), were uncommon and, in the authors' view, only minimally higher than with prescription NSAIDs. Controlled trials of flavocoxid, UP446 and UP1306 that ran blood tests over 12 weeks or less reported no clinically meaningful changes.
Betel quid: catechu (kattha) is a traditional ingredient of betel quid, which also contains areca nut, betel leaf and slaked lime and often tobacco. IARC classifies betel quid with or without tobacco, and areca nut, as carcinogenic to humans, attributing the nitrosamines formed in saliva to areca nut. IARC does not classify catechu separately, and swallowing a catechu extract is a different exposure, but avoid chewing betel quid.
Pregnancy and breastfeeding: not studied in people; avoid unless a clinician advises otherwise.

Important Drug interactions

No drug interaction studies of black catechu extract alone have been published.
Medicines or supplements that can affect the liver: because blends of catechu with Baikal skullcap have been linked to rare liver injury, ask your doctor before combining catechu blends with such products or with regular alcohol use.
Pain relievers and anti-inflammatory medicines: catechu blends were compared with naproxen and celecoxib but not tested in combination with them. Do not change a prescribed dose on your own, and tell your doctor or pharmacist about any supplement you take.

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Frequently asked questions about Black Catechu (Acacia catechu, Khair)

What is black catechu?

Black catechu, also called khair or kattha, is an extract made by boiling the heartwood of the Acacia catechu tree and drying the brew. It is used in Ayurvedic tradition and is rich in catechin and epicatechin, flavan-3-ols related to those in tea. In supplements it is mostly found in blends rather than on its own.

Has black catechu been tested on its own in people?

No trial has tested a swallowed black catechu extract on its own. Human studies of the extract alone are limited to dental use such as a mouth rinse used by young children. The swallowed human trials all used blends with Baikal skullcap or white mulberry, so their results cannot be credited to catechu alone.

How do AmLexin and Attenutin relate to black catechu?

Both are Unigen blends that contain an Acacia catechu heartwood extract. AmLexin (UP1306) pairs it with white mulberry root bark and was studied at 400 mg a day; Attenutin (UP446) pairs it with Baikal skullcap. Their trial results describe the blends, and each has its own page.

Is Black Catechu safe, and does it have side effects?

Safety of the extract alone has not been studied in people. Flavocoxid, a prescription medical food that combines catechu catechins with Baikal skullcap, has been linked to rare liver injury that resolved after stopping. Catechu is also chewed in betel quid, which IARC classes as carcinogenic to humans, as it does areca nut, the main ingredient; avoid betel quid and talk to a clinician before using catechu blends.

What is the recommended dosage of Black Catechu?

There is no studied dose for catechu alone. Blends supplied it as part of 250 to 500 mg a day of UP446, 250 or 500 mg twice daily of flavocoxid, or 400 mg a day of UP1306, and one cognition product contained 51 mg of the heartwood extract. Follow the product label and ask a healthcare provider for personal advice.

What is Black Catechu used for?

NutraSmarts does not list Black Catechu under a health category. What the research covers: Laboratory analyses show that water extracts of the heartwood are rich in catechin and epicatechin, with smaller amounts of epicatechin gallate and epigallocatechin gallate; caffeine has also been identified.

Does Black Catechu interact with any medications?

Possible interactions include: No drug interaction studies of black catechu extract alone have been published. Medicines or supplements that can affect the liver: because blends of catechu with Baikal skullcap have been linked to rare liver injury, ask your doctor before combining catechu blends with such prod… If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Black Catechu?

NutraSmarts rates the evidence for Black Catechu as Preliminary (1 out of 5). It is backed by 16 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(16 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Stohs SJ, Bagchi D. Antioxidant, Anti-inflammatory, and Chemoprotective Properties of Acacia catechu Heartwood Extracts. Phytother Res. 2015;29(6):818-24. doi: 10.1002/ptr.5335.PubMedUsed to support: Review. States that water extracts of Acacia catechu heartwood are a rich source of catechin and epicatechin with smaller amounts of flavonoids, that antioxidant, anti-inflammatory and related effects have been shown in animal and cell studies, and that few human studies have ever been conducted on the efficacy or safety of the heartwood extracts; the human data it cites come from a two-ingredient combination product. The authors list an AdvoCare International affiliation and declare no conflicts.
  2. Shen D, Wu Q, Wang M, Yang Y, Lavoie EJ, Simon JE. Determination of the predominant catechins in Acacia catechu by liquid chromatography/electrospray ionization-mass spectrometry. J Agric Food Chem. 2006;54(9):3219-24. doi: 10.1021/jf0531499.PubMedUsed to support: Laboratory analysis. Developed a method to measure the predominant catechins in catechu heartwood and leaves: catechin, epicatechin, epicatechin-3-O-gallate and epigallocatechin-3-O-gallate. Caffeine, flavanol dimers and flavonol glycosides were also identified.
  3. Sunil MA, Sunitha VS, Radhakrishnan EK, Jyothis M. Immunomodulatory activities of Acacia catechu, a traditional thirst quencher of South India. J Ayurveda Integr Med. 2019;10(3):185-191. doi: 10.1016/j.jaim.2017.10.010.PubMedUsed to support: Mouse and cell study. Notes that a heartwood decoction is drunk in southern India, especially Kerala. Heartwood extracts raised antibody titers and antibody-producing spleen cells in mice, lowered the delayed-type hypersensitivity reaction, increased macrophage activity, and lowered TNF-alpha and nitric oxide while raising IL-10 in cultured cells. No human data.
  4. Micucci M, Gotti R, Corazza I, Tocci G, Chiarini A, De Giorgio M, Camarda L, Frosini M, Marzetti C, Cevenini M, Budriesi R. Newer Insights into the Antidiarrheal Effects of Acacia catechu Willd. Extract in Guinea Pig. J Med Food. 2017;20(6):592-600. doi: 10.1089/jmf.2016.0154.PubMedUsed to support: Laboratory study in isolated guinea pig gut tissue. The extract contained (-)-epicatechin and (+)-catechin and reduced spontaneous contractions of colon muscle more than ileum muscle, with a calcium-antagonist-like effect. It inhibited Campylobacter jejuni, E. coli and Salmonella in culture at about fivefold higher concentrations, without affecting Bifidobacterium or Lactobacillus. Two authors list a company affiliation (Valsambro S.r.l.). No human data.
  5. Joshi M, Patil SB. Comparison of antimicrobial efficacy of Acacia catechu mouthrinse and HiOra herbal mouthrinse and their influence on Streptococcus mutans count and Lactobacillus spp. count in children with early childhood caries. GMS Hyg Infect Control. 2025;20:Doc12. doi: 10.3205/dgkh000541.PubMedUsed to support: Randomized, double-blind controlled trial of a mouth rinse used locally, not swallowed. In 60 children aged 6 to 71 months with early childhood caries (20 per group), parents diluted 5 ml of rinse with 5 ml of water and wiped it over the teeth with gauze twice daily for 15 days; the control was plain salt water and the comparator a commercial herbal rinse (HiOra). After treatment, total salivary colony counts were lower in both herbal groups than in the control group (p = 0.034) and did not differ between the two herbal rinses (p = 0.931). Streptococcus mutans and Lactobacillus counts fell significantly within the Acacia catechu group, but they also fell within the salt water control group, so these are within-group changes. The authors declare no competing interests.
  6. Sampalis JS, Brownell LA. A randomized, double blind, placebo and active comparator controlled pilot study of UP446, a novel dual pathway inhibitor anti-inflammatory agent of botanical origin. Nutr J. 2012;11:21. doi: 10.1186/1475-2891-11-21.PubMedUsed to support: Other product (UP446, a Scutellaria baicalensis and Acacia catechu blend). Pilot trial in 60 adults aged 40 to 75 with hip or knee osteoarthritis, 15 per group: UP446 250 mg a day (125 mg twice daily), UP446 500 mg a day, celecoxib 200 mg a day or placebo for 90 days; 52 completed. The stated primary efficacy outcome was WOMAC pain. In the full text's between-group table, the 500 mg dose scored better than placebo on WOMAC pain at 30, 60 and 90 days and on WOMAC function at all three visits; the 250 mg dose differed from placebo on stiffness and function but not pain. No correction for multiple comparisons is described and no trial registration is reported. CRP changes were not statistically significant apart from a within-group change from baseline at 90 days in the 250 mg group, and ESR changes were not significant in any group. Liver enzymes and routine blood tests showed no changes suggesting toxicity. Unigen funded the trial; the second author is a Unigen employee.
  7. Arjmandi BH, Ormsbee LT, Elam ML, Campbell SC, Rahnama N, Payton ME, Brummel-Smith K, Daggy BP. A combination of Scutellaria baicalensis and Acacia catechu extracts for short-term symptomatic relief of joint discomfort associated with osteoarthritis of the knee. J Med Food. 2014;17(6):707-13. doi: 10.1089/jmf.2013.0010.PubMedUsed to support: Other product (UP446). Double-blind randomized trial in adults aged 40 to 90 with mild to moderate knee osteoarthritis (79 analyzed: 45 UP446, 34 naproxen) taking UP446 500 mg a day or naproxen 440 mg a day for 1 week, with no placebo group. Perceived pain fell over time in the UP446 group (p = .009), stiffness fell in both groups, and range of motion rose over time in the UP446 group; the abstract reports changes over time rather than a difference between the two products. Serum IL-6, CRP and hyaluronic acid did not change in either group, TNF-alpha rose significantly in both groups, and IL-1 beta was higher with UP446 than with naproxen at the end. The full text states that Unigen, Inc. funded the study.
  8. Levy RM, Khokhlov A, Kopenkin S, Bart B, Ermolova T, Kantemirova R, Mazurov V, Bell M, Caldron P, Pillai L, Burnett BP. Efficacy and safety of flavocoxid, a novel therapeutic, compared with naproxen: a randomized multicenter controlled trial in subjects with osteoarthritis of the knee. Adv Ther. 2010;27(10):731-42. doi: 10.1007/s12325-010-0064-z.PubMedUsed to support: Other product (flavocoxid, a baicalin and catechin blend). Randomized, multicenter, double-blind trial in 220 adults with moderate to severe knee osteoarthritis comparing flavocoxid 500 mg twice daily with naproxen 500 mg twice daily for 12 weeks, designed to show noninferiority, with no placebo group. WOMAC scores and a timed walk did not differ significantly between groups in the intent-to-treat analysis; the flavocoxid group had fewer upper digestive and edema adverse events. The first author is affiliated with Primus Pharmaceuticals.
  9. Morgan SL, Baggott JE, Moreland L, Desmond R, Kendrach AC. The safety of flavocoxid, a medical food, in the dietary management of knee osteoarthritis. J Med Food. 2009;12(5):1143-8. doi: 10.1089/jmf.2008.0244.PubMedUsed to support: Other product (flavocoxid). 12 week randomized, double-blind, placebo-controlled safety trial in 59 adults with knee osteoarthritis taking flavocoxid 250 mg twice daily or placebo. Adverse events, blood pressure and laboratory values did not differ between groups, except that upper respiratory adverse events were more frequent on placebo (35.4% vs 5.8%). No author reported a competing financial interest.
  10. Chalasani N, Vuppalanchi R, Navarro V, Fontana R, Bonkovsky H, Barnhart H, Kleiner DE, Hoofnagle JH. Acute liver injury due to flavocoxid (Limbrel), a medical food for osteoarthritis: a case series. Ann Intern Med. 2012;156(12):857-60, W297-300. doi: 10.7326/0003-4819-156-12-201206190-00006.PubMedUsed to support: Other product. US Drug-Induced Liver Injury Network case series: among 877 enrolled patients, 4 women aged 57 to 68 developed acute liver injury 1 to 3 months after starting flavocoxid, a prescription medical food blending baicalin (from Scutellaria baicalensis) and catechins (from Acacia catechu). All recovered within 3 to 12 weeks of stopping; causality was judged highly likely in 3 and possible in 1. It did not study black catechu on its own.
  11. National Institute of Diabetes and Digestive and Kidney Diseases. Flavocoxid. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. 2018;Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. Entry dated 2018 Jan 30. NCBI Bookshelf NBK548129..PubMedUsed to support: Other product. NIH LiverTox summary (as indexed in PubMed): flavocoxid is a medical food of plant-derived flavonoids used for chronic osteoarthritis and has been linked to minor serum enzyme elevations during therapy and to rare instances of clinically apparent liver injury.
  12. Curtis JR, Owensby JK, Xie F. Comparative safety of flavocoxid vs prescription NSAIDs among osteoarthritis patients. Osteoarthritis Cartilage. 2020;28(7):917-923. doi: 10.1016/j.joca.2020.03.017.PubMedUsed to support: Other product. US insurance claims study (2006 to 2017) of 3,337 new flavocoxid users and 6,674 new users of prescription NSAIDs, compared after 1:2 propensity score matching. Hospitalized liver injury occurred at 3.2 versus 2.4 per 1,000 person-years (adjusted hazard ratio 1.16, 95% CI 0.23 to 6.01) and hypersensitivity pneumonitis at 1.1 versus 0.0 per 1,000 person-years; the authors judged both rates low. The full text states that the study received no external funding and that Primus Pharmaceuticals provided an unrestricted educational grant to the University of Alabama at Birmingham; the authors declare no conflicts of interest related to the work.
  13. Kalman DS, Hewlings SJ. The Effects of Morus alba and Acacia catechu on Quality of Life and Overall Function in Adults with Osteoarthritis of the Knee. J Nutr Metab. 2017;2017:4893104. doi: 10.1155/2017/4893104.PubMedUsed to support: Randomized, double-blind trial in 135 adults with knee osteoarthritis comparing UP1306 400 mg a day, glucosamine hydrochloride 1,500 mg plus chondroitin sulfate 1,200 mg a day, and placebo for 12 weeks. WOMAC pain, stiffness and daily function, discomfort ratings, rescue medication use, range of motion and walking distance improved within all groups but did not differ between them; TNF-alpha did not change in any group. The change in urine CTX-II differed between UP1306 and placebo at 12 weeks (p = 0.029). No serious adverse events. Funded by Unigen Pharmaceuticals; registered ISRCTN15418623.
  14. Yimam M, Burnett BP, Brownell L, Jia Q. Clinical and Preclinical Cognitive Function Improvement after Oral Treatment of a Botanical Composition Composed of Extracts from Scutellaria baicalensis and Acacia catechu. Behav Neurol. 2016;2016:7240802. doi: 10.1155/2016/7240802.PubMedUsed to support: Other product (UP326, a Scutellaria baicalensis root and Acacia catechu heartwood blend). In aged rats, 7 and 34 mg/kg for 11 weeks reduced maze errors. In a 30 day trial in 83 healthy adults aged 35 to 65 (43 UP326, 40 placebo), the main group effect on reaction time was not significant (p = 0.1314); a group by week interaction (p = 0.05) showed faster responses in weeks 2 and 3. The methods give the dose as 300 mg a day; the abstract said 300 mg twice daily, and a 2017 corrigendum (Behav Neurol 2017:3493086, PMID 28729756) corrected the abstract to 300 mg per day. No registration is reported. Three of the four authors are Unigen employees.
  15. Krieger JM, Hagele AM, Mumford PW, De Gregorio D, Gaige CJ, Hoffman ER, Gross KN, Holley KF, Allen LE, Kerksick CM. Effects of Acacia catechu and Scutellaria baicalensis extract on cognitive function in a healthy adult population: a double-blind, randomized, placebo-controlled trial. Nutr Neurosci. 2025;28(8):975-986. doi: 10.1080/1028415X.2024.2442425.PubMedUsed to support: Other product (UP326, Unigen). Randomized, double-blind, placebo-controlled trial in 85 healthy adults (26 men, 59 women, average age 43) taking a product with 240 mg of Scutellaria baicalensis extract and 51 mg of Acacia catechu heartwood extract, or placebo, for 4 weeks. Cognitive scores improved over time in both groups with no difference between them; BDNF, CRP and safety blood markers did not differ, and no adverse events were reported. Registered ISRCTN16548309. All authors are at Lindenwood University; funding is not stated in the abstract.
  16. International Agency for Research on Cancer. IARC strengthens its findings on several carcinogenic personal habits and household exposures (Press Release No. 196). IARC press release. 2009;Press release No. 196, 2 November 2009. Accessed November 2026..SourceUsed to support: Not PubMed-indexed; official IARC (World Health Organization) press release. States that betel quid generally consists of areca nut, betel leaf, catechu and slaked lime, often with added tobacco; that carcinogenic nitrosamines derived from areca nut, the primary ingredient, form in chewers' saliva; and that IARC reaffirmed the Group 1 (carcinogenic to humans) classification of betel quid with or without tobacco and of areca nut. It does not give catechu a separate classification.