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Kawakawa

Piper excelsum

Also calledRākau rongoā (Māori: medicinal plant)

In older monographsMacropiper excelsum

A shrub endemic to Aotearoa New Zealand and one of the most important plants of rongoā Māori, used for skin conditions, wounds, stomach and genitourinary complaints. Today it is widely drunk as a tea; small New Zealand studies have begun testing its effects on blood sugar and inflammation.

What it is used for

  • Used traditionally for diabetes. In a 6-person pilot, kawakawa tea (4 g leaves in 250 ml) lowered blood glucose and insulin after a high-sugar breakfast; in a follow-up 30-person crossover study only insulin was lower. These were single-dose studies in healthy people.1

  • Rongoā Māori applies kawakawa to a range of skin conditions.1,2

  • Wounds and cuts
    Traditional

    Used for wounds; Māori knowledge holds that leaves holed by the kawakawa looper caterpillar heal better.1,2

  • Traditionally used for genitourinary infections and complaints.1,2

  • Taken internally for gastrointestinal problems.2

How it is prepared

infusion

Dried leaves steeped in hot (75–80 °C) water as a tea.

Ramzan 2022 trial dose: 4 g dried leaves in 250 ml hot water, single dose.

Blood sugar and diabetes

Amounts are as recorded by the named source, not a recommendation.

Safety

Pregnancy
Insufficient data
Breastfeeding
Insufficient data
Children
No data.

Interactions with medicines

  • diabetes medicinesMinorTheoretical additive effect on blood glucose and insulin; not studied.
Interaction checker →

Toxicity

Rats given a commercial kawakawa tea for 28 days, at up to the equivalent of four cups a day for an adult woman, showed no adverse effects.

In the healing traditions

  • Pacific / Polynesian

    Kawakawa (rākau rongoā)

    In rongoā Māori taken internally for gastrointestinal and genitourinary problems and diabetes, and applied to skin conditions and wounds; leaves eaten by the kawakawa looper (whangawhanga, Cleora scriptaria) are prized as more healing.

  • Modern pharmacology

    Kawakawa tea

    Studied at the University of Auckland's Liggins Institute for effects on glucose metabolism and inflammatory microRNAs.

Active compounds

diayangambin and excelsin
lignans; diayangambin reported immunomodulatory and anti-inflammatory
myristicin and elemicin
phenylpropanoids; myristicin is anti-inflammatory in lab studies
piperine, dihydropiperlonguminine, pellitorine
amides; dihydropiperlonguminine increased glucose uptake in gut cells
vitexin
flavone glycoside with reported antidiabetic activity

History

Kawakawa is endemic to Aotearoa New Zealand and of cultural and medicinal importance to Māori. It is now widely drunk as a tea and added to 'functional' food products.

Sources

  1. 1.Ramzan F et al. Acute effects of kawakawa (Piper excelsum) intake on postprandial glycemic and insulinaemic response in a healthy population. Nutrients 2022;14:1638
  2. 2.O'Connor C et al. Kawakawa and the hungry little caterpillars: the kawakawa looper Cleora scriptaria causes unique plant responses in kawakawa leaves. Preprint 2024 (abstract)
  3. 3.Jayaprakash R et al. Human metabolism and excretion of kawakawa (Piper excelsum) leaf chemicals. Mol Nutr Food Res 2024 (abstract)
  4. 4.Tautuiaki S et al. Anti-inflammatory effects of kawakawa (Piper excelsum): an integrative mRNA–miRNA approach. Food Sci Nutr 2024 (abstract)
  5. 5.GBIF: Piper excelsum G.Forst. (IUCN Least Concern; backbone synonym of Macropiper excelsum)

Reference, not prescription. Nothing here is medical advice. Herbs can interact with medicines and be dangerous in pregnancy; tell your doctor or pharmacist about anything you take.