New Zealand: Kawakawa tea consumption (4 g/250 mL hot water) may modulate postprandial glucose metabolism, claims a study published in the journal Nutrients.
Piper excelsum (kawakawa) is a shrub endemic to Aotearoa, New Zealand, of cultural and medicinal importance to Māori. Its leaves and fruits are often consumed. These tissues contain several compounds that have been shown to be biologically active and which may support its putative health-promoting effects.

Against the above background, Farha Ramzan, Liggins Institute, The University of Auckland, Auckland, New Zealand, and colleagues aimed to investigate whether kawakawa tea can modulate postprandial glucose metabolism in a pilot three-arm randomized crossover study.
The researchers assessed the bioavailability of kawakawa tea (BOKA-T) in six male participants with each arm having an acute intervention of kawakawa tea (4 g/250 mL water; 1 g/250 mL water; water) and a follow-up two-arm randomized crossover study to assess the impact of acute kawakawa tea ingestion on postprandial glucose metabolism in healthy human volunteers (TOAST) (4 g/250 mL water; and water; n = 30 (15 male and 15 female)).
Prior to consuming a high-glycemic breakfast, the participants consumed 250 mL of kawakawa tea or water control within each study. Measurements of pre-and postprandial plasma glucose and insulin concentrations were done, and to measure insulin sensitivity, the Matsuda index was calculated.
Based on the study, the researchers reported the following:
In the BOKA-T study, lower plasma glucose (p < 0.01) and insulin (p < 0.01) concentrations at 60 min were observed after consumption of a high-dose kawakawa tea in comparison to low-dose or water.
In the TOAST study, only plasma insulin was lower at 60 min in the high-dose kawakawa group compared to the control group.
Both studies showed a trend towards higher insulin sensitivity in the high-dose kawakawa group compared to water only.
To conclude, acute intake of kawakawa tea attenuated insulin response to a subsequent high-glycemic meal. In the BOKA-T study, a lower increase in postprandial plasma glucose with the high dose of kawakawa intake was observed compared to the control, in the TOAST study no similar effects were observed.
"Our preliminary findings suggest that kawakawa consumption may improve insulin response and sensitivity," the researchers wrote in their study. "However, further investigations with longer-term interventions are needed to assess any physiological or clinical significance."
Reference:
Ramzan F, Jayaprakash R, Pook C, Foster M, Miles-Chan JL, Mithen R. Acute Effects of Kawakawa (Piper excelsum) Intake on Postprandial Glycemic and Insulinaemic Response in a Healthy Population. Nutrients. 2022 Apr 14;14(8):1638. doi: 10.3390/nu14081638. PMID: 35458200; PMCID: PMC9032225.