Raspberry Leaf Tea‘s Impact on Insulin Response to Sucrose: A New Study
A recent study published in Nutrients (2025) by Alkhudaydi and Spencer investigated the effects of raspberry leaf tea on postprandial glucose and insulin responses in healthy adults. The research revealed a significant reduction in insulin surges following the consumption of sucrose (table sugar) when paired wiht raspberry leaf tea, but no such effect was observed with glucose alone.
The trial involved 22 participants, 20 of whom completed all study visits.Participants consumed either sucrose or glucose, with or without concurrent consumption of raspberry leaf tea brewed for five minutes – a readiness standardized to deliver approximately 50 mg of total polyphenols, primarily ellagitannins and ellagic acid, per serving. blood samples were collected at baseline and at 15, 30, 60, 90, and 120-minute intervals post-consumption, with glucose analyzed using the hexokinase method and insulin via automated immunoassay.
Results demonstrated that when sucrose was consumed, raspberry leaf tea substantially lowered both glucose and insulin responses. Specifically, mean glucose levels decreased by 1.19 mmol/L at 15 minutes (p = 0.001) and 2.03 mmol/L at 30 minutes (p = 0.0004). Insulin levels were suppressed by 113.9 pmol/L at 15 minutes (p = 0.019), 161.8 pmol/L at 30 minutes (p = 0.0008), and 139.4 pmol/L at 60 minutes (p = 0.025).
Notably,no statistically significant differences in blood glucose or insulin were found between the tea and control conditions when participants consumed glucose. Both glucose and insulin peaked at 30 minutes and returned to baseline levels by 120 minutes, nonetheless of tea intake.This finding indicates the beneficial effects of raspberry leaf tea are specific to disaccharide metabolism – the breakdown of sugars like sucrose - rather than monosaccharide absorption (like glucose).
The researchers hypothesize that the tea’s effect stems from its inhibition of carbohydrate-digesting enzymes, such as α-glucosidase and sucrase, likely due to the presence of ellagic acid and other polyphenols. Importantly, participants did not report any gastrointestinal side effects, suggesting raspberry leaf tea could be a well-tolerated dietary approach to managing glycemic responses.
The study acknowledges several limitations, including its acute design (single-dose), lack of blinding and placebo control, small and homogeneous sample size, and short duration. These factors limit the generalizability of the findings and preclude conclusions regarding long-term effects. The authors recommend larger, longer-term studies in more diverse populations, including individuals with impaired glucose control, to further investigate the potential of raspberry leaf tea as a natural modulator of postprandial glycemia.
