The Effects of Raspberry Leaf Tea on Blood Glucose Control (RLT)

The Effects of Raspberry Leaf Tea on Blood Glucose Control in Healthy Adults

The aim of the present clinical trial is to assess how raspberry leaf polyphenols impact on postprandial glucose and insulin levels in healthy individuals consuming sucrose.

The questions the project will address:

• Do raspberry leaf polyphenols lower sucrose-induced increases in plasma glucose in humans?

• Do these polyphenols mediate these effects by inhibiting digestion of sucrose or the absorption of glucose.

  20 healthy adults will be recruited between the ages of 18-65 years who are non-smokers and not taking certain types of medication (e.g., drugs from a GP for high blood pressure, high blood fats, inflammatory conditions, and depression) or dietary supplements (e.g., cholesterol-lowering spreads, fish oil, probiotics, prebiotics, and natural laxatives), antibiotics in the last three months or if they used any drugs or supplements that could affect their blood glucose or lipid metabolism. No abnormal results for liver function tests, renal function tests, and lipid profile tests. If they have food allergies or consume more than 14 units of alcohol per week (i.e., to help they calculate a alcohol intake, one standard glass of wine (175 ml) or one pint of regular lager is equivalent to just over two units of alcohol), frequently travel for work or are participating in another intervention study, they will not be able to participate. Women who are pregnant or lactating or planning a pregnancy in the next six months will also not be able to take part, not use herbal medicines for at least the previous three months, not be on a weight loss program six months before screening, not involved in clinical trials six months before the screening, and not having severe cardiac, hepatic, or renal function impairment. Not Sufferers of chronic illnesses, not Individuals with food allergies, not people with coeliac disease.

They will be asked to attend a four-study visit after an eight-hour overnight fast. Volunteers will be asked to consume 50 g of carbohydrate powder (sucrose and glucose) with or without 10 g of raspberry leaf tea, which will be dissolved in 300 mL of warm water during four visits (every month). Blood samples will be taken at intervals for a period of two hours after the consumption of raspberry leaf or control. Blood glucose and insulin levels will be tested 15 minutes before, at 15,30,60,90, and 120 minutes after carbohydrate intake.

Study Overview

• Status: Recruiting
• Conditions: Type II Diabetes
• Intervention / Treatment: Dietary supplement: Raspberry leaf tea

Detailed Description

The volunteer inclusion criteria are: (Fasting blood glucose in the range < 5.5 mmol/l (at day 0); A signed consent form; Age 18-65 years; Body mass index ≤ 34.9 kg/m2; Non-smoking; No pregnancy/lactation; No use of herbal medicines for at least the previous three months; Not on a weight loss program six months before screening; Not involved in clinical trial six months before screening; Not had severe cardiac, hepatic, or renal function impairment).

The volunteer exclusion criteria are: (Smoking, Pregnancy/lactation; Use of herbal medicines for at least the previous three months; Involved in a weight loss program six months before screening; Involved in clinical trial six months before the screening; Had severe cardiac, hepatic, or renal function impairment; Sufferers of chronic illnesses; Individuals with food allergies; People with prediabetes or diabetes; People with coeliac disease)

If all subjects are generally healthy, as demonstrated by their medical history and laboratory tests, including fasting blood sugar and insulin levels, as well as HOMA-IR, liver function tests (alanine transaminase, alkaline phosphatase, total bilirubin, and gamma-GT), renal function tests (uric acid and creatinine), and lipid profile tests (total cholesterol, Triglycerides). They will be asked to attend a four-study visit after an eight-hour overnight fast. Volunteers will be asked to consume 50 g of carbohydrate powder (sucrose and glucose) with or without 10 g of raspberry leaf tea, which will be dissolved in 300 mL of warm water during four visits (every month). Blood samples will be taken at intervals for a period of two hours after the consumption of raspberry leaf or control. Blood glucose and insulin levels will be tested 15 minutes before, at 15,30,60,90, and 120 minutes after carbohydrate intake.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jeremy Spencer, PhD; Phone Number: 01183788724; Email: j.p.e.spencer@reading.ac.uk

Study Locations

• United Kingdom
  • Berkshire
    • Reading, Berkshire, United Kingdom, RG6 5SG
      • Recruiting
      • Hugh Sinclair Unit of Human Nutrition, University of Reading

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

The volunteer inclusion criteria are:

• Fasting blood glucose in the range < 5.5 mmol/l (at day 0)
• A signed consent forms.
• Age 18-65 years
• Body mass index ≤ 34.9 kg/m2
• Non-smoking
• No pregnancy/lactation
• No use of herbal medicines for at least the previous three months
• Not on a weight loss program six months before screening
• Not involved in clinical trial six months before screening
• Not had severe cardiac, hepatic, or renal function impairment

The volunteer exclusion criteria are:

• Smoking
• Pregnancy/lactation
• Use of herbal medicines for at least the previous three months
• Involved in a weight loss program six months before screening.
• Involved in clinical trial six months before the screening.
• Had severe cardiac, hepatic, or renal function impairment.
• Sufferers of chronic illnesses
• Individuals with food allergies
• People with prediabetes or diabetes
• People with coeliac disease

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: sucrose + raspberry leaf tea; Volunteers will be asked to consume 50 g of sucrose with 10 g of raspberry leaf tea dissolved in 300 mL of warm water.	Dietary supplement: Raspberry leaf tea; 10 g of raspberry leaf tea
Experimental: glucose + raspberry leaf tea; Volunteers will be asked to consume 50 g of glucose with10 g of raspberry leaf tea dissolved in 300 mL of warm water.	Dietary supplement: Raspberry leaf tea; 10 g of raspberry leaf tea
Active Comparator: sucrose; Volunteers will be asked to consume 50 g of sucrose without 10 g of raspberry leaf tea	Dietary supplement: Raspberry leaf tea; 10 g of raspberry leaf tea
Active Comparator: glucose; Volunteers will be asked to consume 50 g of glucose without 10 g of raspberry leaf tea	Dietary supplement: Raspberry leaf tea; 10 g of raspberry leaf tea

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Blood Glucose	Area under the plasma glucose curve 0-120 minutes	Two hours

Collaborators and Investigators

• Sponsor: University of Reading
• Investigators: Principal Investigator: Jeremy Spencer, PhD, University of Reading

Study record dates

Study Major Dates

• Study Start (Actual): December 18, 2023
• Primary Completion (Estimated): December 23, 2024
• Study Completion (Estimated): December 23, 2024

Study Registration Dates

• First Submitted: April 19, 2024
• First Submitted That Met QC Criteria: April 24, 2024
• First Posted (Actual): April 26, 2024

Study Record Updates

• Last Update Posted (Actual): April 26, 2024
• Last Update Submitted That Met QC Criteria: April 24, 2024
• Last Verified: April 1, 2024

More Information

Terms related to this study

• Keywords: polyphenols; glucose
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Endocrine System Diseases; Diabetes Mellitus; Diabetes Mellitus, Type 2
• Other Study ID Numbers: UREC: 23_15-Raspberry Leaf Tea

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No