Establishing the Glycaemic Index of Fruit Drinks Using Different Measurement Methodologies

Study to Examine Glycaemic Responses to the Ingestion of Fruit Juices and Smoothies Using Different Measurement Methodologies.

Glycaemic responses to carbohydrates ingested as fruit sugars may vary depending on factors inherent to the fruit and the type of sugar. The aim of this project is to investigate the glycaemic responses to a range of commercially available fruit drinks and to establish the glycaemic index for each product relative to a glucose reference. Differences in recorded responses could also be influenced by the sample type (capillary blood vs interstitial fluid) and participant characteristics. Participants will ingest 8 test drinks including 5 different fruit drinks (OJ, AJ, S&B, ENERGISE, BLUE), each matched for carbohydrate to the glucose reference (CONTROL) which will be sampled two times, an additional sample of one of the smoothies (S&B) will also be replicated. Fingerstick capillary blood sampling alongside dual sited continuous glucose monitors (CGM) will measure glucose and lactate concentrations, subjective appetite sensations will also be recorded. The tests will follow best practice guidelines for glycaemic index testing. These data will provide insight into how differing formulations can alter the glycaemic responses to fruit drinks, and whether sampling technique can affect the interpretations of measurement.

Study Overview

• Status: Completed
• Conditions: Glycaemic Index; Glycaemic Response Measurements
• Intervention / Treatment: Other: Fruit drink

• Study Type: Interventional
• Enrollment (Actual): 11
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Bath, United Kingdom, BA2 7AY
    • Department for Health, University of Bath

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Age: 18-65 years
• Body mass index 18-30 kg/m2

Exclusion Criteria:

• diagnosis of any form of diabetes
• intolerances or allergies to any of the study procedures (e.g. fructose/inulin intolerance)
• Fructose malabsorption
• Inborn errors of fructose metabolism (e.g. fructokinase deficiency, aldolase B deficiency, fructose-1,6-bisphosphatase deficiency)
• pregnant or lactating
• any condition that could introduce bias to the study (e.g. diagnoses of lipid disorders, including cardiovascular disease, or therapies that alter lipid or glucose metabolism, such as statins or niacin).

Study Plan

How is the study designed?

Design Details

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

Number of Arms

8

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: CONTROL; 50 g glucose (55 g dextrose powder accounting for hydration) plus 641 mL water	Other: Fruit drink; Commercially available fruit drinks or smoothies
Active Comparator: REPLICATE CONTROL; 50 g glucose (55 g dextrose powder accounting for hydration) plus 641 mL water	Other: Fruit drink; Commercially available fruit drinks or smoothies
Experimental: S&B; 417 mL of commercially available "Strawberries & Bananas" fruit smoothie providing 50 g carbohydrate [strawberries (31%), apples, bananas (22%), white grapes, oranges, blackcurrants]. Plus 224 mL water to standardise volume	Other: Fruit drink; Commercially available fruit drinks or smoothies
Experimental: REPLICATE S&B; 417 mL of commercially available "Strawberries & Bananas" fruit smoothie providing 50 g carbohydrate [strawberries (31%), apples, bananas (22%), white grapes, oranges, blackcurrants]. Plus 224 mL water to standardise volume	Other: Fruit drink; Commercially available fruit drinks or smoothies
Experimental: OJ; 641 mL of commercially available "Smooth Orange Juice" providing 50 g of carbohydrate [100% oranges]	Other: Fruit drink; Commercially available fruit drinks or smoothies
Experimental: AJ; 455 mL commercially available "Apple Juice" providing 50 g of carbohydrate [apples, ascorbic acid]. Plus 186 mL water to standardise volume	Other: Fruit drink; Commercially available fruit drinks or smoothies
Experimental: ENERGISE; 417 mL of commercially available "Energise Super Smoothie" providing 50 g carbohydrate [apples (50%), red grapes, bananas, strawberries (10%), blackcurrants, sour cherries (3.3%), pressed beetroot, flax seeds (0.56%), guarana infusion (0.01%), vitamins B1, B2, B3, B6, C & E]. Plus 224 mL water to standardise volume	Other: Fruit drink; Commercially available fruit drinks or smoothies
Experimental: BLUE; 521 mL of commercially available "Bolt from the Blue" juice drink providing 50 g carbohydrate [apple (66%), coconut water (18%), white grapes, white guava (5.2%), passion fruit, lime (0.87%), spirulina extract (0.81%) vitamins B1, B2, B3, B6, C & E]. Plus 120 mL water to standardise volume	Other: Fruit drink; Commercially available fruit drinks or smoothies

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycaemic indices for 5 test drinks measured using capillary blood samples	Glycaemic indices [2-hour incremental area under the glucose curve (mmol/L-1x120 minutes) for each of the 5 test drinks relative to mean value of control conditions (CONTROL, REPLICATE CONTROL), expressed as a percentage] in capillary blood samples	120 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycaemic index of all conditions with capillary blood samples vs CGM	The difference in glycaemic index [2-hour incremental area under the glucose curve (mmol/L-1x120 minutes) for 5 test drinks relative to mean control (CONTROL, REPLICATE CONTROL), expressed as a percentage] in capillary blood samples versus continuous glucose monitors.	120 minutes

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Comparisons between conditions in glucose concentration in capillary samples	Comparison of blood glucose concentration 2-hour incremental area under the curve (iAUC) min.mmol/L between test conditions	120 minutes
Comparisons between conditions in glucose concentration in capillary samples	Comparison of postprandial peak concentration mmol/L of blood glucose between test conditions (Cmax)	120 minutes
Comparisons between conditions in glucose concentration in capillary samples	Comparison of time to peak blood glucose concentration in minutes (Tmax) between test conditions	120 minutes
Comparisons between conditions in glucose concentration in capillary samples	Comparison of blood glucose concentration mmol/L at 2 hours between test conditions	120 minutes
Comparisons between conditions in glucose concentration with CGM	Comparison of glucose concentration 2-hour incremental area under the curve (iAUC) min.mmol/L between test conditions	120 minutes
Comparisons between conditions in glucose concentration with CGM	Comparison of postprandial peak concentration mmol/L of glucose between test conditions (Cmax)	120 minutes
Comparisons between conditions in glucose concentration with CGM	Comparison of time to peak glucose concentration in minutes (Tmax) between test conditions	120 minutes
Comparisons between conditions in glucose concentration with CGM	Comparison of glucose concentration mmol/L at 2 hours between test conditions	120 minutes
Comparisons between conditions in lactate concentration in capillary samples	Comparison of blood lactate concentration 2-hour incremental area under the curve (iAUC) min.mmol/L between test conditions	120 minutes
Comparisons between conditions in lactate concentration in capillary samples	Comparison of postprandial peak concentration mmol/L of blood lactate between test conditions (Cmax)	120 minutes
Comparisons between conditions in lactate concentration in capillary samples	Comparison of time to peak blood lactate concentration in minutes (Tmax) between test conditions	120 minutes
Comparisons between conditions in lactate concentration in capillary samples	Comparison of blood lactate concentration mmol/L at 2 hours between test conditions	120 minutes
Comparisons between conditions of appetite ratings	Comparison of subjective appetite sensations assessed with visual analogue scales (2-hour area under the curve min.mmVAS)	120 minutes
Comparisons between individuals	Comparison of Postprandial lactate concentration min.mmol/L between individuals 2-hour incremental area under curve (iAUC)	120 minutes
Comparisons between individuals	Comparison of Postprandial glucose concentration min.mmol/L between individuals 2-hour incremental area under curve (iAUC)	120 minutes
Comparisons between individuals	Comparison of Appetite rating responses min.mmVAS between individuals 2-hour area under curve (AUC)	120 minutes
Comparisons within individuals	Comparison within individuals of interstitial glucose concentrations measurements from continuous glucose monitors on left and right arms.	120 minutes

Collaborators and Investigators

• Sponsor: University of Bath

Publications and helpful links

General Publications

• Gonzalez JT. Are all sugars equal? Role of the food source in physiological responses to sugars with an emphasis on fruit and fruit juice. Eur J Nutr. 2024 Aug;63(5):1435-1451. doi: 10.1007/s00394-024-03365-3. Epub 2024 Mar 16.

Study record dates

Study Major Dates

• Study Start (Actual): March 13, 2025
• Primary Completion (Actual): July 9, 2025
• Study Completion (Actual): July 9, 2025

Study Registration Dates

• First Submitted: February 28, 2025
• First Submitted That Met QC Criteria: March 20, 2025
• First Posted (Actual): March 27, 2025

Study Record Updates

• Last Update Posted (Actual): May 11, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Glycaemic Index; Fruit Drinks
• Other Study ID Numbers: 7134-9931

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified data will be made available open access on the University of Bath Research Data Archive (RDA) at the point of publication in a peer-reviewed journal.
• IPD Sharing Time Frame: These will become available at the point of publication permanently
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No