Smoothies and Blood Sugars

Examining the Blood Sugar Response to Fruit Smoothie Consumption

Glycaemic responses to fruit smoothies may depend on the food matrix (e.g., degree of processing and physical structure), ingestion rate, dose ingested and fibre content. Furthermore, the method of sampling could alter inferences. The aim of this project is to characterise how these factors affect the glycaemic response to a commercially available fruit smoothie. Participants will ingest 7 different test drinks in a randomised, crossover design with fingerstick capillary blood sampling alongside continuous glucose monitors. Test drinks will include a glucose reference (CONTROL), the commercial product matched for carbohydrate to CONTROL (PRODUCT), equivalent carbohydrate ingested as whole fruits (WHOLE), equivalent carbohydrate ingested as blended fruits (WHOLE), equivalent carbohydrate as the commercial product ingested slowly (SLOW), equivalent carbohydrate as the commercial product ingested with additional fibre (FIBRE), and the commercial product ingested in a dose typically bought (DOSE). These data will provide insight into how the food matrix and different patterns of ingestion can alter the glycaemic response to a fruit smoothie, and how the measurement method may alter interpretations.

Study Overview

• Status: Completed
• Conditions: Metabolic Disturbance
• Intervention / Treatment: Other: Food

• Study Type: Interventional
• Enrollment (Actual): 15
• 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

7

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Control; 50 g glucose (55 g dextrose powder accounting for hydration) plus 417 mL water	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies
Experimental: Product; 417 mL of commercially available "Mango & Passion fruit" fruit smoothie providing 50 g carbohydrate	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies
Experimental: Whole; Apples (51%), Mango (16%), Banana (16%), Orange (12%), Passionfruit (3%), Peach (2%), Lime (0.4%; recipe matched to PRODUCT) eaten as whole fruit with added water as needed to match volume.	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies
Experimental: Blend; Apples (51%), Mango (16%), Banana (16%), Orange (12%), Passionfruit (3%), Peach (2%), Lime (0.4%; recipe matched to PRODUCT) eaten as blended fruit with added water as needed to match volume.	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies
Experimental: Slow; 417 mL of commercially available "Mango and Passionfruit" fruit smoothie providing 50 g carbohydrate ingested slowly over 25-35 mins.	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies
Experimental: Fibre; 417 mL of commercially available "Mango and Passionfruit" fruit smoothie providing 50 g carbohydrate with 6 g of added inulin.	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies
Experimental: Dose; 250 mL of commercially available "Mango and Passionfruit" fruit smoothie providing 30 g carbohydrate.	Other: Food; Fruit ingested in whole form or as either commercially available, or home-made smoothies

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycaemic index of product with capillary vs CGM	The difference in glycaemic index [2-hour incremental area under the curve (mmol/L-1x120 min) for PRODUCT relative to CONTROL expressed as a percentage] in capillary blood samples versus continuous glucose monitors.	120 min

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycaemic index of all conditions with capillary vs CGM	The difference in glycaemic index [2-hour incremental area under the curve (mmol/L-1x120 min) for all other conditions (WHOLE, BLEND, SLOW, FIBRE, DOSE) relative to CONTROL expressed as a percentage] in capillary blood samples versus continuous glucose monitors.	120 min

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Condition-by-sampling interaction	The effect of condition-by-blood sampling (capillary vs continuous glucose monitor) interaction for the 2-hour incremental area under the curve for all conditions.	120 min
GI of products in capillary samples	Comparisons between conditions for the 2-hour incremental area under the curve relative to CONTROL using capillary blood glucose.	120 min
GI of products in continuous glucose monitors	Comparisons between conditions for the 2-hour incremental area under the curve relative to CONTROL using continuous glucose monitors.	120 min
Peak glucose capillary vs CGM	The condition-by-blood sampling interaction for the postprandial peak glucose concentrations (mmol/L)	120 min
Time to peak glucose capillary vs CGM	The condition-by-blood sampling interaction for the time to peak glucose concentrations (min)	120 min

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 20, 2024
• Primary Completion (Actual): August 30, 2024
• Study Completion (Actual): August 30, 2024

Study Registration Dates

• First Submitted: March 20, 2024
• First Submitted That Met QC Criteria: March 20, 2024
• First Posted (Actual): March 27, 2024

Study Record Updates

• Last Update Posted (Actual): September 19, 2024
• Last Update Submitted That Met QC Criteria: September 12, 2024
• Last Verified: September 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: 3085-4215

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