Assessment of Glycemic Index for Dried Saskatoon Berries and Powder in Healthy Subjects

NCT ID: NCT06928688

Last Updated: 2026-01-08

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 10 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-03-01
• Study Completion Date: 2025-11-20

Brief Summary

The glycemic index (GI) ranks carbohydrate-containing foods based on their effect on postprandial blood glucose levels. Foods or food products with lower GI values (55 or less) are absorbed more slowly, gradually increasing blood glucose and insulin levels. Fruits are believed to have a lower GI, making them potentially beneficial for individuals seeking to manage blood sugar levels. Previous studies from our and other groups suggest that Saskatoon berry (SB) is a potential functional food for glucose management. The glycemic index (GI) of dried SB powder and whole fruit remains undetermined, limiting our ability to make precise dietary recommendations. This study aims to evaluate the GI in both whole fruit and powder forms of SB. The determination of GI on SB products allows us to provide evidence-based guidance for healthcare providers when recommending SB as a functional food for glucose control.

Detailed Description

I. Research Objective: This study aims to evaluate the GI of Saskatoon berry powder and whole fruit in healthy individuals.

II. Methodology:

Study Design

• Type: Randomized, open-label study.
• Duration: Approximately 4 weeks for each participant.
• Setting: Clinical nutrition laboratory.

Participant Recruitment:

Following approval from the University of Manitoba Research Ethics Board, we will distribute recruitment materials across the university campus. Interested individuals may contact the research coordinator to express interest in participation.

Target enrollment: 10-20 participants

Eligibility Requirements:

• Individuals in good health (males and females)
• Between 18 and 74 years of age
• Body Mass Index (BMI) within the range of 18.5-29.9 kg/m²
• Free from diabetes, hyperlipidemia, and hypertension
• Must not be taking medications for diabetes, cholesterol, or blood pressure management.

Required Resources

• Saskatoon berry powder (Prairie Berry Inc.)
• Whole Saskatoon berries (Prairie Berry Inc.)
• Control substance: 25g glucose drink
• Glucose monitoring instruments
• Water (250ml) for powder administration Protocol Overview Visit #1: Initial Session: Research consent The research coordinator will conduct informed consent procedures at an agreed-upon location.
• Initial Assessment:

• Blood pressure measurement
• Heart rate monitoring
• Anthropometric measurements Visit #2: Primary Testing Session
• Preparation Guidelines:

• Fasting period: 10-14 hours overnight
• Session start: 9:00 AM
• Testing Protocol:

The participant will receive either Saskatoon berry powder (25g carbohydrate equivalent) with 250ml of water (consumption within 10 minutes), or whole Saskatoon berries (25g carbohydrate equivalent, consumption within 20 minutes) or glucose drink (25 g carbohydrate, consumption with in 10 min).

Blood glucose monitoring schedule:

Initial reading (0 min) 15 minutes post-consumption 30 minutes post-consumption 45 minutes post-consumption 60 minutes post-consumption 90 minutes post-consumption 120 minutes post-consumption Visit #3: Reference Food Assessment Participants will undergo an identical protocol with oral glucose drink (25g carbohydrate equivalent) 2-7 days following the initial assessment.

Important: A minimum 48-hour washout period is required between each test (control or berry preparation).

Analytical Methods The glycemic index will be determined through analysis of blood glucose area under curve (AUC), following established protocols (Brouns et al., 2005).

• GI will be calculated as the ratio of the incremental AUC (iAUC) for SB to the iAUC for glucose drink, multiplied by 100.
• Data will be presented as mean ± standard deviation.
• Paired t-tests or equivalent non-parametric tests will be used to compare iAUC between SB and glucose drink.
• A p-value < 0.05 will be considered statistically significant.

Conditions

Healthy Volunteers (HV)

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

SB powder

Volunteers drink 25 g of SB powder (25g carbohydrate equivalent) with 250ml water (consumption within 10 minutes)

Group Type: EXPERIMENTAL

Saskatoon berry powder

Intervention Type: DIETARY_SUPPLEMENT

After oral intake of SB powder, dried whole SB fruit or glucose drink, finger tip blood glucose will be measured 15, 30, 45, 60, 90 and 120 minutes after the consumption.

Dried whole SB fruit

Volunteers intake Dried whole SB fruit (25g carbohydrate equivalent) within 20 minutes. Participants have option to choose intake one or both SB products. One week interval is required between the interventions.

Group Type: EXPERIMENTAL

Saskatoon berry powder

Intervention Type: DIETARY_SUPPLEMENT

After oral intake of SB powder, dried whole SB fruit or glucose drink, finger tip blood glucose will be measured 15, 30, 45, 60, 90 and 120 minutes after the consumption.

Interventions

Saskatoon berry powder

After oral intake of SB powder, dried whole SB fruit or glucose drink, finger tip blood glucose will be measured 15, 30, 45, 60, 90 and 120 minutes after the consumption.

Intervention Type: DIETARY_SUPPLEMENT

Other Intervention Names

Dried whole Saskatoon berry; Glucose drink as control

Eligibility Criteria

Inclusion Criteria

• Individuals in good health (males and females)
• Between 18 and 74 years of age
• Signed informed consent

Exclusion Criteria

• Body Mass Index (BMI) >= 30 kg/m²
• Diabetes, hyperlipidemia, and hypertension
• Taking medications for diabetes, cholesterol, or blood pressure

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 74 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

University of Manitoba

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Locations

University of Manitoba

Winnipeg, Manitoba, Canada

Countries

Canada

References

Brouns F, Bjorck I, Frayn KN, Gibbs AL, Lang V, Slama G, Wolever TM. Glycaemic index methodology. Nutr Res Rev. 2005 Jun;18(1):145-71. doi: 10.1079/NRR2005100.

Reference Type: RESULT

PMID: 19079901 (View on PubMed)

Zhao R, Khafipour E, Sepehri S, Huang F, Beta T, Shen GX. Impact of Saskatoon berry powder on insulin resistance and relationship with intestinal microbiota in high fat-high sucrose diet-induced obese mice. J Nutr Biochem. 2019 Jul;69:130-138. doi: 10.1016/j.jnutbio.2019.03.023. Epub 2019 Apr 9.

Reference Type: RESULT

PMID: 31078906 (View on PubMed)

Other Identifiers

HS26810 (B2025:012)

Identifier Type: -

Identifier Source: org_study_id