Saskatoon Berry on Metabolism and Gut Microbiota in Healthy Subjects

Pilot Study on the Effects of Saskatoon Berry on Glucose Metabolism, Insulin Resistance and Gut Microbiota in Healthy Human Subjects

Diabetes becomes epidemic in worldwide countries. Nine out of ten diabetic patients are type 2 diabetes (T2D). T2D is characterized by insulin resistance and obesity. Uncontrolled diabetes leads to serious consequences including heart attack, stroke, chronic renal failure, liver failure, blindness and low limb amputation. Most of hypoglycemic medications have side effects. Natural foods or nutraceuticals with hypoglycemic potential are expected to provide a safer management for diabetic patients. Saskatoon berry is a popular fruit in Canadian Prairie and Northern states in USA. Our recent studies demonstrated Saskatoon berry powder (SBp) attenuated hyperglycemia, hyperlipidemia, insulin resistance, inflammation, liver steatosis and gut dysbiosis in diet-induced insulin resistant mice, a model for T2D. The results in antidiabetic activities of SBp have been supported by other groups in high fat fed rats. The combination of findings suggest that Saskatoon berry is good candidate of prebiotic functional food as a supplemental remedy for reducing insulin resistance, metabolic syndrome and preventing or managing T2D. The effect of Saskatoon berry and its products on metabolic disorders have not been studied in human subjects. We propose to examine the effect of oral administration of freeze-dried Saskatoon berry on glucose metabolism, insulin resistance and gut microbiota in healthy adults in a pilot trial.

Subject recruitment: Healthy subjects (males and females, 18-75 years of age) in Winnipeg, who are voluntarily signing an informed consent approved by Research Ethics Board in University of Manitoba, will be eligible to the study. Exclusion criteria include: 1) candidates have a history of myocardial infarction, stroke, hypertension, diabetes, hyperlipidemia, chronic kidney disease; 2) participants are taking hypoglycemic, anti-hypertensives, lipid lowering medications or antibiotics within a month. Dietary product: Freeze dried Saskatoon berry have been obtained from Prairie Berries Inc. The berries were freshly frozen and no any supplementation was added to the dried berry. The product has been processed by certified facilities and the batch of dried berry has passed pathogen analysis. Regimen: Participants (n=20) will orally administrate 30 g/day of freeze dried Saskatoon berry during breakfast for 10 weeks. Scheduled visits: Visit 1: Consent and enrollment. A questionnaire for domestic questionnaire including dietary intake and physical activity will be filled. Measurements of body weight, height and blood pressure will be taken during the visit. Visit 2 (<1 week from the visit 1 and before the start of berry administration): 75 g oral glucose tolerance test (OGTT) after an overnight fasting. Insulin, liver enzymes (alanine transaminase or ALT, aspartate transaminase or AST), creatinine, lipid profile and inflammation markers (e. x. tumor necrosis factor-alpha or TNF-alpha) will be measured as baseline. Participants will be provided with sealed packages of dried Saskatoon berry and instruction of the administration. Insulin and lipid profile will be tested in blood samples withdrawn at fast glucose for OGTT. Visit 3 (at 5 weeks after the start of administration of Saskatoon berry): Participants will be asked to provide feedback on general well-being and the intake of Saskatoon berry. Body weight, blood pressure and heart rate will be measured and recorded. Visit 4 (at 10 weeks after the start of the dietary regimen): Participants will be asked to collect stool sample with the collection kit within 1 week before the visit and bring it to the visit. They will also be asked to have an overnight fasting the night before visit. They will receive an OGTT. Blood samples for insulin, liver enzymes, creatinine, lipid profile and inflammation markers will be collected from each participant. During the visit, body weight, blood pressure and heart rate of participants will be taken. Questionnaires on participants' dietary intake, physical activity and feedback to the study will be completed. Participants will receive a $50 honorarium gift card for their participation. Sample collection and analyses: OGTT, ALT, AST, creatinine and lipid profile will be analyzed in Clinical Chemistry in Health Science Centre, Winnipeg. Inflammation mediators will be analyzed in the Dr. G. Shen's laboratory. Homeostatic model assessment-insulin resistance or homeostatic model assessment for insulin resistance (HOMA-IR) will be calculated based on fasting plasma glucose and insulin. Stool samples will be aliquoted and stored under -80°C before submission. Microbiome analysis will be conducted in Integrate Microbiome Resource at Dalhousie University.

Healthy subject (n=20) will be enrolled in a single group for oral administration of dried Saskatoon berry as snack.

3 day food intake and the type in gram, frequency in time/day and length of physical activities index in artificial score (score scale 0-3, high means more activity)

Inclusion Criteria: Healthy subjects living in Winnipeg. Willingness to sign an informed consent. Exclusion Criteria: 1. History of myocardial infarction, stroke, hypertension, diabetes, hyperlipidemia, chronic kidney disease. 2) Participants are taking hypoglycemic, anti-hypertensives, lipid lowering medications or antibiotics within a 1 month.

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.

Huang F, Zhao R, Xia M, Shen GX. Impact of Cyanidin-3-Glucoside on Gut Microbiota and Relationship with Metabolism and Inflammation in High Fat-High Sucrose Diet-Induced Insulin Resistant Mice. Microorganisms. 2020 Aug 14;8(8):1238. doi: 10.3390/microorganisms8081238.

du Preez R, Wanyonyi S, Mouatt P, Panchal SK, Brown L. Saskatoon Berry Amelanchier alnifolia Regulates Glucose Metabolism and Improves Cardiovascular and Liver Signs of Diet-Induced Metabolic Syndrome in Rats. Nutrients. 2020 Mar 27;12(4):931. doi: 10.3390/nu12040931.