Effects of Barley on Glucose Control

Lifestyle modifications that include a diet high in fibre may lower the risk of developing type 2 diabetes (CDA, 2013). In this context, the presence of soluble dietary fibre in carbohydrate rich foods has been widely recognized for its effect on post-prandial glucose response (PPGR). Among these, oat and barley derived β-glucan have received tremendous attention for their biological effects, including their ability to reduce PPGR in a wide variety of food matrices (Poppitt et al, 2007). A health claim for PPGR would increase market demand for food grade barley, and help those who want to limit the rise in blood sugar after a meal choose products to meet their goals, but there are several gaps in the literature that need to be filled before a submission to Health Canada can be successful: 1) test foods in appropriate serving sizes; 2) test both the glucose and insulin response; 3) include a reference product that matches in total fibre, macronutrient, and energy profile; 4) perform dose response. The proposed study design will address all of these gaps in the current literature and take into consideration Health Canada's guidance document for health claims related to the reduction in PPGR, which sets out the criteria by which the validity of such claims will be assessed.

Hypothesis:

Barley β-glucan will reduce the PPGR in healthy participants in a dose dependent manner.

Specific objectives:

1. To determine the minimum and most effective dose of barley β-glucan in waffles on PPGR and insulin response in a cross-over, randomized, controlled clinical trial.
2. To assess the effect of barley β-glucan in waffles on appetite-related sensations using visual analog scales.
3. To demonstrate whether the test and reference products were liked or disliked similarly by participants.
4. To assess any gastrointestinal side effects from eating the test products

A double-blind, randomized, controlled, cross-over study designed to examine the PPGR to barley β-glucan will be conducted at the I.H. Asper Clinical Research Institute in Winnipeg, Manitoba. A total of 24 healthy volunteers will participate in the trial. Eligible participants who have provided consent will be asked to attend 5 clinic visits in a fasted state. At each visit hey will be given 1 set of waffles to eat that contains either 0g, 2g, 4g, or 6g of barley β-glucan, 7 finger pokes to collect capillary blood, 5 questionnaires about their appetite and a questionnaire about the acceptability of the quick bread. Each visit will last approximately 2.5h and be separated by 3-14 days.

Eligibility Criteria:
Inclusion Criteria:

1. Generally healthy male or female, between the age of 18-40 years;
2. Body mass index (BMI) 18.5-30.0 kg/m2;
3. Habitually consume breakfast, lunch and dinner in the morning, mid-day and evening, respectively;
4. Willing to provide informed consent;
5. Willing/able to comply with the requirements of the study.

Exclusion Criteria:

1. Pregnant or lactating;
2. Medical history of diabetes mellitus, fasting plasma glucose ≥7.0 mmol/L, HbA1c ≥6.0%, or use of insulin or oral medication to control blood sugar;
3. Medical history of cardiovascular disease;
4. Systolic blood pressure \>140 mm Hg or diastolic blood pressure \>90 mm Hg;
5. Fasting plasma total cholesterol \>7.8 mmol/L;
6. Fasting plasma HDL \<0.9 mmol/L;
7. Fasting plasma LDL \>5.0 mmol/L;
8. Fasting plasma triglycerides \>2.3 mmol/L;
9. Major surgery within the last 3 months;
10. Medical history of inflammatory disease (ie. Systemic lupus erythematosis, rheumatoid arthritis, psoriasis) or use of any corticosteroid medications within 3 months;
11. Medical history of liver disease or liver dysfunction (defined as plasma AST or ALT ≥1.5 times the upper limit of normal (ULN));
12. Medical history of kidney disease or kidney dysfunction (defined as blood urea nitrogen and creatinine ≥ 1.8 times the ULN));
13. Presence of a gastrointestinal disorder, daily use of any stomach acid-lowering medications or laxatives (including fibre supplements) within the past month or antibiotic use with the past 6 weeks;
14. Active treatment for any type of cancer within 1 year prior to study start;
15. Other medical, psychiatric, or behavioral factors that in the judgment of the principal Investigator may interfere with study participation or the ability to follow the intervention protocol;
16. Shift worker (a system of employment where an individual's normal hours of work are in part, outside the period of normal working day; 6am and 8pm);
17. Smoking, use of tobacco or a nicotine replacement product (within the last 3 months);
18. Allergies to barley or wheat flour;
19. Aversion or unwillingness to eat study foods;
20. Use of any prescription or non-prescription drug, herbal or nutritional supplement known to affect glycemia;
21. Participation in another clinical trial, current or in the past 4 weeks;
22. Unstable body weight (defined as \>5% change in 3 months) or actively participating in a weight loss program.