This Study Assessed the Impact of Diet on Gastric Emptying Time and Metabolic Flexibility

The purpose of this study is to understand how diet may affect carbohydrate digestion, gastric emptying time and overall health. The investigators will be recruiting 32 volunteers for this study. To be eligible for this study, you need to be between 18 and 50 years old, have a normal Body Mass Index, have a normal fasting blood glucose level, be free of any gastrointestinal diseases, diabetes, cardiovascular diseases, be free of wheat allergens, gluten intolerance or sensitivities, and allergy to millet, and not be pregnant or nursing. If you have any questions about the criteria, please ask the person consenting you.

In this study, participants will consume two test meals at different times to assess gastric emptying times. Test meals will consist of either corn starch (30 g) or pregelatinized (DE-1 Maltodextrin) starch in applesauce (200 g) with xanthan gum (0.2 g) to equalize viscosity. Ingredients will be mixed immediately before consumption. For assessment of gastric emptying time, we will use a non-invasive 13C-labeled octanoic acid breath test. In our proposed procedure, 13C octanoic acid will be added to test meals, and breath samples will be taken before and after ingestion up to 4 hours. Breath samples will be collected every 15 minutes for first 2 hours and every 30 minutes for the next 2 hours. Participants will breathe into 300 mL bags and their content will be evaluated for [13C] using a 13CO2 Urea Breath Analyzer POCone (Otsuka Electronics Co, Ltd, Osaka, Japan) as measures of gastric emptying. We have used the labeled substrate and breath collection methods in our lab under previously approved IRB protocols at Purdue University (IRB Protocols #1102010450, #1104010761, #1209012595, #1405014904, and #1502015807, #1611018484, #1706019377. In addition, before, during, and after each session, subjects will also be asked to fill out a short questionnaire with questions regarding your hunger and fullness at those times. Test meals will be prepared in the university with trained personnel. All the ingredients will be purchased from approved food manufacturers.

During testing days participants will be required to stay in the laboratory. Testing day sessions will last about 4 hours. The day prior testing, participants will be provided a standard meal but are not required to stay.

For assessment of diet composition, three 24-hour dietary recalls will be used. Participants will be called on three different days. During these sessions, participants will be asked to recount quantity and types of foods consumed throughout the day, including two weekdays and one weekend day, to form a comprehensive picture of their dietary habits. Dietary data will be collected and stored using no personally identifiable information.

The purpose of this study is to evaluate the continuous effect of slowly digestible carbohydrates consumption on gastric emptying and its potential health benefits.

Inclusion criteria

• BMI 18.5 - 25.0 kg/m2
• 18 - 50 years
• Normal fasting blood glucose

Exclusion criteria

• History of gastrointestinal disease
• Diabetes
• Pregnant and nursing women
• Wheat and/or gluten allergies or sensitivities
• Allergy to specific sources of slowly digestible carbohydrates