The Effect of a High Dietary Intake of Resistant Starch on Blood Glucose Levels in Women with Gestational Diabetes.

Resistant Starch (RS) Dietary Intervention Women who are randomised to either of the two dietary intervention groups (RS Diet or RS Supp). Both groups will receive dietary education on consuming a high RS diet from whole foods. All RS dietary education will be conducted face-to-face at Fiona Stanley Hospital by the Principal Investigator, who is a Dietitian with over 30 years experience. The education will be conducted during a single 30 minute individual session. A standardised teaching plan will be used and participants will be provided with written nutrition education material and sample menus specifically developed for this study. They will also receive a "Gut Feeling" cookbook which was written by researchers at Edith Cowan University and is available for purchase from www.ecu.edu.au/schools/medical-and-health-sciences/our-research/systems-and-intervention-research-centre-for-health/news-and-events/sirch/2017/07/gut-feeling-mindful-menus-for-the-microbiome The RS education tools and strategies have been piloted by this group in a non-pregnant population and achieved a median increase in dietary RS intake of greater than 6.6 g RS per day. The high RS diet will commence on Day 3 of the trial and continue until delivery of the baby. RS Supplement (RS Supp) In addition to a high RS diet, the RS Supp group will be instructed to begin to consume a powdered RS supplement of high-amylose maize type 2 resistant starch (HAMS-RS2). The supplement will be stirred into cold foods such as yoghurt, smoothies, mashed banana and hummus. Participants will introduce HAMS over a two-day adjustment period by consuming 20 g per day, half a sachet morning and night for two days. Then, increasing to a split dose of 2 x 20 g per day for the remainder of their pregnancy. The RS supplement contains 60 percent RS type 2. The final amount of RS in the 40 g of HAMS per day will be 24 g. Participants will have face-to-face or telephone contact with the Chief Investigator approximately every 2 weeks to assess adherence to the diet and supplement (if applicable), to remind them of the next steps in the study protocol and to answer questions. The last contact with the participants will be at 1-week post-partum. Adherence to the dietary and supplement interventions will be monitored via 3-day food diaries (Baseline to Day 3, Days 7-9 and three consecutive days in the 35th week of gestation), RS supplement consumption records, measurement of change in gut microbiota and increase in stool short chain fatty acid content.