None listed
Conditions
Brief summary
Foods containing starches that undergo less small intestinal digestion have important implications for human health. By escaping digestion in the upper gut, starch that reaches the large bowel (resistant starch, RS) becomes a substrate for microbial fermentation and leads to higher production of short chain fatty acids (SCFA). These acids are not only integral to bowel health and protection against DNA damage, but also influence metabolism of peripheral tissues, including skeletal muscle, adipose tissue depots and liver, and contribute to the regulation and strengthening of immune system function and responses to infection. Additionally, slowing the rate and extent of amylolysis in the small bowel lowers the glycaemic response to food and improves blood glucose control, which can contribute to the prevention and management of type-2 diabetes. Western diets typically contain little RS because staple foods, such as cereals, are highly processed and contain starches that are readily digested in the upper gut. Consequently, RS intakes are commonly below half the suggested level of 20 g of RS per day for providing a range of health benefits. To help address this, we developed a wheat variety that contains high levels of amylose, a type of starch that has low digestibility compared to conventional wheat varieties. Although bread made from this wheat variety has a lower glycemic impact compared to conventional bread, its RS content has not been established. The purpose of this study is to establish the RS content of refined and wholemeal breads made from a novel high amylose wheat (HAW). To do this, we directly quantified the physiological RS content of breads made from a conventional (low amylose) wheat and the novel HAW in healthy ileostomates. It is hypothesised that the new HAW flour contains substantially more resistant starch than the control conventional wheat flour.
Interventions
The study will be divided into two test periods, each of which consist of 4 consecutive collection days (total of 8 d). The treatment sequence was randomised through the use of a Latin square randomization sequence that included 4 unique sequences: ABDC, BCAD, CDBA, and DACB. Testing will be carried out in the home or workplace of participants and there will be a total of four treatments.
The 4 treatment breads, low amylose wheat-refined, LAW-wholemeal, high amylose wheat-refined and HAW-wholem
The study will be divided into two test periods, each of which consist of 4 consecutive collection days (total of 8 d). The treatment sequence was randomised through the use of a Latin square randomization sequence that included 4 unique sequences: ABDC, BCAD, CDBA, and DACB. Testing will be carried out in the home or workplace of participants and there will be a total of four treatments. The 4 treatment breads, low amylose wheat-refined, LAW-wholemeal, high amylose wheat-refined and HAW-wholemeal (HAW-W), will be made from low amylose wheat or high amylose wheat flour according to a standard bread recipe (Belobrajdic et al, 2019, J Nutr, doi: 10.1093/jn/nxz067). The starch contents of the LAW and HAW breads were 24% and 74% amylose, respectively. The study will be run for four days (Monday to Thursday) over two consecutive weeks. During the two 4-d treatment periods and for 24 h before each test period, the participants will consume a diet consisting of foods commonly consumed in a Western diet (e.g. toast with jam, sandwich, yogurt, bollognase, meat and vegetable casserole), which contained low levels of starch. On the first day of each 4-d treatment period, participants will consume their assigned baseline foods only. For the subsequent three days, participants will be randomly assigned to consuming 65 g of 2 different test breads at breakfast on 2 different days or continuing with the baseline diet (no bread). Study participants will be provided with all the foods consumed during these two 4-d periods of dietary restriction. The test breads will be eaten by the participants in addition to the other foods consumed as part of the low-starch diet and a food diary was completed with any deviations recorded. Each day during the testing period the participants will be asked to collect ileostomy digesta from the ileostomy bag every 2 hours from 7am to 11pm and then again at 7am on the following day with the contents placed in portable freezers (20 °C). The ileostomy digesta samples will be obtained from the participant’s home by research staff and analysed in the laboratory for starch content. The stoma digesta samples from each volunteer collected during each 24 h period (7am until 7am the following day) were defrosted, pooled, homogenized, and subsampled for analysis. Throughout the study food checklists will be completed by study participants daily for assessment of compliance.
Sponsors
CSIRO Health and Biosecurity
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
20 Years to 80 Years
Healthy volunteers
No
Inclusion criteria
• Participants must have had minimal terminal ileum removed and have a conventional and well-functioning permanent ileostomy. • Age 20-80 years. • Willing to comply with alcohol and study diet restrictions.
Exclusion criteria
• History of alcohol or drug abuse. • Participation in a study within 30 days of commencement of the study. • Presence of gastrointestinal, renal, hepatic disease or intestinal inflammation. • Use of any medication that in the opinion of the investigator could interfere with the study or medications (eg antibiotics, codeine) likely to modulate small intestinal function. • Definite or suspected personal history or family history of adverse events or intolerance of starchy or other foods, which may be tested in this study. • Person considered by the investigator to be unwilling, unlikely or unable to comprehend or comply with the study protocol and restrictions. • Unwilling or unable to collect ileal effluent as required. • Persons taking any supplements containing carbohydrates (in particular resistant starch such as Hi-maize) which could interfere with study parameters.
Outcome results
None listed