Gastrointestinal Assessment of Three Novel RS4
Gastrointestinal Assessment of Three Novel RS4
The rates of chronic diseases like obesity, diabetes, and heart disease are rising across the
 world. This is especially true in industrialized countries like Canada and the USA. Even
 though there are many possible causes for these increases. One prominent cause is our refined
 diet, which greatly lacks dietary fiber. This 'fiber gap' between the amount of fiber
 actually eaten and the amount that should be eaten is likely promoting these diseases.

 It is known that a high fiber diet can benefit health and the health of the gut bacteria. It
 is also know that these gut microbes can help cause and prevent diseases. When fiber is
 eaten, it gets broken down not by us, but by our gut microbes. During this process
 by-products called short-chain fatty acids (SCFA) are made. These SCFA have been shown to
 promote health. Therefore, it is thought that fiber changes the gut microbes to produce more
 SCFA, which may improve overall health.

 In order to aid our microbes and improve our health we need to find ways to reduce this
 'fiber gap'. One possibility is to add fiber to our refined diet. To do so we must first
 learn how different fibers perform in our gut. This includes how our gut tolerates increasing
 amounts of fiber, and how our microbes respond. The purpose of this study is to learn how
 different types of resistant starch perform in our gut, including gastrointestinal tolerance.
 By doing so we will determine the ideal dose and type of these fibers to use in future
 studies.
The investigators propose a 4 week gastrointestinal (GI) assessment study to determine both
 the ideal dose and type of resistant starch to use in future studies. The following specific
 aims are offered:

 AIM 1: GI Tolerance. Preform a randomized, placebo-controlled, double-blind,
 parallel-four-arm human intervention study to assess the GI tolerance of 3 novel resistant
 starch type IV (RS4) at dose up to 50 g per day.

 Interested participants will be asked to attend a screening visit at Human Nutrition Research
 Unit, where lifestyle and anthropometric information will be collected to determine
 eligibility. Eligible participants (N = 40) will be stratified based on gender and randomly
 assigned to 1 of 4 groups, where they will be asked to supplement their diet for 4 weeks with
 either a RS4 (experimental arms) or a digestible starch (control arm). The weight of total
 starch (digestible plus RS) provided in each experimental arm will be dependent on the purity
 of the individual RS4 products. Subjects will supplement their diet with 10 g, 20 g, 35 g and
 50 g of total dietary fiber (as RS) daily over the course of weeks 1, 2, 3 and 4,
 respectively. The amount of digestible starch provided in the control arm will be equal to
 the mean amount of total starch provided across the 3 experimental arms. All starch products
 will be provided in powder form.

 Methodologies previously described by Maki et al. will be employed to evaluate the overall GI
 tolerance of the RS4 products by assessing changes in GI symptom, bowel movement frequency,
 and bowel movement consistency, and by comparing these changes to those changes observed in
 the control arm (digestible starch - Maki et al., Int J Food Sci Nutr, 2013). Participants
 will keep a daily study journal, which included a bowel habits questionnaire, over the course
 of the 4 week study, and they will also complete weekly GI tolerance and satiety
 questionnaires during their weekly study visits. Participants will also be asked to complete
 two 24-h recalls, both prior to starting the dietary intervention and during week 4. All 24-h
 recalls will be completed online through the Canadian Automated Self-Administered 24h (ASA24)
 recall system.

 AIM 2: Evaluate prebiotic and dose dependent effect on the microbiome. Evaluate the effect of
 the 3 distinct RS4 types on gut microbiota composition and structure in a dose dependent
 manner.

 Fecal samples will be collected at baseline and at the end of each intervention week (weeks
 1-4). Fecal samples will be used to both characterize the fecal microbial community via 16S
 ribosomal RNA next-generation sequencing, and to quantify fecal short-chain fatty acid
 concentrations via gas chromatography. Short-term characterization of the fecal microbiome
 will provide a systematic assessment of the individualized response between 3 structurally
 distinct types of RS4, while further allowing an intricate assessment of the prebiotic dose
 effect upon significantly increasing the dose of RS towards 50 g per day. This analysis will
 provide critical information on how distinct types of RS4 shape the gut microbiome in humans,
 and which dose is necessary to achieve such effects.
Inclusion Criteria:

 -  men and pre-menopausal, non-pregnant or non-lactating women

 -  non-vegetarian

 -  non-smoking

 -  alcohol intake ≤8 drinks/week

 -  ≤5 h/week of moderate-vigorous exercise

 Exclusion Criteria:

 -  acute or chronic GI illnesses, conditions, or issues

 -  history of GI surgical intervention

 -  chronic or current use of anti-hypertensive, lipid-lowering, anti-diabetic, analgesic,
 or laxative medications

 -  antibiotic treatment in the last 3 months

 -  use of fiber or probiotics supplements

 -  allergies or intolerances to fiber sources