Gastrointestinal Assessment of Three Novel RS4
Condition: Diet Modification
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Resistant Starch Type 4 Supplementation; Resistant Starch Type 4 Supplementation; Resistant Starch Type 4 Supplementation; Digestible Starch Supplementation
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Ten participants will supplement their normal dietary intake with RS4 daily for four consecutive weeks, with each week the amount of RS4 provided being increased (10 g, 20 g, 35 g and 50 g/day).; Ten participants will supplement their normal dietary intake with RS4 daily for four consecutive weeks, with each week the amount of RS4 provided being increased (10 g, 20 g, 35 g and 50 g/day).; Ten participants will supplement their normal dietary intake with RS4 daily for four consecutive weeks, with each week the amount of RS4 provided being increased (10 g, 20 g, 35 g and 50 g/day).; Ten participants will supplement their normal dietary intake with digestible starch daily for four consecutive weeks, with each week the amount of starch provided being increased.
Other intervention name(s): Modified potato starch; Modified corn starch; Modified tapioca starch; Corn starch
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Other
Keywords: Resistant Starch; Dietary Fiber; Gastrointestinal Microbiome; Gastrointestinal Tolerance