Resistant Starch Wheat for Improved Metabolic Health
Condition: Gut Microbiota; Metabolism; Metabolic Health
Study type: Interventional

Summary: 
      The objective of this study is to determine the effect of wheat enriched in resistant starch
      (RS) on the generation of fermentation products by the lower gut microbes, the fecal
      microbiota profile, intestinal metabolites, and the glycemic response to a test meal compared
      to regular wheat.
    

Detailed description: 
      Resistant starch (RS) is a type of dietary fiber that provides fermentable carbohydrate (FC)
      in the lower bowel yielding positive effects on postprandial glycemia and weight management
      as well as digestive tract health. RS is defined as the portion of starch resistant to
      digestion by amylases, allowing it to reach the distal intestine where it can be fermented by
      the resident intestinal microbiota. A limited number of human studies using RS from high
      amylose corn have demonstrated that RS increases synthesis of gut peptides that improve
      glucose homeostasis and insulin secretion. Based on these studies, the FDA has recently
      approved the following health claims for resistant starch derived from corn (RS2): lowering
      of blood glucose, blood cholesterol, and blood pressure; increased mineral absorption;
      improved laxation; and reduced energy intake. The purpose in the proposed "proof of concept"
      study here is to show that RS provided in the form of wheat flour products has similar
      beneficial effects. The investigators aim to further explore the effect of RS on the gut
      microbiota. The intestinal microbiome is comprised of over one trillion bacterial cells
      comprised of approximately one thousand species that perform diverse functions ranging from
      energy harvest, angiogenesis, immunomodulation, and regulation of mood and behavior. Some of
      the major products of bacterial metabolism include acetate, propionate, and butyrate, the
      major short chain fatty acids (SCFA). These bioactive fermentation products have been
      associated with improved glucose homeostasis, attributed, in part, by their interactions with
      receptors on intestinal cells to augment secretion of glucagon-like peptide-1 (GLP-1), an
      incretin hormone known to stimulate insulin secretion.

      This study is a randomized, cross-over design consisting of two 1-week dietary intervention
      periods as well as a 2-week washout period in between. Subjects will be randomly assigned to
      receive either RS wheat first or regular wheat first, then will be crossed over to the
      opposite treatment following a 2-week washout period. Wheat products made from RS wheat and
      regular wheat will be provided and the volunteers will be instructed to incorporate the
      products into their usual diet for 7 days. This study will probe the associations between the
      gut microbiota profiles, fermentation of RS wheat, microbial-mediated alterations in bile
      acids, and glycemia. The investigators will measure these effects in healthy, middle-aged
      humans using an interdisciplinary approach that integrates nutrition, microbiology,
      intestinal physiology, and analytical chemistry.
    

Intervention name(s): Resistant Starch Wheat
Intervention type(s): Dietary Supplement
Intervention description(s): The investigators will be testing high amylose wheat varieties developed by Arcadia Biosciences that have high levels of RS in the endosperm, the source of refined flour. Compared to regular wheat varieties with RS levels of less than 1%, Arcadia's wheat varieties contain between 16% and 34% RS.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomized, cross-over design consisting of two 1-week dietary intervention periods as well as a 2-week washout period in between
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: Gut Microbiota; Glycemic Response; Resistant Starch; Fiber