Impact of Blueberry Consumption on Gastrointestinal Health

The commensal bacteria that reside in the human gut, known as the gut microbiota, is a complex system that modulates local gut homeostasis and systemic biological processes. Several environmental factors have been shown to influence the gut milieu (including microbiota), and thus both gastrointestinal and host health. Relevant to the current proposal is the influence of body weight, diet, and circadian rhythms. In the current study, the investigators propose to use these common disruptors of gastrointestinal health through recruiting obese shift workers with a low-fiber diet to identify if these disrupted individuals can benefit from blueberry intake. Specifically, the study objectives are to determine if 24 g whole blueberry powder consumed daily can beneficially modify intestinal permeability, gut microbiota, microbial metabolites, and both gut-derived and systemic inflammation in those most susceptible to a pro-inflammatory milieu. This will be accomplished through a 14-week crossover study in which 28 individuals will be randomized by treatment group order to 4 weeks of whole blueberry powder and placebo powder, with a 4-week wash out in between the treatment periods.

Inclusion criteria

• obese (BMI +/- 30.0 kg/m2)
• shift workers (shift work overnight (third shift) +/= 3 days/week for the past 3 months)
• 19-70 years of age

Exclusion criteria

• patient history of gastrointestinal diseases except for hiatal hernia, GERD, or hemorrhoids, mild gastrointestinal symptoms
• elevated laboratory values from a comprehensive metabolic panel (CMP) and complete blood count (CBC) with the exception of glucose (+/= 126 mg/dL; if elevated, confirmed with HA1c of greater than or equal to 6.5%) and ALT, AST, or ALP over 2 times normal levels (to allow for mild elevations resulting from fatty liver often seen in obese) unless approved by study physician
• currently pregnant or plans to become pregnant during the study as determined by participant report
• antibiotic use within the last 12 weeks prior to enrollment
• presence of chronic metabolic disease (e.g., cardiovascular disease, diabetes, cancer) or per physician discretion
• recent (past 4 weeks) major change in dietary habits or a plan to have a major change in dietary habits during the study
• habitual blueberry consumption of more than 0.5 cups 2x/week or a 4-week washout period if consumes
• allergy or intolerance to blueberries
• consumption of supplemental fiber, probiotics or prebiotics without an appropriate 4-week washout period
• restrictive dietary patterns (e.g., ketogenic, Paleolithic) or a diet high in fiber (+/= 14 g/1000 kilocalories) to increase study result generalizability to the U.S. population (low-fiber diet), as well as provide another stimuli for gut leakiness
• unwillingness to consent to the study.