Effect of Strawberry Consumption on the Microbiome
Condition: Microbiome
Study type: Interventional

Summary: 
      This pilot study will assess the ability of daily consumption of two servings of California
      strawberries to alter gut microbiome composition, leading to increased bile secretion and
      decreased plasma cholesterol in a free-living population.
    

Detailed description: 
      This will be a randomized, double-blinded, placebo controlled, parallel design. Thirty
      subjects will be randomized to consume two servings of standardized freeze-dried strawberry
      powder (2 x 13g) daily or placebo for 4 weeks, followed by 2 weeks of follow up with beige
      diet only to observe whether the effect can be sustained for 2 weeks. Blood will be collected
      at baseline (week 0), weeks 4 and week 6 after strawberry consumption. On the day prior to
      the study visits participants will collect a stool and a 24-hr urine sample and bring to the
      lab. In addition, body weight and composition will be determined and questionnaires and 3-day
      food record will be completed. Twenty-four hour urine content of pelargonidin glucuronide
      will be measured for compliance. Plasma and fecal cholesterol and bile acids will be
      determined at baseline (week 0) and weeks 4 and 6.

      Subjects will be assigned an enrollment number after signing the informed consent form
      approved by the UCLA Medical Internal Review Board. Subjects will undergo a physical exam,
      complete medical history, and blood draw. A standard chem. panel will be performed at the
      UCLA clinical laboratory. Eligible subjects will be enrolled into the study upon completion
      of screening evaluations and will be randomized to the strawberry or placebo arm at their
      baseline visit.

      The study will be conducted in healthy free-living subjects (18-55 years). Subjects consume
      13 grams standard strawberry powder in the morning and afternoon/evening or placebo powder
      for 4 weeks. Subjects will be instructed to eat a beige diet (low fiber<10g and low
      polyphenols <3 servings of polyphenol rich fruit/vegetables per day) during the entire study
      period. 24 hr urine pelargonidin glucuronide will be measured at weeks 2 (baseline), 6 and 8
      for compliance. In addition, pelargondin, ellagic acid, dimethylellagic acid glucuronide and
      urolithin glucuronide will be measured in plasma and urine to determine strawberry
      phytochemical bioavailability and intestinal/microbiome metabolic capacity. Participants will
      meet with the dietitian for assessment of habitual dietary pattern and instructions on
      maintain on a beige diet. A list of foods with high fiber and phenolic compounds will be
      provided and subjects are instructed to follow the diet during the entirety of the study.

      A standardized freeze-dried strawberry powder and a strawberry placebo powder provided by the
      California Strawberry Commission will be used. Ten grams of freeze dried powder is equivalent
      to about 110 g fresh fruit. One serving of fresh strawberry (one cup) is estimated to weigh
      144 g and therefore is equivalent to 13 g of freeze dried powder. Subjects will consume two
      packages of 13 g of strawberry powder per day. The powder can be mixed into beverages and
      consumed with breakfast and dinner.

      Strawberry powder ingredients include Individually Quick Frozen (IQF) strawberries. Placebo
      powder ingredients include fructose, sucrose, dextrose, tapioca maltodextrin, modified food
      starch, erythritol, cellulose gum, citric acid (anhydrous), N-C Strawberry Flavor Natual
      WONF, xanthan gum, malic acid, sugar beet fiber, silicon dioxide, nat. strawberry-type
      flavor, FD&C Red #40, FD&C Yellow 6, FD&C Blue 2.
    

Intervention name(s): strawberry powder; placebo powder
Intervention type(s): Other; Other
Intervention description(s): Participants consume 2 packages of standard strawberry powder (13 g x 2) daily for 4 weeks; Participants consume 2 packages of placebo powder (13 g x 2) daily for 4 weeks
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Investigator)
Primary purpose: Other
Keywords: Strawberry; polyphenols; cholesterol