Evaluating Liking, Acceptability and Health Benefits of Grain Products
Condition: Food Preferences
Study type: Interventional

Summary: 
      The specific aims of the Grain Study are to determine if sensitivity to bitter taste affects
      the liking and acceptability of different grain products, to determine if exposure to
      different types of grain products, over a period of 6 weeks, changes liking and acceptability
      and to determine if the gut microbiota, bacterial fermentation products, or gastrointestinal
      function changes with consumption of whole grains or refined grains.
    

Detailed description: 
      Subjects will be recruited in accordance with inclusion and exclusion criteria listed below.
      During the screening process sensitivity to n-propyl-thiouracil (PROP) will be evaluated to
      classify subjects as "non-tasters", "tasters", and "supertasters".

      Subjects within each PROP class will be assigned to one of two different grain product
      'exposure' groups - Group 1 will receive predominantly Whole Grain (WG) products and Group 2
      will receive predominantly Refined Grain (RG) products (ratio of WG to RG assignment will be
      2:1). For a 6-week exposure period, subjects will receive weekly market baskets of grain
      products consisting of breakfast cereals, breads, snack items, and side dishes with the
      target of providing whole grains at a level of 50% of grain intake for the WG group (this is
      the current Dietary Guideline recommendation) and 15% for the RG group (this is the current
      estimated intake for U.S. adults). Before and after grain exposure, subjects will rate the
      acceptability and liking of numerous grain products. To accomplish this, subjects will
      participate in sensory evaluation tests using these products, and they will provide
      information using validated questionnaires and take implicit association tests. During the 6
      week study period, subjects will record use of the market basket grain products, and provide
      subjective scores for taste, convenience, nutrition, and general liking. The quality of the
      total dietary intake will be assessed using unannounced 24-h recalls. Biological samples will
      also be collected from subjects. Blood and urine samples will be collected to evaluate risk
      factors of chronic disease, and biomarkers of whole grain intake, fruits and vegetables.
      Saliva and fecal samples will be collected to measure changes in gut microbiota and to
      measure metabolites of bacterial fermentation. Breath hydrogen tests will be conducted to
      measure bacterial fermentation. Two weeks after the end of the intervention period, subjects
      will participate in a nominal group session to identify significant barriers and facilitators
      to inclusion of grain products into their diets. Follow-up visits at 26 and 52 weeks,
      post-intervention, will be scheduled with all subjects to re-evaluate acceptability, liking,
      and other variables related to whole grain intake.
    

Intervention name(s): Whole grain foods; Refined grains
Intervention type(s): Other; Other
Intervention description(s): Eight commonly consumed whole grain products that meet the consumers Dietary Guidelines recommendations for a period of six weeks.; Eight commonly consumed refined grain products given in amounts that fulfill the consumer's Dietary Guidelines for Americans recommendation over the course of six weeks.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: Acceptability; liking