Page Banner

United States Department of Agriculture

Agricultural Research Service

Related Topics

Fiber Study FL90
headline bar

Evaluating the health-promoting properties of a new fiber food


USDA, ARSWesternHumanNutritionResearchCenter invites overweight men and women, ages 20 - 60 years to participate in a 14-week research study to learn things about a fiber that will be used as a food ingredient.


Click here for more details


Evaluating the health-promoting properties of a new fiber food


USDA, ARSWesternHumanNutritionResearchCenter invites overweight men and women, ages 20 - 60 years to participate in a 14 week study with study visits on the UC Davis campus.


Who is conducting this study?

Nancy Keim, PhD, RD from the WesternHumanNutritionResearchCenter and Department of Nutrition is conducting this study. The study has been reviewed and approved by the UC Davis Committee for the Protection of Human Subjects.


What is the purpose of the study?

            In this study we hope to learn more about a dietary fiber in terms of how well it is digested, how many calories it contains, if it changes your bowel habits, and if it has the ability to improve your blood glucose levels and reduce inflammation.


Who can participate?

Healthy men and women, ages 20 - 60 years may be eligible to participate. Volunteers must be willing and able to come to the research center (WHNRC) on the UC Davis campus for scheduled visits during the 14 week study. Volunteers must have a Body Mass Index (the ratio of weight - to - height) between 25-35 kg/m2.


Who is NOT eligible to participate?


Adults who:

  • are outside of the age ranges described above
  • have a BMI of less than 25 kg/m2 or greater than 35 kg/m2
  • have had a diagnosis of type 1 or type 2 diabetes mellitus
  • have gastrointestinal diseases including malabsorption syndromes, chronic inflammatory bowel disease, colorectal cancer, celiac disease or documented gluten sensitivity, diverticulitis, Crohn's disease;
  • have anemia
  • regularly use prebiotics or probiotics, colonics and/or laxatives
  • have recently used (within 3 months) antibiotics, appetite suppressants
  • usually consume more than 15 grams per day of dietary fiber
  • regularly use tobacco/tobacco products
  • Women who are pregnant or lactating, or who have been in the past 6 months


What do I need to do to participate?


You will complete a telephone interview and in-person screening visit to determine your eligibility. During the study we will measure your height, weight and body composition (the amount of body fat and lean body mass). Three times during the study we will ask you to remember all the food and beverages you consumed during the previous 24-hours using a computer software program.

The study is 14 weeks long. It has baseline week, three 3-week "treatment" periods, and two 2-week "washout" periods. During the treatment periods, approximately weeks 2-4, 7-9, and 12-14, you will be given pre-portioned foods with the fiber added (juice, applesauce). You will eat one serving at breakfast and one serving at dinner each day. The fiber that is being tested in this study will be added at a low dose level for one treatment period, at a high dose level at another treatment period, and not added at all for another treatment period. The order of your treatments will be randomized, and neither you nor the investigators will know the order.


During the treatment periods, your diet will switch between your usual diet and a controlled diet that will be provided for you during weeks 3-4, 8-9, and 13-14. The controlled diet contains a variety of foods, including chicken, beef, dairy, soy, wheat and eggs. You will be asked to eat all of the food provided. You may drink up to 2 cups/day of black coffee or tea, and drink water as needed. The controlled diet will contain the pre-portioned foods with fiber added. During the weeks that you are on the controlled diet, you will come to the WHNRC to eat breakfast weekdays (Monday-Friday), and the remaining meals for the day will be packed for you to take out. All study foods and beverages for weekend days will be packed for you to take out and eat at home.


You will be asked to collect all the urine that you pass for seven consecutive days during study weeks 4, 9, and 14. You will also be asked to collect all stools passed for seven consecutive days during study weeks 4, 9, and 14. We will provide supplies and instructions for both. We will measure the amount of time it takes for the food you eat to move through your digestive tract using a "marker". We will ask you to collect a single stool sample during weeks 1, 6, and 11, and to keep log books related to urine and stool collections during the study.


Three times during the study, at or near the end of weeks 4, 9 and 11, you will be asked to come to WHNRC for a day-long (about 9 hour) test day protocol. You will arrive in the morning, not having eaten any foods or beverages for the past 12 hours. After we weigh you and measure your body composition, a registered nurse will place a catheter in a vein in your arm that will be used to sample your blood during the day. In addition to getting blood samples, we will also collect breath samples and have you record your appetite sensations and other health questionnaires. You will eat a standard breakfast meal, and about four hours later, you will eat a standard lunch meal. On this test day, you will continue to collect your complete urine and stool samples.


Are there benefits to you from this study?

            Consuming dietary fiber may improve gastrointestinal health and may also improve glucose tolerance. However, there is no guarantee that consuming this dietary fiber will benefit participants directly. A study of this nature will help researchers better understand the links between dietary ingredients and intestinal health.


Will I be compensated?

            Each person will receive a total of $1,000 in monetary compensation for completing the full study. Compensation will be divided up depending on how much you complete: $10 for each of three single stool collections; $10 for each of three 24-h diet recalls; $75 for test day 1; $125 for urine and stool collections during Treatment period 1; $125 for completing test day 2; $175 for urine and stool collections during Treatment period 2; $150 for test day 3; $250 for urine and stool collections during Treatment period 3; and $40 for completing all GI and urine logs and food checklists.


What should I do if I have questions?

Call (530) 752-5177 and press #5

Last Modified: 8/13/2016
Footer Content Back to Top of Page