Resistant maltodextrin (RMD) is an indigestible water soluble fiber that increases fecal bulk by enhancing growth of specific microbial populations; however the effect of RMD on bifidobacteria and total fecal weight is not clear. The purpose of this research study is to determine whether incorporating about ¼ cup of a fiber supplement into the diet will induce beneficial changes in gastrointestinal function, the fecal microbiota profile (increased number of healthy bacteria in stool) and immune processes resulting in improved quality of life.

This is a randomized, double-blind, placebo-controlled study. After obtaining informed consent, participants will be randomized to either consume 0, 15 or 25 grams of resistant maltodextrin (RMD) during the first arm of the study. During the first intervention period, participants will consume the RMD everyday for 3 weeks. After a 2-week post intervention period, participants will be crossed to one of the other treatments for 3 weeks, followed by a 2-week post intervention and then receive the final intervention for 3 weeks.

Participants will complete daily questionnaires and weekly gastrointestinal symptom questionnaires during the intervention and post-intervention periods. Stool samples will be collected at the baseline and final time points of each intervention. Dietary intake will also be assessed weekly during each intervention period.

Inclusion Criteria:

• Body mass index (BMI) of 18.5 to <30 kg/m2
• Usual fiber intake of <19 g/d for males and 13 g/d for females based on Food Frequency Questionnaire (FFQ) such as the NutritionQuest Fruit/Vegetable/Fiber Screener.
• Willing to complete daily and weekly questionnaires, 20 dietary recalls, and 15 stool collection days over approximately 18 weeks
• Willing to drink the study supplements for 3 weeks for each of the three intervention periods
• Willing to discontinue any prebiotic, fiber, or probiotic supplements or foods containing probiotics (e.g., yogurts with live, active cultures)
• Internet access for the duration of the protocol to complete online questionnaires
• On average you have 6 or more stools but fewer than 12

Exclusion Criteria:

• Does not meet above criteria

• Dietary fiber intake greater than half the adequate intake (AI) based on Automated Self-Administered Diet History (ASA24) (http://riskfactor.cancer.gov/tools/instruments/asa24/) dietary intake data collected during run-in period:

  • Females with a dietary fiber ≥13 g/d
  • Males with a dietary fiber ≥19 g/d

• Antibiotic use within 2 months from providing the screening stool sample

• Physician-diagnosed gastrointestinal disease or condition (such as ulcerative colitis, Crohn's disease, gastroparesis, cancer, peptic ulcer disease, Celiac disease, short bowel disease, ileostomy, colostomy) other than Gastroesophageal Reflux Disease (GERD), constipation, or diverticular disease

• Purposeful strenuous exercise of >300 minutes per week on average

• Women who are lactating or know they are pregnant