The Effects of a High Protein Diet on Microbiota, Gastrointestinal Function and Wellness in Older Women

Older women will be randomized to a 18-week crossover study design. During each treatment period participants will be provided with a weight maintenance diet providing approximately 2 g/kg/day of protein.

Following a two-week baseline and in random order will have the following diets assigned:

The participants will be provided with a weight maintenance, high protein diet for two weeks, then for two-weeks will resume their normal diet;

The participants will come back into clinic and for the next two weeks to receive a high protein diet with a multi-strain probiotic for two weeks, then for two-weeks will resume their normal diet;

The participants will come back into clinic and for the next two weeks will receive a high protein diet with a prebiotic, then for two-weeks will resume their normal diet;

The participants will come back into clinic and for the next two weeks will receive a high protein diet with the synbiotic combination. then for two-weeks will resume their normal diet

Participants and researchers will be blinded for each treatment period (participants will receive a probiotic or placebo capsule, and a prebiotic or placebo sachet).

The following will be performed during the clinic visits: Questionnaires will assess quality of life (QoL), wellness, gastrointestinal symptoms, bowel movement frequency, and compliance. Hand-grip strength will be measured. Blood and urine samples will be collected at baseline and at weeks 2, 6,10 and 14. Stool samples will be collected at baseline and at weeks 2, 4, 6, 8,10, 12, 14 and 16.

Inclusion criteria

To participate in the study you must

• be a woman 65 years of age or older
• be willing to complete daily and weekly questionnaires
• be willing to wear a SenseWear Pro Armband (BodyMedia, Inc.) to monitor energy expenditure and establish dietary energy needs
• be willing to provide blood samples, stool samples, and urine samples throughout the course of the study
• be willing to discontinue prebiotics, probiotics and/or any fiber supplements for the duration of the study
• be willing to consume the provided diet for the designated 8 weeks of the study
• are willing to report and maintain their usual alcohol intake throughout the study
• are able to take foods, study fiber, probiotic, and placebo without the aid of another person
• able to attend all scheduled study appointments for the duration of the study
• have a usual protein intake consistent with United States' population as assessed by dietary analysis
• have a usual fiber intake consistent with United States' population as assessed by dietary analysis
• be willing to provide a social security number to receive study payment.

Exclusion criteria

To participate in the study you must NOT

• have a physician-diagnosed gastrointestinal disease or condition (such as ulcerative colitis, Crohn's disease, gastroparesis, peptic ulcer disease, cancer, celiac disease, short bowel disease, ileostomy)
• have had or are currently being treated for any known illnesses or conditions that may impact perceived health such as HIV/AIDS, immune modulating diseases (autoimmune, hepatitis, cancer, etc.), diabetes or chronic kidney disease
• be a vegetarian
• have any known food allergies or dietary restrictions
• be currently taking medication for constipation or diarrhea
• have taken antibiotics within the past 2 months
• be a current smoker
• be planning on loosing/gaining weight during the next 6 months
• typically consume no more than one alcoholic beverage per day
• have a BMI greater than 30