The purpose of this study is to determine whether healthy older adults, aged 65 to 80 years, consuming a probiotic each day for three weeks will have improved immune strength and digestive health. It is hypothesized that older adults consuming the probiotics will see a shift in their microbiota towards the "healthy" bacteria resulting in a greater proportion of immune cells, decreased inflammation, and better digestive health.

This is a randomized, double-blind, placebo controlled crossover design with two 3-week interventions and a 5-week washout period in between. Thirty-six participants will be enrolled. With informed consent, the daily questionnaire will be administered and a baseline stool sample will be obtained during the week before the start of each intervention period. Blood and saliva will be collected on the first and last day of each intervention period to assess immune function. A final stool sample will be obtained in the last week of the intervention period. Nutritional status, which can impact immune function, will be assessed using the Mini-Nutritional Assessment, Block Fiber Screen, and the Block 2005 Food Frequency Questionnaire. Daily questionnaires will record intake of the probiotic or placebo, level of stress, hours of sleep, visits to the physician, new medications, number of stools, etc. The Gastrointestinal Symptom Response Scale, which records gastrointestinal symptoms, such as bloating, gas, diarrhea, and constipation, over the past week will be completed at baseline and weekly during the interventions and the week following the interventions.

Inclusion Criteria:

• 65 to 80 years of age.
• willing and able to complete the Informed Consent Form in English
• willing to provide demographic information (age, race)
• willing and able to complete daily and weekly questionnaires regarding general wellness, bowel function and gastrointestinal symptoms.
• willing to provide 4 blood, 4 stool, and 4 saliva samples
• willing to discontinue any immune-enhancing dietary supplements ( e.g., prebiotics supplements, Echinacea, fish oil, vitamin E >200% of the RDA).
• able to take the study probiotic without the aid of another person.

Exclusion Criteria:

• not meet the above criteria.
• taking any medication for constipation or diarrhea.
• currently taking any anti-inflammatory drugs on a regular basis.
• current smoker.
• typically consume fermented foods or probiotics (e.g., yogurts with live, active cultures or supplements).
• currently being treated for or have any of the following physician- diagnosed diseases or conditions: HIV/AIDS, immune modulating diseases (autoimmune, hepatitis, cancer, etc.), kidney disease, diabetes or gastrointestinal disease or conditions (such as ulcerative colitis, Crohn's disease, gastroparesis, cancer, peptic ulcer disease, Celiac disease, short bowel disease, ileostomy, colostomy) other than GERD or diverticular disease or have a central venous catheter.
• received chemotherapy or other immune suppressing therapy within the last year.
• received antibiotic therapy in the past two months.
• cannot schedule planned immunizations to at least 4 weeks before the start of the study, in the week following the second blood draw, or after the 4th blood draw.