A study to investigate the effect of Yakult® containing L. casei Shirota on the intestinal microbiota, intestinal environment, and stool frequency in healthy adult and elderly subjects in Indonesia. The clinical phase of this study was conducted for 26 weeks in three different elderly houses. The subjects were grouped into two categories: probiotic and placebo group, according whether the subjects consumed product or placebo samples. Fecal sampling were taken three times during the study.

The study investigates the ingestion effect of a commercialized probiotic milk drink, Yakult®, for residents and staffs at Indonesian elderly houses (age limit: 18 - 95 years old). The study will be conducted as a double blind, placebo controlled parallel comparison study. There will be 26 weeks used for the study, comprised of: A 2-week baseline assessment period, and 24-week probiotic or placebo intake period.

From 112 subjects, the participants will be grouped into two: probiotic and placebo group. Those in probiotic group will consume Yakult® (Fermented milk drink containing over 6.5×10^9 CFUs of L. casei Shirota/65 ml), while placebo group will consume the placebo product (taste, appearance, component, and number of calories are the same as Yakult®, non-fermented milk product). The treatment intake will be done for 24 weeks (182 days).

During the study, the participants are expected to fill questionnaire of frequency of bowel movements and Chinese Constipation Questionnaire to obtain the defecation frequency (Bristol Stool score) and abdominal symptom scores. Fecal samples will be collected three times: on the last day of the baseline period (day 14±1), 12 weeks (day 98±1) after intake period, after the 24-weeks intake period (day 182±1). Afterwards, the obtained fecal samples will be further analyzed for its microbial composition, level of short-chain fatty acids and putrefactive compounds.

Inclusion Criteria:

• Understand and sign written informed consent
• Healthy adult and elderly subjects (adult: between 18 - 69 years old; elderly at least 70 years old.
• No history of an adverse reaction to any of the components of the active or placebo versions of the probiotic product.
• Can eat, regularly.
• Has been diagnosed by doctors as healthy both physically and mentally.
• Can abide by the experimental protocol.

Exclusion Criteria:

• Excessive alcohol consumption (defined as follows: male; over 28 glasses a week, female; over 21 glasses/week).
• Consume antibiotics or laxatives at least 2-week prior screening period.
• Consume ingestion of fermented dairy foods (yogurt), probiotic foods and/or prebiotic at least 2 weeks prior to the study.
• Reported current usage of Narcotics and Psychotropic,
• History of GI surgery i.e. Colectomy and Enterectomy.
• Symptoms meeting to Rome IV diagnostic criteria for irritable bowel syndrome
• Pregnant or childbearing women